The remarkable successes of graphene have sparked increasing interest in elemental two-dimensional (2D) materials, also referred to as Xenes. Due to their chemical simplicity and appealing physiochemical properties, Xenes have shown particular potential for numerous (opto) electronic, iontronic, and energy applications. Among them, layered α-phase tellurene has demonstrated the most promise, thanks to the recent successes in the chemical synthesis of highly crystalline 2D tellurene. However, the general electronic and electrochemical properties of tellurene in electrolyte systems remain ambiguous, hindering their further development. In this work, we studied the electrostatic gating, electrocatalysis, and electrochemical stability of tellurene in electrolyte systems. Our results show that tellurene obtained from both hydrothermal and chemical vapor deposition methods, two mainstream synthetic approaches for Xenes, demonstrates thickness-dependent ambipolar transport with high hole mobility and stability in both aqueous electrolytes and ionic liquids. More importantly, the electrochemical properties of tellurene are investigated via the emerging on-chip electrochemistry. Pristine tellurene demonstrates hydrogen evolution reaction with low Tafel slopes and remarkable electrochemical stability in acidic electrolytes over a large potential window. Our study provides a comprehensive understanding of the iontronic and electrochemical properties of tellurene, paving the way for the broad adoption of Xenes in sensors, synaptic devices, and electrocatalysis.

Conductive-bridge random access memory (CBRAM) emerges as a promising candidate for next-generation memory and storage device. However, CBRAMs are prone to degenerate and fail during electrochemical metallization processes. To address this issue, herein we propose a self-repairability strategy for CBRAMs. Amorphous NbSe₂ was designed as the resistive switching layer, with Cu and Au as the top and bottom electrodes, respectively. The NbSe₂ CBRAMs demonstrate exceptional cycle-to-cycle and device-to-device uniformity, with forming-free and compliance current-free resistive switching characteristics, low-operation voltage, and competitive endurance and retention performance. Most importantly, the self-repairable behavior is discovered for the first time in CBRAM. The device after failure can recover its performance to the initially normal state by operating with a slightly large reset voltage. The existence of Cu conductive filament and excellent controllability of Cu migration in the NbSe₂ switching layer has been revealed by a designed broken-down point approach, which is responsible for the self-repairable behavior of NbSe₂ CBRAMs. Our self-repairable and high-uniform amorphous NbSe₂ CBRAM may open the door to the development of memory and storage devices in the future.

Transition metal carbides, including both MXene and non-MXene metal carbides, have enjoyed a soaring reputation in recent years. Benefitting from their intriguing physical and chemical characteristics, they shine in multifarious research fields and currently, they have emerged as promising nanomaterials for photocatalysis in energy and environmental science. Herein, based on the recent theoretical research and experimental studies, a systematic and comprehensive review of the expeditious advances of metal carbides and their nano-architectures in the flourishing arena of photocatalysis is presented. The fundamental mechanism involved in photocatalysis with metal carbides serving as semiconductors or cocatalysts is thoroughly discussed. Besides, we highlight the main synthetic strategies of MXene and non-MXene metal carbides and unravel the structural properties of the as-obtained metal carbides via different fabrication routes to establish and elucidate their intriguing role in ameliorating photocatalytic activity. Moreover, the state-of-the-art advancements of metal carbides in diverse photocatalytic applications, including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, and carbon dioxide reduction reaction, are summarized. In particular, insights into the structure–activity relationship of metal carbide in photocatalysis are elucidated. Finally, this review concludes with the ongoing challenges and perspectives on the future directions of metal carbides in the realm of photocatalysis.

Polymer ionogel (PIG) is a new type of flexible, stretchable, and ion-conductive material, which generally consists of two components (polymer matrix materials and ionic liquids/deep eutectic solvents). More and more attention has been received owing to its excellent properties, such as nonvolatility, good ionic conductivity, excellent thermal stability, high electrochemical stability, and transparency. In this review, the latest research and developments of PIGs are comprehensively reviewed according to different polymer matrices. Particularly, the development of novel structural designs, preparation methods, basic properties, and their advantages are respectively summarized. Furthermore, the typical applications of PIGs in flexible ionic skin, flexible electrochromic devices, flexible actuators, and flexible power supplies are reviewed. The novel working mechanism, device structure design strategies, and the unique functions of the PIG-based flexible ionic devices are briefly introduced. Finally, the perspectives on the current challenges and future directions of PIGs and their application are discussed.

Hybrid perovskites have attracted enormous attention in the next generation resistive switching (RS) memristor for the artificial synapses, owing to their ambipolar charge transport, long diffusion length, and tunable visible bandgap. However, the variable switch, limited reproducibility, and poor endurance are the obstacles to the practical application of the perovskite memristors. Herein, we reported a multilevel RS nonvolatile memory based on a 3D trigonal HC(NH₂)₂PbI₃ (α-FAPbI₃) perovskite layer modified by 1-cyanobutyl-3-methylimidazolium chloride ([CNBmim]Cl) and sandwiched between ITO and Au electrodes (Au/[CNBmim]Cl/α-FAPbI₃/SnO₂/ITO). In contrast to the bare memristor with failure switching from low resistance state (LRS) to high resistance state (HRS), the memristor device based on the α-FAPbI₃ modified with [CNBmim]Cl (Target device) shows the retention time over 10⁴ s with On/Off ratio (>10²) and endurance up to 550 cycles. The stable RS cycle benefits from the accelerated electrons de-trapping from the reduced defects and fast charge separation in the interface of α-FAPbI₃/electrode, leading to the rupture of conductive filaments and transition of LRS to HRS. As a two-terminal analog synaptic device, the target device can realize random handwritten digit recognition with an impressive accuracy of 89.3% on the condition of low learning phases (500 training cycles).

Development and understanding of highly mechanically robust and electronically conducting hydrogels are extremely important for ever-increasing energy-based applications. Conventional mixing/blending of conductive additives with hydrophilic polymer network prevents both high mechanical strength and electronic conductivity to be presented in polymer hydrogels. Here, we proposed a double-network (DN) engineering strategy to fabricate PVA/PPy DN hydrogels, consisting of a conductive PPy-PA network via in-situ ultrafast gelation and a tough PVA network via a subsequent freezing/thawing process. The resultant PVA/PPy hydrogels exhibited superior mechanical and electrochemical properties, including electrical conductivity of ~6.8 S/m, mechanical strength of ~0.39 MPa, and elastic moduli of ~0.1 MPa. Upon further transformation of PVA/PPy hydrogels into supercapacitors, they demonstrated a high capacitance of ~280.7 F/g and a cycle life of 2000 galvanostatic charge/discharge cycles with over 94.3% capacity retention at the current density of 2 mA/cm² and even subzero temperatures of −20 °C. Such enhanced mechanical performance and electronic conductivity of hydrogels are mainly stemmed from a synergistic combination of continuous electrically conductive PPy-PA network and the two interpenetrating DN structure. This in-situ gelation strategy is applicable to the integration of ionic-/electrical-conductive materials into DN hydrogels for smart-soft electronics, beyond the most commonly used PEDOT:PSS-based hydrogels.

Booming sophisticated robotics and prosthetics put forward high requirements on soft conductive materials that can bridge electronics and biology, those soft conductive materials should imitate the mechanical properties of biological tissues and build information transmission networks. Until now, it remains a great challenge to handle the trade-off among ease of preparation, high conductivity, processability, mechanical adaptability, and external stimuli responsiveness. Herein, a kind of readily prepared and processed multifunctional MXene nanocomposite hydrogel is reported, which is prepared via the fast gelation of cationic monomer initiated by delaminated MXene sheets. The gelation time can be adjusted (several seconds to minutes) based on the MXene loadings. By adjusting the MXene ratio, the resulting nanocomposites are ultrastretchable (>5000%), three-dimensional (3D) printable, and show outstanding mechanical and electrical self-healing. As expected, the integration of multifunctional systems onto various substrates (e.g., gloves and masks) is further demonstrated via 3D printing and could achieve diverse sensory capabilities toward strain, pressure, and temperature, showing great prospects as smart flexible electronics.

Thermochromic smart windows have gained increasing popularity in light modulation and energy management in buildings. However, the fabrication of flexible thermochromic smart windows with high luminous transmittance (T_lum), tailorable critical temperature (τ_c), strong solar modulation ability (ΔT_sol), and long-term durability remains a huge challenge. In this study, hydrogel-based thermochromic smart windows are fabricated by sandwiching thermochromic hydrogels of polyallylamine hydrochloride, polyacrylic acid, and carbonized polymer dots (CPDs) complexes between two pieces of transparent substrates. Benefiting from the incorporation of nanosized CPDs, the thermochromic hydrogel has an ultrahigh T_lum of ~98.7%, a desirable τ_c of ~24.2 °C, a ΔT_sol of ~89.3% and a rapid transition time of ~3 s from opaque state to transparent state. Moreover, the thermochromic hydrogel exhibits excellent anti-freezing ability, tight adhesion toward various substrates, and excellent self-healing capability. The self-healing capability enables the fabrication of large-area smart windows by welding multiple hydrogel pieces. The smart windows retain their original thermochromic properties after being stored under ambient conditions for at least 147 days or undergoing 10,000 uninterrupted heating/cooling cycles. The model houses with smart windows can achieve a temperature reduction of 9.2 °C, demonstrating the excellent indoor temperature modulation performance of the smart windows.

Research and development of novel fluorine-free materials to replace fluorinated aqueous film-forming foam (AFFF) are crucial for improving pool fire suppression performance and protecting the environment. In this study, we report the thermo-responsive fluorine-free foam stabilized by triblock PEO–PPO–PEO copolymers (EO)₁₀₀(PO)₆₅(EO)₁₀₀ for pool fire suppression. Small-angle X-ray scattering (SAXS) and reflected light interferometric techniques are conducted to study the molecular self-assembly in bulk and film thinning behavior, and the foaming kinetics of copolymer solution and thermophysical properties of the liquid foam are studied by dynamic surface tension and oscillatory rheology analysis. At room temperature, the amphipathic structure of PEO–PPO–PEO makes it possible to absorb at the air–liquid interface forming large-scale liquid foams containing the mobile films with a detergent state. Upon heating to the surface cooling temperature of burning oil, the mobile films can be actively switched into mechanically strong films with rigid surfaces. The in situ switching of the two interfacial states leads to the significant enhancement of the foam stability, especially under the dual defoaming effects of heat and oil. What's more, it is observed that the confinement of organized copolymer micelles in the Plateau borders and micellar self-layering in film confinement induce drainage delay of foam and film's stepwise thinning phenomenon, further increasing film thickness and enhancing the thermal stability of the foam. In standard fire-fighting tests, it is proved that the burnback performance exhibited by thermo-responsive copolymer foams is three times better than that for classical fluorine-free foams and almost 1.5 times higher than that for commercial AFFF.

Despite extensive efforts in designing and preparing switchable underwater adhesives, it is not easy to regulate the underwater adhesion strength locally and remotely. Here, we design and synthesize photoreversible copolymer of poly[dopamine methacrylamide-co-methoxyethyl-acrylate-co-7-(2-methacryloyloxyethoxy)-4-methylcoumarin]. Due to the dynamic formation and breaking of chemical crosslinking networks within the smart adhesives, the material shows widely tunable adhesion strength from ∼150 to ∼450 kPa and long-range reversible maneuverability under orthogonal 254 and 365 nm ultraviolet light stimulation via the coumarin dimerization and cycloreversion. Moreover, the adhesive exhibits good circulation performance and stability in an acid–base environment. It also demonstrated that the bolt can be coated with the smart adhesive material for on-demand bonding. This design principle opens the door to the development of remotely controllable high-performance smart underwater adhesives.

This study marks the birth of visible and selective click covalent assembly. It is achieved by amplifying orthogonal alkyne−azide click chemistry through interfacial multisite interactions between azide/alkyne functionalized polymer hydrogels. Macroscopic assembly of hydrogels via host−guest chemistry or noncovalent interactions such as electrostatic interactions has been reported. Unlike macroscopic supramolecular assembly, here we report visible and selective “click” covalent assembly of hydrogels at the macroscale. LEGO-like hydrogels modified with alkyne and azide groups, respectively, can click together via the formation of covalent bonds. Monomer concentration-dependent assembly and selective covalent assembly have been studied. Notably, macroscopic gel assembly clearly elucidates click preferences and component selectivity not observed in the solution reactions of competing monomers.

Patterning diversified properties and surface structure of polymer materials are of great importance toward their potential in biology, optics, and electronics. However, achieving both the patternability of stiffness and microstructure in a reconfigurable manner remains challenging. Here, we prepare amphigels crosslinked by dynamic disulfide bonds, which can be reversibly swollen by immiscible water or liquid paraffin. In the paraffingel form, the materials exhibited a high modulus of 130 MPa due to densified hydrogen bonds. Whereas swollen by water, the modulus fell over two orders of magnitude owing to the destruction of the hydrogen bonds. Via regionalized swelling of the solvents, well-controlled and rewritable soft/stiff mechanical patterns can be created. On the other hand, the dynamic exchange of the disulfide crosslinking enables mechanophoto patterning to fabricate sophisticated macrogeometries and microstructures. The reconfigurable stiffness-structure patterning can be manipulated orthogonally, which will create more application opportunities beyond conventional hydrogels and organogels.

Aqueous zinc-ion batteries (ZIBs) have attracted extensive interest for the next-generation batteries, which, however, are facing great challenges due to the poor reversibility of zinc (Zn) anodes and side reactions of water decomposition. Herein, we demonstrated a strategy that the solvation sheath of Zn ions could be facilely regulated by supramolecular coordination chemistry by adding small amounts of cyclodextrins (CDs) and, hence, inhibited the side reactions and side products, widened the electrochemical window, facilitated the homogenous deposition of Zn ions, refined the Zn grains, and enhanced the stability of Zn anodes. Importantly, we demonstrated that compared with α- and β-CD, the γ-CD showed the best regulation effect of the solvation sheath of Zn ions either at the same molar ratio or at the same mass concentration, which could be ascribed to their difference in supramolecular coordination chemistry and the strongest interaction of γ-CD with Zn ions. As a result, with γ-CD, the Zn//Zn symmetric cells showed ultrahigh stability with a cycling lifespan of over 2400 h at a current density of 1 mA/cm². These results highlight the regulation of solvation sheath by supramolecular coordination chemistry for highly stable Zn anodes and pave a new way to realize high-performance ZIBs.

As one of the major causes of antimicrobial resistance, β-lactamase develops rapidly among bacteria. Detection of β-lactamase in an efficient and low-cost point-of-care testing (POCT) way is urgently needed. However, due to the volatile environmental factors, the quantitative measurement of current POCT is often inaccurate. Herein, we demonstrate an artificial intelligence (AI)-assisted mobile health system that consists of a paper-based β-lactamase fluorogenic probe analytical device and a smartphone-based AI cloud. An ultrafast broad-spectrum fluorogenic probe (B1) that could respond to β-lactamase within 20 s was first synthesized, and the detection limit was determined to be 0.13 nmol/L. Meanwhile, a three-dimensional microfluidic paper-based analytical device was fabricated for integration of B1. Also, a smartphone-based AI cloud was developed to correct errors automatically and output results intelligently. This smart system could calibrate the temperature and pH in the β-lactamase level detection in complex samples and mice infected with various bacteria, which shows the problem-solving ability in interdisciplinary research, and demonstrates potential clinical benefits.

Polyimides externally deployed in spacecraft or satellites extensively have various aerospace hazards, including atomic oxygen (AO) erosion, irradiation degradation, and electrostatic charge/discharge (ESC/ESD). To cope with these challenges, we fabricate a ZnO/CuNi-polyimide composite film with augmented permanence. Using spectroscopy and microscopy techniques, we have shown that the combination of chelation and cross-linking in the interfacial architecture leads to enhanced interfacial compatibility and mechanical robustness. Besides, due to the positive AO diffusion barrier ability of the wurtzite ZnO, our composite film shows remarkable AO resistance and a very small E_y value of 6.88 × 10⁻²⁶ cm³/atom, which is merely 2.29% of that of pristine polyimide. Moreover, the well-defined nanocrystalline state with minimal lattice swelling (0.3%–0.7%) of the Fe⁺-irradiated ZnO/CuNi-polyimide at a damaging dose of 353.4 dpa demonstrates its excellent irradiation resistance. Finally, the ZnO/CuNi-polyimide also shows sufficient electrostatic dissipation capacity to cope with the ESC/ESD events. Our fabrication approach for composite films based on multi-technology integration shows potential for aerospace applications and deployment.

Herein, we fabricated a flexible semidry electrode with excellent mechanical performance, satisfactory self-adhesiveness, and low-contact impedance using physical/chemical crosslinked polyvinyl alcohol/polyacrylamide dual-network hydrogels (PVA/PAM DNHs) as an efficient saline reservoir. The resultant PVA/PAM DNHs showed admirable adhesive and compliance to the hairy scalp, facilitating the establishment of a robust electrode/skin interface for biopotential signal transmission. Moreover, the PVA/PAM DNHs steadily released trace saline onto the scalp to achieve the minimized potential drift (1.47 ± 0.39 mV/min) and low electrode–scalp impedance (18.2 ± 8.9 kΩ @ 10 Hz). More importantly, the application feasibility of real-world brain−computer interfaces (BCIs) was preliminarily validated by 10 participants using two classic BCI paradigms. The mean temporal cross-correlation coefficients between the semidry and wet electrodes in the eyes open/closed and the N200 speller paradigms are 0.919 ± 0.054 and 0.912 ± 0.050, respectively. Both electrodes demonstrate anticipated neuroelectrophysiological responses with similar patterns. This semidry electrode could also effectively capture robust P-QRS-T peaks during electrocardiogram recording. Considering their outstanding advantages of fast setup, user-friendliness, and robust signals, the proposed PVA/PAM DNH-based electrode is a promising alternative to wet electrodes in biopotential signal acquisition.

Biomimetic intelligent polymeric hydrogel actuators with cooperative fluorescence-color switchable behaviors are expected to find great potential applications in soft robotics, visual detection/display, and camouflage applications. However, it remains challenging to realize the spatial manipulation of synergistic shape/color-changing behaviors. Herein, we report an interfacial supramolecular assembly (ISA) approach that enables the construction of robust fluorescent polymeric hydrogel actuators with spatially anisotropic structures. On the basis of this ISA approach, diverse 2D/3D soft fluorescent hydrogel actuators, including chameleon- and octopi-shaped ones with spatially anisotropic structures, were facilely assembled from two different fluorescent hydrogel building blocks sharing the same physically cross-linked agar network. Spatially control over synergistic shape/color-changing behaviors was then realized in one single anisotropic hydrogel actuator. The proposed ISA approach is universal and expected to open promising avenues for developing powerful bioinspired intelligent soft actuators/robotics with selective spatial shape/color-changing behaviors.

Fluorescent poly(N-isopropylacrylamide-co-Nile blue) (pNIPAm-co-NB) microgels were synthesized that exhibited fluorescence intensity changes in a water temperature-dependent fashion. NB is well known to exhibit fluorescence intensity that depends on the hydrophobicity of the environment, while pNIPAm-based microgels are well known to transition from swollen (hydrophilic) to collapsed (relatively hydrophobic) at temperatures greater than 32 °C; hence, we attribute the above behavior to the hydrophobicity changes of the microgels with increasing temperature. This phenomenon is ultimately due to NB dimers (relatively quenched fluorescence) being broken in the hydrophobic environment of the microgels leading to relatively enhanced fluorescence. We went on to show that the introduction of cucurbit[7]uril (CB[7]) into the pNIPAm-co-NB microgels enhanced their fluorescence allowing them to be used for polyamine (e.g., spermine [SPM]) detection. Specifically, CB[7] forms a host–guest interaction with NB in the microgels, which prevents NB dimerization and enhances their fluorescence. When SPM is present, it forms a host–guest complex that is favored over the CB[7]-NB host–guest interaction, which frees the NB for dimerization and leads to fluorescence quenching. As a result, we could generate an SPM sensor capable of SPM detection down to ~0.5 µmol/L in complicated matrixes such as serum and urine.

Alloying is regarded as one of the most promising strategies for boosting performance of catalysts for hydrogen evolution reaction (HER) due to the adjustable electronic structure and intermediate adsorption. However, there is no theory (including d-band center theory) can accurately guide the preparation and design of alloy catalysts, and thus resulting all the reported alloy catalysts are obtained by time-consuming and laborious experimental exploration. Herein, we proposed a mean d-band center (ε_as) as a new accurate descriptor for alloy activity prediction. Theoretical simulation and experiment results revealed that this descriptor exhibits a strong scaling relation with H adsorption energy. Besides, the obtained Cu–Ag alloy displays an optimal overpotential of 223 mV at 10 mA/cm² in 0.5 mol/L H₂SO₄, which is more than 300 mV lower than those of pristine Cu (530 mV) and Ag (569 mV) powder. Our work provides a new idea toward designing highly efficient HER catalysts and broadens the applicability of d-band theory to activity prediction of alloys.

Conductive polymer hydrogels have greatly improved the compatibility of electronic devices with biological tissues for human–machine interfacing. Hydrogels that possess low Young's modulus, low interfacial impedance, and high tensile properties facilitate high-quality signal transmission across dynamic biointerfaces. Direct incorporation of elastomers with conductive polymers may result in undesirable mechanical and/or electrical performance. Here, a covalent cross-linking network and an entanglement-driven network with conductive poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) have been combined. The triple-network conductive hydrogel shows high stretchability (with fracture strain up to 900%), low impedance (down to 91.2 Ω·cm²), and reversible adhesion. Importantly, ultra-low modulus (down to 6.3 kPa) and strain-insensitive electrical/electrochemical performance were achieved, which provides a guarantee for low current stimulation. The material design will contribute to the progression of soft and conformal bioelectronic devices, and pave the way to future implantable electronics.

The combination of the first-line standard chemotherapeutic drug doxorubicin hydrochloride (DOX) and the molecular-targeted drug Herceptin (HCT) has emerged as a promising strategy for human epidermal growth receptor 2 (HER-2) overexpressing breast cancer treatment. However, insufficient drug accumulation and severe cardiotoxicity are two major challenges that limit its clinical application. Herein, an in situ forming gold nanorods (AuNRs)-sodium alginate (ALG) hybrid hydrogel encapsulating DOX and HCT was engineered for tumor synergistic therapy involving injectable, dual-stimuli-responsive drug release, photothermal ablation, and drug-antibody synergistic therapy. The photothermal agent AuNRs, anticancer drug DOX, and anticancer antibody HCT were mixed in ALG solution, and after injection, the soluble ALG was quickly transformed into a hydrogel in the presence of Ca²⁺ in the body. Significantly, the hybrid hydrogel exhibits an extremely high photothermal conversion efficiency of 70% under 808 nm laser irradiation. The thermal effect can also provide photothermal stimulation to trigger the drug release from the gel matrix. In addition, the drug release rate and the releasing degree are also sensitive to the pH. In vitro studies demonstrated that the PEI-AuNR/DOX/HCT/ALG hydrogel has facilitated the therapeutic efficiency of each payload and demonstrated a strong synergistic killing effect on SK-BR-3 cells. In vivo imaging results showed that the local drug delivery system can effectively reduce the nonspecific distribution in normal tissues and increase drug concentration at tumor sites. The proposed hydrogel system shows significant clinical implications by easily introducing a sustainable photothermal therapy and a potential universal carrier for the local delivery of multiple drugs to overcome the challenges faced in HER-2 overexpressing cancer therapy.

Traditional multicolor fluorescent hydrogels are generated through the assembly of discrete fluorescent hydrogels, which is not a complete integration much distinct from living organisms. On the basis of aggregation-induced emission (AIE), a special solvent polar-responsive AIE molecule possessing a twisted intramolecular charge transfer (TICT) effect was noticed. By incorporating it into the gel network, an AIE gel that displays continuous gradient fluorescence was fabricated. First, hydrogel A containing the solvent polar-responsive AIE-gen was prepared to show orange fluorescence. After soaking in the organic solvents, the fluorescence color transition of hydrogel A ranging from orange to green occurred when being immersed in high-polarity organic solvents ascribed to the embedded AIE-gen owning TICT effect. Then, hydrogel A was successively lifted up from organic solvents. Due to the different immersion time of each section for the hydrogel, the polarity difference occurred. Then, the produced gel B showed continuous gradient fluorescence ranging from orange to green under the irradiation of UV light.

Copper (Cu) has been regarded as a highly efficient electrocatalyst for the conversion of CO₂ into a multicarbon product. However, the catalytic mechanism and the active sites of Cu catalysts under operating conditions still remain elusive. Yang's team applied systematic operando characterization techniques to provide a quantitative analysis of the valence states and the chemical environment of Cu nanocatalysts under electrochemical reaction conditions, which clearly reveal the evolution of Cu nanocatalysts before and after the entire electrochemical CO₂ reduction.

Harvesting indoor light to power electronic devices for the Internet of Things has become an application scenario for emerging photovoltaics, especially utilizing organic photovoltaics (OPVs). Combined liquid- and solid-state processing, such as printing and lamination used in industry for developing indoor OPVs, also provides a new opportunity to investigate the device structure, which is otherwise hardly possible based on the conventional approach due to solvent orthogonality. This study investigates the impact of fullerene-based acceptor interlayer on the performance of conjugated polymer–fullerene-based laminated OPVs for indoor applications. We observe open-circuit voltage (V_OC) loss across the interface despite this arrangement being presumed to be ideal for optimal device performance. Incorporating insulating organic components such as polyethyleneimine (PEI) or polystyrene (PS) into fullerene interlayers decreases the work function of the cathode, leading to better energy level alignment with the active layer (AL) and reducing the V_OC loss across the interface. Neutron reflectivity studies further uncover two different mechanisms behind the V_OC increase upon the incorporation of these insulating organic components. The self-organized PEI layer could hinder the transfer of holes from the AL to the acceptor interlayer, while the gradient distribution of the PS-incorporated fullerene interlayer eliminates the thermalization losses. This work highlights the importance of structural dynamics near the extraction interfaces in OPVs and provides experimental demonstrations of interface investigation between solution-processed cathodic fullerene layer and bulk heterojunction AL.

Covalent organic framework (COF) materials have aroused tremendous interest in photocatalytic applications due to their tunable pore structure and photoelectric properties. The regular nanopore of COF itself presents a strongly confinement effect, which provides a unique regulatory effect for photons, electrons, protons, and other quantum-scale reaction groups. However, due to the weak surface electron coupling and transfer ability between the reactive groups and basic elements of its structural units, the activity of pure COFs photocatalyst is still not satisfactory. Therefore, the confinement modification strategy of confining low-dimension entities within COFs has been proposed, thus realizing new active sites construction and band structure regulation has been intensively studied, but yet to be summarized systematically. In this paper, the semi-conductivity of COFs is discussed dialectically based on photocatalytic thermodynamics, and the influence of internal linkage motifs and stacking behaviors on the band structure is collected. Then, the basic understanding of confinement characteristics and their influence on photocatalytic performance in dynamics is further explained according to the spatial dimension classification of low-dimension entities. And the application and mechanism of these COF-based confined catalysts in energy conversion reactions are discussed in detail. Lastly, the current challenges and development prospects of COF-based confined hetero-photocatalysts are discussed.