MXenes are emerging rapidly as promising electrode materials for energy storage due to their high electronic conductivity and rich surface chemistry, but their potassium storage performance is unsatisfactory because of the large size of K⁺ and irreversible interfacial reaction. Here, a developed 3D foam-like MXene scaffold (3D-FMS) is constructed via an electrostatic neutralization of Ti₃C₂T_x with positive-charged melamine followed with calcination, which offers massive surface-active sites and facilitates fast K⁺ transfer for boosting the potassium-ion storage capacity and dynamics. In addition, using KFSI-based electrolyte, the formation of a robust solid electrolyte interface layer with more inorganic components on MXene anode is revealed for enhancing the Coulombic efficiency. Consequently, the 3D-FMS with KFSI-based electrolyte delivers enhanced potassium-ion storage performance in terms of capacity (161.4 mAh g^-1 at 30 mA g^-1), rate capability (70 mAh g^-1 at 2 A g^-1), and cycling stability (80.5 mAh g^-1 at 1 A g^-1 after 2000 cycles). Moreover, the assembled 3D-FMS//activated carbon potassium-ion hybrid supercapacitor delivers a high energy density of 57 Wh kg^-1 at a power density of 290 W kg^-1. These excellent performances demonstrate the great superiority of 3D-FMS in KFSI-based electrolyte and may accelerate the development of MXene-based materials for potassium storage systems.

Supercapacitors based on two-dimensional MXene (Ti₃C₂T_z) have shown extraordinary performance in ultrathin electrodes with low mass loading, but usually there is a significant reduction in high-rate performance as the thickness increases, caused by increasing ion diffusion limitation. Further limitations include restacking of the nanosheets, which makes it challenging to realize the full potential of these electrode materials. Herein, we demonstrate the design of a vertically aligned MXene hydrogel composite, achieved by thermal-assisted self-assembled gelation, for high-rate energy storage. The highly interconnected MXene network in the hydrogel architecture provides very good electron transport properties, and its vertical ion channel structure facilitates rapid ion transport. The resulting hydrogel electrode show excellent performance in both aqueous and organic electrolytes with respect to high capacitance, stability, and high-rate capability for up to 300 µm thick electrodes, which represents a significant step toward practical applications.

Triboelectric nanogenerators (TENGs) have emerged as promising candidates for integrating with flexible electronics as self-powered systems owing to their intrinsic flexibility, biocompatibility, and miniaturization. In this study, an improved flexible TENG with a tile-nanostructured MXene/polymethyl methacrylate (PMMA) composite electrode (MP-TENG) is proposed for use in wireless human health monitor. The multifunctional tile-nanostructured MXene/PMMA film, which is self-assembled through vacuum filtration, exhibits good conductivity, excellent charge capacity, and high flexibility. Thus, the MXene/PMMA composite electrode can simultaneously function as a charge-generating, charge-trapping, and charge-collecting layer. Furthermore, the charge-trapping capacity of a tile nanostructure can be optimized on the basis of the PMMA concentration. At a mass fraction of 4% PMMA, the MP-TENG achieves the optimal output performance, with an output voltage of 37.8 V, an output current of 1.8 µA, and transferred charge of 14.1 nC. The output power is enhanced over twofold compared with the pure MXene-based TENG. Moreover, the MP-TENG has sufficient power capacity and durability to power small electronic devices. Finally, a wireless human motion monitor based on the MP-TENG is utilized to detect physiological signals in various kinematic motions. Consequently, the proposed performance-enhanced MP-TENG proves a considerable potential for use in health monitoring, telemedicine, and self-powered systems.

Modulation of Si–O bonds under mild conditions has been a challenging issue in the field of material science, which is critical to manufacture high-performance silica-based optical and photonic devices. Herein, we introduce a nondestructive technique to achieve Si–O bond rearrangement, leading to plastic deformation and photoluminescence enhancement of amorphous silica nanoparticles using supercritical carbon dioxides in EtOH/H₂O solution under mild temperature. Specifically, plastic deformation is achieved by treating hollow mesoporous silica nanospheres using supercritical CO₂ at 40°C under 20 MPa. Experimental and theoretical studies revealed the critical role of supercritical CO₂ in the plastic deformation process, which can be intercalated into the hollow mesoporous silica nanospheres with anisotropic stresses and induces the rearrangement of Si–O bonds and transformation of ring structures. This work suggests a novel approach to engineer high-performance nano-silica glass components for numerous optical and photonic devices under mild condition.

Ever-increasing emissions of anthropogenic carbon dioxide (CO₂) cause global environmental and climate challenges. Inspired by biological photosynthesis, developing effective strategies NeuNlto up-cycle CO₂ into high-value organics is crucial. Electrochemical CO₂ reduction reaction (CO₂RR) is highly promising to convert CO₂ into economically viable carbon-based chemicals or fuels under mild process conditions. Herein, mesoporous indium supported on multi-walled carbon nanotubes (mp-In@MWCNTs) is synthesized via a facile wet chemical method. The mp-In@MWCNTs electrocatalysts exhibit high CO₂RR performance in reducing CO₂ into formate. An outstanding activity (current density -78.5 mA cm^-2), high conversion efficiency (Faradaic efficiency of formate over 90%), and persistent stability (∼30 h) for selective CO₂-to-formate conversion are observed. The outstanding CO₂RR process performance is attributed to the unique structures with mesoporous surfaces and a conductive network, which promote the adsorption and desorption of reactants and intermediates while improving electron transfer. These findings provide guiding principles for synthesizing conductive metal-based electrocatalysts for high-performance CO₂ conversion.

Printed micro-supercapacitors (MSCs) have shown broad prospect in flexible and wearable electronics. Most of previous studies focused on printing the electrochemically active materials paying less attention to other key components like current collectors and electrolytes. This study presents an all-printing strategy to fabricate in-plane flexible and substrate-free MSCs with hierarchical encapsulation. This new type of “all-in-one” MSC is constructed by encapsulating the in-plane interdigital current collectors and electrodes within the polyvinyl-alcohol-based hydrogel electrolyte via sequential printing. The bottom electrolyte layer of this fully printed MSCs helps protect the device from the limitation of conventional substrate, showing excellent flexibility. The MSCs maintain a high capacitance retention of 96.84% even in a completely folded state. An optimal electrochemical performance can be achieved by providing ample and shorter transport paths for ions. The MSCs using commercial activated carbon as the active material are endowed with a high specific areal capacitance of 1892.90 mF cm^-2 at a current density of 0.3 mA cm^-2, and an outstanding volumetric energy density of 9.20 mWh cm^-3 at a volumetric power density of 6.89 mW cm^-3. For demonstration, a thermo-hygrometer is stably powered by five MSCs which are connected in series and wrapped onto a glass rod. This low-cost and versatile all-printing strategy is believed to diversify the application fields of MSCs with high capacitance and excellent flexibility.

Energy density, the Achilles’ heel of aqueous supercapacitors, is simultaneously determined by the voltage window and specific capacitance of the carbon materials, but the strategy of synchronously boosting them has rarely been reported. Herein, we demonstrate that the rational utilization of the interaction between redox mediators (RMs) and carbon electrode materials, especially those with rich intrinsic defects, contributes to extended potential windows and more stored charges concurrently. Using 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl (4OH-TEMPO) and intrinsic defect-rich carbons as the RMs and electrode materials, respectively, the potential window and capacitance are increased by 67% and sixfold in a neutral electrolyte. Moreover, this strategy could also be applied to alkaline and acid electrolytes. The first-principle calculation and experimental results demonstrate that the strong interaction between 4OH-TEMPO and defect-rich carbons plays a key role as preferential adsorbed RMs may largely prohibit the contact of free water molecules with the electrode materials to terminate the water splitting at elevated potentials. For the RMs offering weaker interaction with the electrode materials, the water splitting still proceeds with a thus sole increase of the stored charges. The results discovered in this work could provide an alternative solution to address the low energy density of aqueous supercapacitors.

Inhomogeneous lithium-ion (Li⁺) deposition is one of the most crucial problems, which severely deteriorates the performance of solid-state lithium metal batteries (LMBs). Herein, we discovered that covalent organic framework (COF-1) with periodically arranged boron-oxygen dipole lithiophilic sites could directionally guide Li⁺ even deposition in asymmetric solid polymer electrolytes. This in situ prepared 3D cross-linked network Poly(ACMO-MBA) hybrid electrolyte simultaneously delivers outstanding ionic conductivity (1.02 × 10^-3 S cm^-1 at 30°C) and excellent mechanical property (3.5 MPa). The defined nanosized channel in COF-1 selectively conducts Li⁺ increasing Li⁺ transference number to 0.67. Besides, The COF-1 layer and Poly(ACMO-MBA) also participate in forming a boron-rich and nitrogen-rich solid electrolyte interface to further improve the interfacial stability. The Li‖Li symmetric cell exhibits remarkable cyclic stability over 1000 h. The Li‖NCM523 full cell also delivers an outstanding lifespan over 400 cycles. Moreover, the Li‖LiFePO₄ full cell stably cycles with a capacity retention of 85% after 500 cycles. the Li‖LiFePO₄ pouch full exhibits excellent safety performance under pierced and cut conditions. This work thereby further broadens and complements the application of COF materials in polymer electrolyte for dendrite-free and high-energy-density solid-state LMBs.

For protonic ceramic fuel cells, it is key to develop material with high intrinsic activity for oxygen activation and bulk proton conductivity enabling water formation at entire electrode surface. However, a higher water content which benefitting for the increasing proton conductivity will not only dilute the oxygen in the gas, but also suppress the O₂ adsorption on the electrode surface. Herein, a new electrode design concept is proposed, that may overcome this dilemma. By introducing a second phase with high-hydrating capability into a conventional cobalt-free perovskite to form a unique nanocomposite electrode, high proton conductivity/concentration can be reached at low water content in atmosphere. In addition, the hydronation creates additional fast proton transport channel along the two-phase interface. As a result, high protonic conductivity is reached, leading to a new breakthrough in performance for proton ceramic fuel cells and electrolysis cells devices among available air electrodes.

Bi₂Te₃-based materials have drawn much attention from the thermoelectric community due to their excellent thermoelectric performance near room temperature. However, the stability of existing n-type Bi₂(Te,Se)₃ materials is still low due to the evaporation energy of Se (37.70 kJ mol^-1) being much lower than that of Te (52.55 kJ mol^-1). The evaporated Se from the material causes problems in interconnects of the module while degrading the efficiency. Here, we have developed a new approach for the high-performance and stable n-type Se-free Bi₂Te₃-based materials by maximizing the electronic transport while suppressing the phonon transport, at the same time. Spontaneously generated FeTe₂ nanoinclusions within the matrix during the melt-spinning and subsequent spark plasma sintering is the key to simultaneous engineering of the power factor and lattice thermal conductivity. The nanoinclusions change the fermi level of the matrix while intensifying the phonon scattering via nanoparticles. With a fine-tuning of the fermi level with Cu doping in the n-type Bi₂Te₃–0.02FeTe₂, a high power factor of ∼41 × 10^-4 Wm^-1 K^-2 with an average zT of 1.01 at the temperature range 300–470 K are achieved, which are comparable to those obtained in n-type Bi2(Te,Se)₃ materials. The proposed approach enables the fabrication of high-performance n-type Bi₂Te₃-based materials without having to include volatile Se element, which guarantees the stability of the material. Consequently, widespread application of thermoelectric devices utilizing the n-type Bi₂Te₃-based materials will become possible.

Semitransparent organic solar cells show attractive potential in the application of building-integrated photovoltaics, agrivoltaics, floating photovoltaics, and wearable electronics, as their multiple functionalities of electric power generation, photopermeability, and color tunability. Design and exploration of semitransparent organic solar cells with optimal and balanced efficiency and average visible light transmittance and simultaneously high stability are in great demand. In this work, based on a layer-by-layer-processed active layer and an ultrathin metal electrode, inverted semitransparent organic solar cells (ITO/AZO/PM6/BTP-eC9/MoO₃/Au/Ag) were fabricated. Optimal and balanced efficiency and average visible light transmittance were demonstrated, and simultaneously promising thermal and light stability were achieved for the obtained devices. The power conversion efficiency of 13.78–12.29% and corresponding average visible light transmittance of 14.58–25.80% were recorded for the ST-OSC devices with 25–15 nm thick Ag electrodes, respectively. Superior thermal and light stability with ∼90% and ∼85% of initial efficiency retained in 400 h under 85°C thermal stress and AM1.5 solar illumination were demonstrated, respectively.

Nickel oxide (NiO_X) has been established as a highly efficient and stable hole-transporting layer (HTL) in perovskite solar cells (PSCs). However, existing deposition methods for NiO_X have been restricted by high-vacuum processes and fail to address the energy level mismatch at the NiO_X/perovskite interface, which has impeded the development of PSCs. Accordingly, we explored the application of NiO_X as a hybrid HTL through a sol–gel process, where a NiO_X film was pre-doped with Ag ions, forming a p/p⁺ homojunction in the NiO_X-based inverted PSCs. This innovative approach offers two synergistic advantages, including the enlargement of the built-in electric field for facilitating charge separation, optimizing energy level alignment, and charge transfer efficiency at the interface between the perovskite and HTL. Incorporating this hybrid HTL featuring the p/p⁺ homojunction in the inverted PSCs resulted in a high-power conversion efficiency (PCE) of up to 19.25%, significantly narrowing the efficiency gap compared to traditional n-i-p devices. Furthermore, this innovative strategy for the HTL enhanced the environmental stability to 30 days, maintaining 90% of the initial efficiency.

Solar steam generation is a promising water purification technology due to its low-cost and environmentally friendly applications in water purification and desalination. However, hydrophilic or hydrophobic materials alone are insufficient in achieving necessary characteristics for constructing high-quality solar steam generators with good comprehensive properties. Herein, novel hydrophile/hydrophobe amphipathic Janus nanofibers aerogel is designed and used as a host material for preparing solar steam generators. The product consists of an internal cubic aerogel and an external layer of photothermal materials. The internal aerogel is composed of electrospun amphipathic Janus nanofibers. Owing to the unique composition and structure, the prepared solar steam generator integrates the features of high water evaporation rate (2.944 kg m^-2 h^-1 under 1 kW m^-2 irradiation), self-floating, salt-resisting, and fast performance recovery after flipping. Moreover, the product also exhibits excellent properties on desalination and removal of organic pollutants. Compared with traditional hydrophilic aerogel host material, the amphipathic Janus nanofibers aerogel brings much higher water evaporation rate and salt resistance.

Metal exsolution engineering has been regarded as a promising strategy for activating intrinsically inert perovskite oxide catalysts toward efficient oxygen evolution reaction. Traditional metal exsolution processes on perovskites are often achieved by using the reducing hydrogen gas; however, this is not effective for the relatively stable phase, such as Ruddlesden–Popper perovskite oxides. To address this issue, triphenylphosphine is proposed to be a reduction promotor for accelerating the reduction and migration of the target metal atoms, aiming to achieve the effective exsolution of metallic species from Ruddlesden–Popper-type parent perovskites. Upon oxygen evolution reaction, these exsolved metallic aggregates are reconstructed into oxyhydroxides as the real active centers. After further modification by low-percentage iridium oxide nanoclusters, the optimal catalyst delivered an overpotential as low as 305 mV for generating the density of 10 mA cm^-2, outperforming these reported noble metal-containing perovskite-based alkaline oxygen evolution reaction electrocatalysts. This work provides a potential approach to activate catalytically inert oxides through promoting surface metal exsolution and explores a novel class of Ruddlesden–Popper-type oxides for electrocatalytic applications.

All-solid-state lithium metal batteries (ASSLMBs) with solid electrolytes (SEs) have emerged as a promising alternative to liquid electrolyte-based Li-ion batteries due to their higher energy density and safety. However, since ASSLMBs lack the wetting properties of liquid electrolytes, they require stacking pressure to prevent contact loss between electrodes and SEs. Though previous studies showed that stacking pressure could impact certain performance aspects, a comprehensive investigation into the effects of stacking pressure has not been conducted. To address this gap, we utilized the Li₆PS₅Cl solid electrolyte as a reference and investigated the effects of stacking pressures on the performance of SEs and ASSLMBs. We also developed models to explain the underlying origin of these effects and predict battery performance, such as ionic conductivity and critical current density. Our results demonstrated that an appropriate stacking pressure is necessary to achieve optimal performance, and each step of applying pressure requires a specific pressure value. These findings can help explain discrepancies in the literature and provide guidance to establish standardized testing conditions and reporting benchmarks for ASSLMBs. Overall, this study contributes to the understanding of the impact of stacking pressure on the performance of ASSLMBs and highlights the importance of careful pressure optimization for optimal battery performance.

Due to a high energy density, layered transition-metal oxides have gained much attention as the promising sodium-ion batteries cathodes. However, they readily suffer from multiple phase transitions during the Na extraction process, resulting in large lattice strains which are the origin of cycled-structure degradations. Here, we demonstrate that the Na-storage lattice strains of layered oxides can be reduced by pushing charge transfer on anions (O^2-). Specifically, the designed O3-type Ru-based model compound, which shows an increased charge transfer on anions, displays retarded O3–P3–O1 multiple phase transitions and obviously reduced lattice strains upon cycling as directly revealed by a combination of ex situ X-ray absorption spectroscopy, in situ X-ray diffraction and geometric phase analysis. Meanwhile, the stable Na-storage lattice structure leads to a superior cycling stability with an excellent capacity retention of 84% and ultralow voltage decay of 0.2 mV/cycle after 300 cycles. More broadly, our work highlights an intrinsically structure-regulation strategy to enable a stable cycling structure of layered oxides meanwhile increasing the materials’ redox activity and Na-diffusion kinetics.

Exploring a novel strategy for large-scale production of battery-type Ni(OH)₂-based composites, with excellent capacitive performance, is still greatly challenging. Herein, we developed a facile and cost-effective strategy to in situ grow a layer of Ni(OH)₂/Ti₃C₂T_x composite on the nickel foam (NF) collector, where Ti₃C₂T_x is not only a conductive component, but also a catalyst that accelerates the oxidation of NF to Ni(OH)₂. Detailed analysis reveals that the crystallinity, morphology, and electronic structure of the integrated electrode can be tuned via the electrochemical activation, which is beneficial for improving electrical conductivity and redox activity. As expected, the integrated electrode shows a specific capacity of 1.09 C cm^-2 at 1 mA cm^-2 after three custom activation cycles and maintains 92.4% of the initial capacity after 1500 cycles. Moreover, a hybrid supercapacitor composed of Ni(OH)₂/Ti₃C₂T_x/NF cathode and activated carbon anode provides an energy density of 0.1 mWh cm^-2 at a power density of 0.97 mW cm^-2, and excellent cycling stability with about 110% capacity retention rate after 5000 cycles. This work would afford an economical and convenient method to steer commercial Ni foam into advanced Ni(OH)₂-based composite materials as binder-free electrodes for hybrid supercapacitors.

Silicon oxide (SiO_x, 0 < x ≤ 2) has been recognized as a prominent anode material in lithium-ion batteries and sodium-ion batteries due to its high theoretical capacity, suitable electrochemical potential, and earth abundance. However, it is intrinsically poor electronic conductivity and excessive volume expansion during potassiation/depotassiation process hinder its application in potassium-ion batteries. Herein, we reported a hierarchical porous C/SiO_x potassium-ion batteries anode using lignite as raw material via a one-step carbonization and activation method. The amorphous C skeleton around SiO_x particles can effectively buffer the volume expansion, and improve the ionic/electronic conductivity and structural integrity, achieving outstanding rate capability and cyclability. As expected, the obtained C/SiO_x composite delivers a superb specific capacity of 370 mAh g^-1 at 0.1 A g^-1 after 100 cycles as well as a highly reversible capacity of 208 mAh g^-1 after 1200 cycles at 1.0 A g^-1. Moreover, the potassium ion storage mechanism of C/SiO_x electrodes was investigated by ex-situ X-ray diffraction and transmission electron microscopy, revealing the formation of reversible products of K_6.8Si_45.3 and K₄SiO₄, accompanied by generation of irreversible K₂O after the first cycle. This work sheds light on designing low-cost Si-based anode materials for high-performance potassium-ion batteries and beyond.

In this study, wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride (PVDF) films incorporated with cobalt-based metal–organic framework (Co-MOF) were developed. The enhanced output performance of the TENGs was attributed to the phase transition of PVDF from α-crystals to β-crystals, as facilitated by the incorporation of the MOF. The synthesis conditions, including metal ion, concentration, and particle size of the MOF, were optimized to increase open-circuit voltage (V_OC) and open-circuit current (I_SC) of PVDF-based TENGs. In addition to high operational stability, mechanical robustness, and long-term reliability, the developed TENG consisting of PVDF incorporated with Co-MOF (Co-MOF@PVDF) achieved a V_OC of 194 V and an I_SC of 18.8 µA. Furthermore, the feasibility of self-powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system (GPS) device. The local position of the user in real-time through GPS was displayed on a mobile interface, powered by the battery charged through friction-induced electricity generation.

To unlock the full potential of PSCs, machine learning (ML) was implemented in this research to predict the optimal combination of mesoporous-titanium dioxide (mp-TiO₂) and weight percentage (wt%) of phenyl-C₆₁-butyric acid methyl ester (PCBM), along with the current density (J_sc), open-circuit voltage (V_oc), fill factor (ff), and energy conversion efficiency (ECE). Then, the combination that yielded the highest predicted ECE was selected as a reference to fabricate PCBM-PSCs with nanopatterned TiO₂ layer. Subsequently, the PCBM-PSCs with nanopatterned TiO₂ layers were fabricated and characterized to further understand the effects of nanopatterning depth and wt% of PCBM on PSCs. Experimentally, the highest ECE of 17.338% is achieved at 127 nm nanopatterning depth and 0.10 wt% of PCBM, where the J_sc, V_oc, and ff are 22.877 mA cm^-2, 0.963 V, and 0.787, respectively. The measured J_sc, V_oc, ff, and ECE values show consistencies with the ML prediction. Hence, these findings not only revealed the potential of ML to be used as a preliminary investigation to navigate the research of PSCs but also highlighted that nanopatterning depth has a significant impact on J_sc, and the incorporation of PCBM on perovskite layer influenced the V_oc and ff, which further boosted the performance of PSCs.

Manufacturing thin-film components is crucial for achieving high-efficiency and high-power thermal batteries (TBs). However, developing binders with low-gas production at the operating temperature range of TBs (400–550°C) has proven to be a significant challenge. Here, we report the use of acrylic acid derivative terpolymer (LA136D) as a low-volatile binder for thin-film cathode fabrication and studied the chain scission and chemical bond-breaking mechanisms in pyrolysis. It is shown LA136D defers to random-chain scission and cross-linking chain scission mechanisms, which gifts it with a low proportion of volatile products (ψ, ψ = 39.2 wt%) at even up to 550°C, well below those of the conventional PVDF (77.6 wt%) and SBR (99.2 wt%) binders. Surprisingly, LA136D contributes to constructing a thermal shock-resistant cathode due to the step-by-step bond-breaking process. This is beneficial for the overall performance of TBs. In discharging test, the thin-film cathodes exhibited a remarkable 440% reduction in polarization and 300% enhancement in the utilization efficiency of cathode materials, while with just a slight increase of 0.05 MPa in gas pressure compared with traditional “thick-film” cathode. Our work highlights the potential of LA136D as a low-volatile binder for thin-film cathodes and shows the feasibility of manufacturing high-efficiency and high-power TBs through polymer molecule engineering.

Cubic silicon carbide (3C-SiC) has superior mobility and thermal conduction over that of widely applied hexagonal 4H-SiC. Moreover, much lower concentration of interfacial traps between insulating oxide gate and 3C-SiC helps fabricate reliable and long-life devices like metal-oxide-semiconductor field effect transistors. However, the growth of high-quality and wafer-scale 3C-SiC crystals has remained a big challenge up to now despite decades-long efforts by researchers because of its easy transformation into other polytypes during growth, limiting the development of 3C-SiC-based devices. Herein, we report that 3C-SiC can be made thermodynamically favored from nucleation to growth on a 4H-SiC substrate by top-seeded solution growth technique, beyond what is expected by classical nucleation theory. This enables the steady growth of high-quality and large-size 3C-SiC crystals (2–4-inch in diameter and 4.0–10.0 mm in thickness) sustainable. The as-grown 3C-SiC crystals are free of other polytypes and have high-crystalline quality. Our findings broaden the mechanism of hetero-seed crystal growth and provide a feasible route to mass production of 3C-SiC crystals, offering new opportunities to develop power electronic devices potentially with better performances than those based on 4H-SiC.

The high voltage required to overcome the thermodynamic threshold and the complicated kinetics of the water splitting reaction limit the efficiency of single semiconductor-based photoelectrochemistry. A semiconductor/solar cell tandem structure has been theoretically demonstrated as a viable path to achieve an efficient direct transformation of sunlight into chemical energy. However, compact designs exhibiting the indispensable optimally balanced light absorption have not been demonstrated. In the current work, we design and implement a compact tandem providing the complementary absorption of a highly transparent BiVO₄ photoanode and a PM6:Y6 solar cell. Such bandgap combination approaches the optimal to reach the solar-to-hydrogen (STH) conversion upper limit for tandem photoelectrochemical cells (PECs). We demonstrate that, by using a photonic multilayer structure to adequately balance sunlight absorption among both tandem materials, a 25% increase in the bias-free STH conversion can be achieved, setting a clear path to take compact tandem PECs to the theoretical limit performance.

Two-dimensional materials have been widely used to tune the growth and energy-level alignment of perovskites. However, their incomplete passivation and chaotic usage amounts are not conducive to the preparation of high-quality perovskite films. Herein, we succeeded in obtaining higher-quality CsPbBr₃ films by introducing large-area monolayer graphene as a stable physical overlay on top of TiO₂ substrates. Benefiting from the inert and atomic smooth graphene surface, the CsPbBr₃ film grown on top by the van der Waal epitaxy has higher crystallinity, improved (100) orientation, and an average domain size of up to 1.22 µm. Meanwhile, a strong downward band bending is observed at the graphene/perovskite interface, improving the electron extraction to the electron transport layers (ETL). As a result, perovskite film grown on graphene has lower photoluminescence (PL) intensity, shorter carrier lifetime, and fewer defects. Finally, a photovoltaic device based on epitaxy CsPbBr₃ film is fabricated, exhibiting power conversion efficiency (PCE) of up to 10.64% and stability over 2000 h in the air.

The electrochemical performance of microsupercapacitors with graphene electrodes is reduced by the issue of graphene sheets aggregation, which limits electrolyte ions penetration into electrode. Increasing the space between graphene sheets in electrodes facilitates the electrolyte ions penetration, but sacrifices its electronic conductivity which also influences the charge storage ability. The challenging task is to improve the electrodes’ electronic conductivity and ionic diffusion simultaneously, boosting the device’s electrochemical performance. Herein, we experimentally realize the enhancement of both electronic conductivity and ionic diffusion from 2D graphene nanoribbons assisted graphene electrode with porous layer-upon-layer structure, which is tailored by graphene nanoribbons and self-sacrificial templates ethyl cellulose. The designed electrode-based device delivers a high areal capacitance of 71 mF cm^-2 and areal energy density of 9.83 µWh cm^-2, promising rate performance, outstanding cycling stability with 97% capacitance retention after 20 000 cycles, and good mechanical properties. The strategy paves the way for fabricating high-performance graphene-based MSCs.

SnO₂, with its high theoretical capacity, abundant resources, and environmental friendliness, is widely regarded as a potential anode material for lithium-ion batteries (LIBs). Nevertheless, the coarsening of the Sn nanoparticles impedes the reconversion back to SnO₂, resulting in low coulombic efficiency and rapid capacity decay. In this study, we fabricated a heterostructure by combining SnO₂ nanoparticles with MoS₂ nanosheets via plasma-assisted milling. The heterostructure consists of in-situ exfoliated MoS₂ nanosheets predominantly in 1 T phase, which tightly encase the SnO₂ nanoparticles through strong bonding. This configuration effectively mitigates the volume change and particle aggregation upon cycling. Moreover, the strong affinity of Mo, which is the lithiation product of MoS₂, toward Sn plays a pivotal role in inhibiting the coarsening of Sn nanograins, thus enhancing the reversibility of Sn to SnO₂ upon cycling. Consequently, the SnO₂/MoS₂ heterostructure exhibits superb performance as an anode material for LIBs, demonstrating high capacity, rapid rate capability, and extended lifespan. Specifically, discharged/charged at a rate of 0.2 A g^-1 for 300 cycles, it achieves a remarkable reversible capacity of 1173.4 mAh g^-1. Even cycled at high rates of 1.0 and 5.0 A g^-1 for 800 cycles, it still retains high reversible capacities of 1005.3 and 768.8 mAh g^-1, respectively. Moreover, the heterostructure exhibits outstanding electrochemical performance in both full LIBs and sodium-ion batteries.

The emergence of polymerized small molecule acceptors (PSMAs) has significantly improved the performance of all-polymer solar cells (all-PSCs). However, the pace of device engineering lacks behind that of materials development, so that a majority of the PSMAs have not fulfilled their potentials. Furthermore, most high-performance all-PSCs rely on the use of chloroform as the processing solvent. For instance, the recent high-performance PSMA, named PJ1-γ, with high LUMO, and HOMO levels, could only achieve a PCE of 16.1% with a high-energy-level donor (JD40) using chloroform. Herein, we present a methodology combining sequential processing (SqP) with the addition of 0.5%wt PC₇₁BM as a solid additive (SA) to achieve an impressive efficiency of 18.0% for all-PSCs processed from toluene, an aromatic hydrocarbon solvent. Compared to the conventional blend-casting (BC) method whose best efficiency (16.7%) could only be achieved using chloroform, the SqP method significantly boosted the device efficiency using toluene as the processing solvent. In addition, the donor we employ is the classic PM6 that has deeper energy levels than JD40, which provides low energy loss for the device. We compare the results with another PSMA (PYF-T-o) with the same method. Finally, an improved photostability of the SqP devices with the incorporation of SA is demonstrated.

The Fe-based anode of sodium-ion batteries attracts much attention due to the abundant source, low-cost, and high specific capacity. However, the low electron and ion transfer rate, poor structural stability, and shuttle effect of NaS₂ intermediate restrain its further development. Herein, the Fe₃O₄/Fe/FeS tri-heterojunction node spawned N-carbon nanotube scaffold structure (FHNCS) was designed using the modified MIL-88B(Fe) as a template followed by catalytic growth and sulfidation process. During catalytic growth process, the reduced Fe monomers catalyze the growth of N-doped carbon nanotubes to connect the Fe₃O₄/Fe/FeS tri-heterojunction node, forming a 3D scaffold structure. Wherein the N-doped carbon promotes the transfer of electrons between Fe₃O₄/Fe/FeS particles, and the tri-heterojunction facilitates the diffusion of electrons at the interface, to organize a 3D conductive network. The unique scaffold structure provides more active sites and shortens the Na⁺ diffusion path. Meanwhile, the structure exhibits excellent mechanical stability to alleviate the volume expansion during circulation. Furthermore, the Fe in Fe₃O₄/Fe heterojunction can adjust the d-band center of Fe in Fe₃O₄ to enhance the adsorption between Fe₃O₄ and Na₂S intermediate, which restrains the shuttle effect. Therefore, the FHNCS demonstrates a high specific capacity of 436 mAh g^-1 at 0.5 A g^-1, 84.7% and 73.4% of the initial capacities are maintained after 100 cycles at 0.5 A g^-1 and 1000 cycles at 1.0 A g^-1. We believe that this strategy gives an inspiration for constructing Fe-based anode with excellent rate capability and cycling stability.

The development of self-charging supercapacitor power cells (SCSPCs) has profound implications for smart electronic devices used in different fields. Here, we epitaxially electrodeposited Mo- and Fe-codoped MnO₂ films on piezoelectric ZnO nanoarrays (NAs) grown on the flexible carbon cloth (denoted ZnO@Mo-Fe-MnO₂ NAs). A self-charging supercapacitor power cell device was assembled with the Mo- and Fe-codoped MnO₂ nanoarray electrode and poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-Trfe) piezoelectric film doped with BaTiO₃ (BTO) and carbon nanotubes (CNTs) (denoted PVDF-Trfe/CNTs/BTO). The self-charging supercapacitor power cell device exhibited an energy density of 30 µWh cm^-2 with a high power density of 40 mW cm^-2 and delivered an excellent self-charging performance of 363 mV (10 N) driven by both the piezoelectric ZnO nanoarrays and the poly(vinylidenefluoride-co-trifluoroethylene) piezoelectric film doped with BaTiO₃ and carbon nanotubes. More intriguingly, the device could also be self-charged by 184 mV due to residual stress alone and showed excellent energy conversion efficiency and low self-discharge rate. This work illustrates for the first time the self-charging mechanism involving electrolyte ion migration driven by both electrodes and films. A comprehensive analysis strongly confirmed the important contribution of the piezoelectric ZnO nanoarrays in the self-charging process of the self-charging supercapacitor power cell device. This work provides novel directions and insights for the development of self-charging supercapacitor power cells.

Lithium metal batteries (LMBs) and anode-free LMBs (AFLMBs) present a solution to the need for batteries with a significantly superior theoretical energy density. However, their adoption is hindered by low Coulombic efficiency (CE) and rapid capacity fading, primarily due to the formation of unstable solid electrolyte interphase (SEI) layer and Li dendrite growth as a result of uneven Li plating. Here, we report on the use of a stoichiometric Ti₃C₂T_x (S-Ti₃C₂T_x) MXene coating on the copper current collector to enhance the cyclic stability of an anode-free lithium metal battery. The S-Ti₃C₂T_x coating provides abundant nucleation sites, thereby lowering the overpotential for Li nucleation, and promoting uniform Li plating. Additionally, the fluorine (-F) termination of S-Ti₃C₂T_x participates in the SEI formation, producing a LiF-rich SEI layer, vital for stabilizing the SEI and improving cycle life. Batteries equipped with S-Ti₃C₂T_x@Cu current collectors displayed reduced Li consumption during stable SEI formation, resulting in a significant decrease in capacity loss. AFLMBs with S-Ti₃C₂T_x@Cu current collectors achieved a high initial capacity density of 4.2 mAh cm^-2, 70.9% capacity retention after 50 cycles, and an average CE of 98.19% in 100 cycles. This innovative application of MXenes in the energy field offers a promising strategy to enhance the performance of AFLMBs and could potentially accelerate their commercial adoption.

As the persistent concerns regarding sluggish reaction kinetics and insufficient conductivities of sulfur cathodes in all-solid-state Li–S batteries (ASSLSBs), numerous carbon additives and solid-state electrolytes (SSEs) have been incorporated into the cathode to facilitate ion/electron pathways around sulfur. However, this has resulted in a reduced capacity and decomposition of SSEs. Therefore, it is worth exploring neotype sulfur hosts with electronic/ionic conductivity in the cathode. Herein, we present a hybrid cathode composed of few-layered S/MoS₂/C nanosheets (<5 layers) that exhibits high-loading and long-life performance without the need of additional carbon additives in advanced ASSLSBs. The multifunctional MoS₂/C host exposes the abundant surface for intimate contacting sites, in situ-formed Li_xMoS₂ during discharging as mixed ion/electron conductive network improves the S/Li₂S conversion, and contributes extra capacity for the part of active materials. With a high active material content (S + MoS₂/C) of 60 wt% in the S/MoS₂/C/Li₆PS₅Cl cathode composite (the carbon content is only ∼3.97 wt%), the S/MoS₂/C electrode delivers excellent electrochemical performance, with a high reversible discharge capacity of 980.3 mAh g^-1 (588.2 mAh g^-1 based on the whole cathode weight) after 100 cycles at 100 mA g^-1. The stable cycling performance is observed over 3500 cycles with a Coulombic efficiency of 98.5% at 600 mA g^-1, while a high areal capacity of 10.4 mAh cm^-2 is achieved with active material loading of 12.8 mg cm^-2.

Rechargeable lithium–sulfur (Li–S) batteries, featuring high energy density, low cost, and environmental friendliness, have been dubbed as one of the most promising candidates to replace current commercial rechargeable Li-ion batteries. However, their practical deployment has long been plagued by the infamous “shuttle effect” of soluble Li polysulfides (LiPSs) and the rampant growth of Li dendrites. Therefore, it is important to specifically elucidate the solvation structure in the Li–S system and systematically summarize the feasibility strategies that can simultaneously suppress the shuttle effect and the growth of Li dendrites for practical applications. This review attempts to achieve this goal. In this review, we first introduce the importance of developing Li–S batteries and highlight the key challenges. Then, we revisit the working principles of Li–S batteries and underscore the fundamental understanding of LiPSs. Next, we summarize some representative characterization techniques and theoretical calculations applied to characterize the solvation structure of LiPSs. Afterward, we overview feasible designing strategies that can simultaneously suppress the shuttle effect of soluble LiPSs and the growth of Li dendrites. Finally, we conclude and propose personal insights and perspectives on the future development of Li–S batteries. We envisage that this timely review can provide some inspiration to build better Li–S batteries for promoting practical applications.

Sodium-ion capacitors (SICs) have great potential in energy storage due to their low cost, the abundance of Na, and the potential to deliver high energy and power simultaneously. This article demonstrates a template-assisted method to induce graphitic nanodomains and micro-mesopores into nitrogen-doped carbons. This study elucidates that these graphitic nanodomains are beneficial for Na⁺ storage. The obtained N-doped carbon (As8Mg) electrode achieved a reversible capacity of 254 mA h g^–1 at 0.1 A g^–1. Moreover, the As8Mg-based SIC device achieves high combinations of power/energy densities (53 W kg^–1 at 224 Wh kg^–1 and 10 410 W kg^–1 at 51 Wh kg^–1) with outstanding cycle stability (99.7% retention over 600 cycles at 0.2 A g^–1). Our findings provide insights into optimizing carbon’s microstructure to boost sodium storage in the pseudocapacitive mode.

Grain boundaries (GBs) in perovskite polycrystalline films are the most sensitive place for the formation of the defect states and the accumulation of impurities. Thus, abundant works have been carried out to explore their properties and then try to solve the induced problems. Currently, two important issues remain. First, the role of GBs in charge carrier dynamics is unclear due to their component complexity/defect tolerance nature and the insufficiency in testing accuracy. Some works conclude that GBs are benign, while others consider GBs as carrier recombination centers. Things for sure are the deterioration in ion transport and perovskite decomposition. Second, to solve the known hazards of GBs, a lot of additives have been added to anchoring ions and passivate defects. But in most of those works, GBs and perovskite surfaces are treated in the same manner ignoring the fact that GB is essentially a homogeneous junction in a narrow and slender space, while surface is a heterogeneous junction with a stratified structure. In this review, we focus on works insight into GBs and additives for them. Additionally, we also discuss the prospects of the maturity of GB exploration toward upscaling the manufacture of perovskite photovoltaic and related optoelectronic devices.

Traditional heat conductive epoxy composites often fall short in meeting the escalating heat dissipation demands of large-power, high-frequency, and high-voltage insulating packaging applications, due to the challenge of achieving high thermal conductivity (k), desirable dielectric performance, and robust thermomechanical properties simultaneously. Liquid crystal epoxy (LCE) emerges as a unique epoxy, exhibiting inherently high k achieved through the self-assembly of mesogenic units into ordered structures. This characteristic enables liquid crystal epoxy to retain all the beneficial physical properties of pristine epoxy, while demonstrating a prominently enhanced k. As such, liquid crystal epoxy materials represent a promising solution for thermal management, with potential to tackle the critical issues and technical bottlenecks impeding the increasing miniaturization of microelectronic devices and electrical equipment. This article provides a comprehensive review on recent advances in liquid crystal epoxy, emphasizing the correlation between liquid crystal epoxy’s microscopic arrangement, organized mesoscopic domain, k, and relevant physical properties. The impacts of LC units and curing agents on the development of ordered structure are discussed, alongside the consequent effects on the k, dielectric, thermal, and other properties. External processing factors such as temperature and pressure and their influence on the formation and organization of structured domains are also evaluated. Finally, potential applications that could benefit from the emergence of liquid crystal epoxy are reviewed.

Solid-state lithium batteries (SSLBs) with high safety have emerged to meet the increasing energy density demands of electric vehicles, hybrid electric vehicles, and portable electronic devices. However, the dendrite formation, high interfacial resistance, and deleterious interfacial reactions caused by solid–solid contact between electrode and electrolyte have hindered the commercialization of SSLBs. Thus, in this review, the state-of-the-art developments in the rational design of solid-state electrolyte and their progression toward practical applications are reviewed. First, the origin of interface instability and the sluggish charge carrier transportation in solid–solid interface are presented. Second, various strategies toward stabilizing interfacial stability (reducing interfacial resistance, suppressing lithium dendrites, and side reactions) are summarized from the physical and chemical perspective, including building protective layer, constructing 3D and gradient structures, etc. Finally, the remaining challenges and future development trends of solid-state electrolyte are prospected. This review provides a deep insight into solving the interfacial instability issues and promising solutions to enable practical high-energy-density lithium metal batteries.

Lithium–sulfur batteries (LSBs) are widely regarded as promising next-generation batteries due to their high theoretical specific capacity and low material cost. However, the practical applications of LSBs are limited by the shuttle effect of lithium polysulfides (LiPSs), electronic insulation of charge and discharge products, and slow LiPSs conversion reaction kinetics. Accordingly, the introduction of catalysts into LSBs is one of the effective strategy to solve the issues of the sluggished LiPS conversion. Because of their nearly 100% atom utilization and high electrocatalytic activity, single-atom catalysts (SACs) have been widely used as reaction mediators for LSBs’ reactions. Excitingly, the SACs with asymmetric coordination structures have exhibited intriguing electronic structures and superior catalytic activities when compared to the traditional M–N₄ active sites. In this review, we systematically describe the recent advancements in the installation of asymmetrically coordinated single-atom structure as reactions catalysts in LSBs, including asymmetrically nitrogen coordinated SACs, heteroatom coordinated SACs, support effective asymmetrically coordinated SACs, and bimetallic coordinated SACs. Particularly noteworthy is the discussion of the catalytic conversion mechanism of LiPSs spanning asymmetrically coordinated SACs. Finally, a perspective on the future developments of asymmetrically coordinated SACs in LSB applications is provided.

Organosulfur materials containing sulfur–sulfur bonds are an emerging class of high-capacity cathodes for lithium storage. However, it remains a great challenge to achieve rapid conversion reaction kinetics at practical testing conditions of high cathode mass loading and low electrolyte utilization. In this study, a Li-rich pyrolyzed polyacrylonitrile/selenium disulfide (pPAN/Se₂S₃) composite cathode is synthesized by deep lithiation to address the above challenges. The Li-rich molecular structure significantly boosts the lithium storage kinetics by accelerating lithium diffusivity and improving electronic conductivity. Even under practical test conditions requiring a lean electrolyte (Electrolyte/sulfur ratio of 4.1 µL mg^-1) and high loading (7 mg cm^-2 of pPAN/Se₂S₃), DL-pPAN/Se₂S₃ exhibits a specific capacity of 558 mAh g^-1, maintaining 484 mAh g^-1 at the 100th cycle with an average Coulombic efficiency of near 100%. Moreover, it provides (electro)chemically stable Li resources to offset Li consumption over charge–discharge cycles. As a result the as-fabricated anode-free cell shows a superior cycling stability with 90% retention of the initial capacity over 45 cycles. This study provides a novel approach for fabricating high-energy and stable Li–SPAN cells.

Growing energy demand drives the rapid development of clean and reliable energy sources. In the past years, the exploration of novel materials with considerable efficiency and durability has drawn attention in the area of electrochemical energy conversion. Transition metal macrocyclic metallophthalocyanines (MPcs)-based catalysts with a peculiar 2D constitution have emerged with a promising future account of their highly structural tailorability and molecular functionality which greatly extend their functionalities as electrocatalytic materials for energy conversion. This review summarizes the systematic engineering of synthesis of MPcs and their analogs in detail, and mostly pays attention to the frontier research of MPc-based high-performance catalysts toward different electrocatalytic processes concerning hydrogen, oxygen, water, carbon dioxide, and nitrogen, with a particular focus on discussing the interrelationship between the electrocatalytic activity and component/structure, as well as functional applications of MPcs. Finally, we give the gaps that need to be addressed after much thought.

Thermo-electro-magnetic materials with simultaneously large magnetocaloric (MC) and thermoelectric (TE) effects are the core part for designing TE/MC all-solid-state cooling devices. Compositing MC phase with TE material is an effective approach. However, the elemental diffusion and chemical reaction occurring at the two-phase interfaces could significantly impair the cooling performance. Herein, Gd/Bi_0.5Sb_1.5Te₃ (Gd/BST) composites were prepared by a low-temperature high-pressure spark plasma sintering method with an aim to control the extent of interfacial reaction. The reaction of Gd with the diffusive Te and the formation of GdTe nanocrystals were identified at the Gd/BST interfaces by the atomic-resolution microscope. The formed BiTe’ antisite defects and enhanced {000 l} preferential orientation in BST are responsible for the increased carrier concentration and mobility, which leads to optimized electrical properties. The heterogeneous interface phases, along with antisite defects, favor the phonon scattering enhancement and lattice thermal conductivity suppression. The optimized composite sintered at 693 K exhibited a maximum ZT of 1.27 at 300 K. Furthermore, the well-controlled interfacial reaction has a slight impact on the magnetic properties of Gd and a high magnetic entropy change is retained in the composites. This work provides a universal approach to fabricating thermo-electro-magnetic materials with excellent MC and TE properties.