A heteronuclear dual transition metal atom catalyst is a promising strategy to solve and relieve the increasing energy and environment crisis. However, the role of each atom still does not efficiently differentiate due to the high activity but low detectability of each transition metal in the synergistic catalytic process when considering the influence of heteronuclear induced atomic difference for each transition metal atom, thus seriously hindering intrinsic mechanism finding. Herein, we proposed coordinate environment vary induced heterogenization of homonuclear dual-transition metal, which inherits the advantage of heteronuclear transition metal atom catalyst but also controls the variable of the two atoms to explore the underlying mechanism. Based on this proposal, employing density functional theory study and machine learning, 23 kinds of homonuclear transition metals are doping in four asymmetric C3N for heterogenization to evaluate the underlying catalytic mechanism. Our results demonstrate that five catalysts exhibit excellent catalytic performance with a low limiting potential of -0.28 to -0.48 V. In the meantime, a new mechanism, “capture–charge distribution–recapture–charge redistribution”, is developed for both side-on and end-on configuration. More importantly, the pronate site of the first hydrogenation is identified based on this mechanism. Our work not only initially makes a deep understanding of the transition dual metal-based heteronuclear catalyst indirectly but also broadens the development of complicated homonuclear dual-atom catalysts in the future.
The integrated technology of interfacial solar steam generation and photo-Fenton oxidation has emerged as a promising way to simultaneously mitigate freshwater scarcity and degrade organic pollutants. However, fabricating low-cost, multi-functional evaporators with high water evaporation and catalytic ability still presents a significant challenge. Herein, we report the functional upcycling of waste polyimide into semiconducting Fe-BTEC and subsequently construct Fe-BTEC-based composite evaporators for simultaneous freshwater production and photo-Fenton degradation of pollutants. Firstly, through a two-step solvothermal-solution stirring method, Fe-BTEC nanoparticles with the size of 20–100 nm are massively produced from waste polyimide, with a band gap energy of 2.2 eV. The composite evaporator based on Fe-BTEC and graphene possesses wide solar-spectrum absorption capacity, high photothermal conversion capacity, rapid delivery of water, and low enthalpy of evaporation. Benefiting from the merits above, the composite evaporator achieves a high evaporation rate of 2.72 kg m-2 h-1 from tetracycline solution, as well as the photothermal conversion efficiency of 97% when exposed to irradiation of 1 Sun, superior to many evaporators. What is more, the evaporator exhibits the tetracycline degradation rate of 99.6% with good recycling stability, ranking as one of the most powerful heterogeneous Fenton catalysts. COMSOL Multiphysics and density functional theory calculation results prove the synergistic effect of the concentrated heat produced by interfacial solar steam generation and catalytic active sites of Fe-BTEC on promoting H2O2 activation to form reactive oxidation radicals. This work not only provides a green strategy for upcycling waste polyimide, but also proposes a new approach to fabricate multi-functional evaporators.
A comprehensive understanding of the dynamic processes at the catalyst/electrolyte interfaces is crucial for the development of advanced electrocatalysts for the oxygen evolution reaction (OER). However, the chemical processes related to surface corrosion and catalyst degradation have not been well understood so far. In this study, we employ LiCoO2 as a model catalyst and observe distinct OER activities and surface stabilities in different alkaline solutions. Operando X-ray diffraction (XRD) and online mass spectroscopy (OMS) measurements prove the selective intercalation of alkali cations into the layered structure of LiCoO2 during OER. It is proposed that the dynamic cation intercalations facilitate the chemical oxidation process between highly oxidative Co species and adsorbed water molecules, triggering the so-called electrochemical-chemical reaction mechanism (EC-mechanism). The results of this study emphasize the influence of cations on OER and provide insights into new strategies for achieving both high activity and stability in high-performance OER catalysts.
Water often presents significant challenges in catalysts by deactivating active sites, poisoning the reaction, and even degrading composite structure. These challenges are amplified when the water participates as a reactant and is fed as a liquid phase, such as trickle bed-type reactors in a hydrogen-water isotope exchange (HIE) reaction. The key balance in such multiphase reactions is the precise control of catalyst design to repel bulk liquid water while diffusing water vapor. Herein, a platinum-incorporated metal-organic framework (MIL-101) based bifunctional hydrophobic catalyst functionalized with long alkyl chains (C12, dodecylamine) and further manufactured with poly(vinylidene fluoride), Pt@MIL-101-12/PVDF, has been developed which can show dramatically improved catalytic activity under multi-phase reactions involving hydrogen gas and liquid water. Pt@MIL-101-12/PVDF demonstrates enhanced macroscopic water-blocking properties, with a notable reduction of over 65% in water adsorption capacity and newly introduced liquid water repellency, while exhibiting a negligible increase in mass transfer resistance, i.e., bifunctional hydrophobicity. Excellent catalytic activity, evaluated via HIE reaction, and its durability underscore the impact of bifunctional hydrophobicity. In situ DRIFTS analysis elucidates water adsorption/desorption dynamics within the catalyst composite, highlighting reinforced water diffusion at the microscopic level, affirming the catalyst’s bifunctionality in different length scales. With demonstrated radiation resistance, Pt@MIL-101-12/PVDF emerges as a promising candidate for isotope exchange reactions.
The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development, thus garnering significant attention. In perovskite solar cells, the hole transport layer plays a crucial role. For the commonly employed organic small molecule hole transport material Spiro-OMeTAD, a certain period of oxidation treatment is required to achieve complete transport performance. However, this posttreatment oxidation processes typically rely on ambient oxidation, which poses challenges in terms of precise control and leads to degradation of the perovskite light absorption layer. This approach fails to meet the demands for high efficiency and stability in practical application. Herein, the mechanism of ultrafast laser on Spiro-OMeTAD and the reaction process for laser-induced oxidation of it are investigated. PbI2 at Perovskite/Spiro-OMeTAD interface breaks down to produce I2 upon ultrafast laser irradiation and I2 promote the oxidation process. Through the laser irradiation oxidation processing, a higher stability of perovskite solar cells is achieved. This work establishes a new approach toward oxidation treatment of Spiro-OMeTAD.
Organic cathode materials exhibit higher energy storage capacity, their poor cyclability due to dissolution in liquid organic electrolytes remains a challenge. However, recently, the electrochemical behavior of organopolysulfides incorporating N-heterocycles unveils promising cathode materials with stable cycling performance. Herein, the integration of organosulfides salt as cathodes with solid electrolytes, exemplified by sodium allyl(methyl)carbamodithioate and sodium diethylcarbamodithioate with a polymer solid electrolyte of polyethylene oxide and LiTFSI, addresses the poor electrochemical stability of organic electrodes. Comparative analysis highlights sodium allyl(methyl)carbamodithioate’s superior electrochemical performance and stability compared with sodium diethylcarbamodithioate, emphasizing the efficacy of periphery aliphatic modification in enhancing electrode capacity, rate performance, and electrochemical stability for organosulfide materials within all-solid-state lithium organic batteries. We also explore the origin of periphery aliphatic modification in these enhancing electrochemical performances by kinetic analysis and thermodynamic analysis. Furthermore, employing density functional theory calculations and ex situ FTIR experiments elucidates the critical role of the N–C=S structure in the energy storage mechanism. This research advances organic cathode design within organosulfide materials, unlocking the potential of all-solid-state lithium organic batteries with enhanced cyclability, propelling the development of next-generation energy storage systems.
Stretchability is a crucial property of flexible all-in-one supercapacitors. This work reports a novel hydrogel electrolyte, polyacrylamide-divinylbenzene-Li2SO4 (PAM-DVB-Li) synthesized by using a strategy of combining hydrophobic nodes and hydrophilic networks as well as a method of dispersing hydrophobic DVB crosslinker to acrylamide monomer/Li2SO4 aqueous solution by micelles and followed γ-radiation induced polymerization and crosslinking. The resultant PAM-DVB-Li hydrogel electrolyte possesses excellent mechanical properties with 5627 ± 241% stretchability and high ionic conductivity of 53 ± 3 mS cm-1. By in situ polymerization of conducting polyaniline (PANI) on the PAM-DVB-Li hydrogel electrolyte, a novel all-in-one supercapacitor, PAM-DVB-Li/PANI, with highly integrated structure is prepared further. Benefiting from the excellent properties of hydrogel electrolyte and the all-in-one structure, the device exhibits a high specific capacitance of 469 mF cm-2 at 0.5 mA cm-2, good cyclic stability, safety, and deformation damage resistance. More importantly, the device demonstrates a superior tensile resistance (working normally under no more than 300% strain, capacitance stability in 1000 cycles of 1000% stretching and 10 cycles of 3000% stretching) far beyond that of other all-in-one supercapacitors. This work proposes a novel strategy to construct tensile-resistant all-in-one flexible supercapacitors that can be used as an energy storage device for stretchable electronic devices.
Understanding the charge/discharge mechanism of batteries plays an important role in the development of high-performance systems, but extremely complicated reactions are involved. Because these complex phenomena are also bottlenecks for the establishment of all-solid-state batteries (ASSB), we conducted multi-scale analysis using combined multi-measurement techniques, to directly observe charge/discharge reactions at hierarchical scales for the oxide-type ASSB using Na as the carrier cation. In particular, all of measurement techniques are applied to cross-section ASSB in the same cell, to complementarily evaluate the elemental distributions and structural changes. From Operando scanning electron microscopy–energy-dispersive X-ray spectroscopy, the Na concentration in the electrode layers changes on the micrometer scale under charge/discharge reactions in the first cycle. Furthermore, Operando Raman spectroscopy reveal changes in the bonding states at the atomic scale in the active material, including changes in reversible structural changes. After cycling the ASSB, the elemental distributions are clearly observed along with the particle shapes and can reveal the Na migration mechanism at the nanometer scale, by time-of-flight secondary ion mass spectrometry. Therefore, this study can provide a fundamental and comprehensive understanding of the charge/discharge mechanism by observing reaction processes at multiple scales.
Aqueous batteries with metal anodes exhibit robust anodic capacities, but their energy densities are low because of the limited potential stabilities of aqueous electrolyte solutions. Current metal options, such as Zn and Al, pose a dilemma: Zn lacks a sufficiently low redox potential, whereas Al tends to be strongly oxidized in aqueous environments. Our investigation introduces a novel rechargeable aqueous battery system based on Mn as the anode. We examine the effects of anions, electrolyte concentration, and diverse cathode chemistries. Notably, the ClO4-based electrolyte solution exhibits improved deposition and dissolution efficiencies. Although stainless steel (SS 316 L) and Ni are stable current collectors for cathodes, they display limitations as anodes. However, using Ti as the anode resulted in increased Mn deposition and dissolution efficiencies. Moreover, we evaluate this system using various cathode materials, including Mn-intercalation-based inorganic (Ag0.33V2O5) and organic (perylenetetracarboxylic dianhydride) cathodes and an anion-intercalation-chemistry (coronene)-based cathode. These configurations yield markedly higher output potentials compared to those of Zn metal batteries, highlighting the potential for an augmented energy density when using an Mn anode. This study outlines a systematic approach for use in optimizing metal anodes in Mn metal batteries, unlocking novel prospects for Mn-based batteries with diverse cathode chemistries.
The growing demand for flexible, lightweight, and highly processable electronic devices makes high-functionality conducting polymers such as poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT:PSS) an attractive alternative to conventional inorganic materials for various applications including thermoelectrics. However, considerable improvements are necessary to make conducting polymers a commercially viable choice for thermoelectric applications. This study explores nanopatterning as an effective and unique strategy for enhancing polymer functionality to optimize thermoelectric parameters, such as electrical conductivity, Seebeck coefficient, and thermal conductivity. Introducing nanopatterning into thermoelectric polymers is challenging due to intricate technical hurdles and the necessity for individually manipulating the interdependent thermoelectric parameters. Here, array nanopatterns with different pattern spacings are imposed on free-standing PEDOT:PSS films using direct electron beam irradiation, thereby achieving selective control of electrical and thermal transport in PEDOT:PSS. Electron beam irradiation transformed PEDOT:PSS from a highly ordered quinoid to an amorphous benzoid structure. Optimized pattern spacing resulted in a remarkable 70% reduction in thermal conductivity and a 60% increase in thermoelectric figure of merit compared to non-patterned PEDOT:PSS. The proposed nanopatterning methodology demonstrates a skillful approach to precisely manipulate the thermoelectric parameters, thereby improving the thermoelectric performance of conducting polymers, and promising utilization in cutting-edge electronic applications.
Self-assembled monolayers (SAMs) are widely used as hole transport materials in inverted perovskite solar cells, offering low parasitic absorption and suitability for semitransparent and tandem solar cells. While SAMs have shown to be promising in small-area devices (≤1 cm2), their application in larger areas has been limited by a lack of knowledge regarding alternative deposition methods beyond the common spin-coating approach. Here, we compare spin-coating and upscalable methods such as thermal evaporation and spray-coating for [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), one of the most common carbazole-based SAMs. The impact of these deposition methods on the device performance is investigated, revealing that the spray-coating technique yields higher device performance. Furthermore, our work provides guidelines for the deposition of SAM materials for the fabrication of perovskite solar modules. In addition, we provide an extensive characterization of 2PACz films focusing on thermal evaporation and spray-coating methods, which allow for thicker 2PACz deposition. It is found that the optimal 2PACz deposition conditions corresponding to the highest device performances do not always correlate with the monolayer characteristics.
Achieving high-performance aqueous zinc-ion batteries requires addressing the challenges associated with the stability of zinc metal anodes, particularly the formation of inhomogeneous zinc dendrites during cycling and unstable surface electrochemistry. This study introduces a practical method for scattering untreated bulk hexagonal boron nitride (h-BN) particles onto the zinc anode surface. During cycling, stabilized zinc fills the interstices of scattered h-BN, resulting in a more favorable (002) orientation. Consequently, zinc dendrite formation is effectively suppressed, leading to improved electrochemical stability. The zinc with scattered h-BN in a symmetric cell configuration maintains stability 10 times longer than the bare zinc symmetric cell, lasting 500 hours. Furthermore, in a full cell configuration with α-MnO2 cathode, increased H+ ion activity can effectively alter the major redox kinetics of cycling due to the presence of scattered h-BN on the zinc anode. This shift in H+ ion activity lowers the overall redox potential, resulting in a discharge capacity retention of 96.1% for 300 cycles at a charge/discharge rate of 0.5 A g-1. This study highlights the crucial role of surface modification, and the innovative use of bulk h-BN provides a practical and effective solution for improving the performance and stability.
Water electrolysis using renewable electricity is a promising strategy for high-purity hydrogen production. To realize the practical application of water electrolysis, an electrocatalyst with high redox properties and low cost is essential for enhancing the sluggish oxygen evolution reaction. Herein, we fabricated Fe-doped nickel oxalate (Fe-NiC2O4) directly grown on nickel (Ni) foam as an efficient electrocatalyst for the alkaline oxygen evolution reaction using a facile one-step hydrothermal method. Fe-NiC2O4 served as a precursor for obtaining highly active Fe-doped Ni oxyhydroxide (Fe-NiOOH) via in situ electrochemical oxidation. Consequently, 0.75Fe-NiOOH was demonstrated to be the optimal electrocatalyst, exhibiting outstanding oxygen evolution reaction activity with a low overpotential of 220 mV at a current density of 100 mA cm-2 and a Tafel slope of 20.5 mV dec-1. Furthermore, Fe-NiOOH maintained its oxygen evolution reaction activity without performance decay during long-term electrochemical measurements, owing to the phase transformation from nickel oxyhydroxide (NiOOH) to γ-NiOOH (gamma nickel oxyhydroxide). These performances significantly surpass those of recently reported transition-metal-based electrocatalysts.
This study presents a novel Li metal host material with a unique hollow nano-spherical structure that incorporates Ag nano-seeds into a graphitic carbon nitride (g-C3N4) shell layer, referred to as g-C3N4@Ag hollow spheres. The g-C3N4@Ag spheres provide a managed internal site for Li metal encapsulation and promote stable Li plating. The g-C3N4 spheres are uniformly coated using polydopamine, which has an adhesive nature, to enhance lithium plating/stripping stability. The strategic presence of Ag nano-seeds eliminates the nucleation barrier, properly directing Li growth within the hollow spheres. This design facilitates highly reversible and consistent lithium deposition, offering a promising direction for the production of high-performance lithium metal anodes. These well-designed g-C3N4@Ag hollow spheres ensure stable Li plating/stripping kinetics over more than 500 cycles with a high coulombic efficiency of over 97%. Furthermore, a full cell made using LiNi0.90Co0.07Mn0.03O2 and Li-g-C3N4@Ag host electrodes demonstrated highly competitive performance over 200 cycles, providing a guide for the implementation of this technology in advanced lithium metal batteries.
This paper demonstrates the strategic molecular design of functional polymer monoliths comprised of mesoporous fibers with stimuli-responsive Joule-heating properties for the rapid and efficient recovery of viscous fuel oil from water. The mesoporous fibers were composed of carefully selected monomers, which spontaneously entangled with each other to form a spongy monolith in a one-pot synthesis process. The subsequent addition of polypyrrole nanoparticles to the polymer produced superwettable intertwined fibers with strain-responsive conductivity, allowing the monolith to be used as a compressible, fibrous, and porous adsorbent with a high-flux separation capability and a tunable electrical heating effect. This adsorbent was demonstrated to successfully separate different types of low-viscosity oil from water in a continuous, highly efficient process. It also induced a rapid increase in the temperature during the recovery of marine fuel oil (MFO 380), with a minimal compression of 3% under an external voltage. The proposed adsorbent can thus be used for the effective recovery of various fuel oils and improved further by incorporating other synergistic components for various water-treatment systems.
The surface reconstruction behavior of transition metal phosphides precursors is considered as an important method to prepare efficient oxygen evolution catalysts, but there are still significant challenges in guiding catalyst design at the atomic scale. Here, the CoP nanowire with excellent water splitting performance and stability is used as a catalytic model to study the reconstruction process. Obvious double redox signals and valence evolution behavior of the Co site are observed, corresponding to Co2+/Co3+ and Co3+/Co4+ caused by auto-oxidation process. Importantly, the in situ Raman spectrum exhibits the vibration signal of Co–OH in the non-Faradaic potential interval for oxygen evolution reaction, which is considered the initial step in reconstruction process. Density functional theory and ab initio molecular dynamics are used to elucidate this process at the atomic scale: First, OH- exhibits a lower adsorption energy barrier and proton desorption energy barrier at the configuration surface, which proposes the formation of a single oxygen (–O) group. Under a higher –O group coverage, the Co–P bond is destroyed along with the POx groups. Subsequently, lower P vacancy formation energy confirm that the Ni-CoP configuration can fast transform into a highly active phase. Based on the optimized reconstruction behavior and rate-limiting barrier, the Ni-CoP nanowire exhibit an excellent overpotential of 1.59 V at 10 mA cm-2 for overall water splitting, which demonstrates low degradation (2.62%) during the 100 mA cm-2 for 100 h. This work provide systematic insights into the atomic-level reconstruction mechanism of transition metal phosphides, which benefit further design of water splitting catalysts.
Li/Mn-rich layered oxide (LMR) cathode active materials offer remarkably high specific discharge capacity (>250 mAh g-1) from both cationic and anionic redox. The latter necessitates harsh charging conditions to high cathode potentials (>4.5 V vs Li|Li+), which is accompanied by lattice oxygen release, phase transformation, voltage fade, and transition metal (TM) dissolution. In cells with graphite anode, TM dissolution is particularly detrimental as it initiates electrode crosstalk. Lithium difluorophosphate (LiDFP) is known for its pivotal role in suppressing electrode crosstalk through TM scavenging. In LMR ‖ graphite cells charged to an upper cutoff voltage (UCV) of 4.5 V, effective TM scavenging effects of LiDFP are observed. In contrast, for an UCV of 4.7 V, the scavenging effects are limited due to more severe TM dissolution compared an UCV of 4.5 V. Given the saturation in solubility of the TM scavenging agents, which are LiDFP decomposition products, e.g., PO43- and PO3F2-, higher concentrations of the LiDFP as “precursor” cannot enhance the amount of scavenging species, they rather start to precipitate and damage the anode.
Lithium metal batteries are the most promising next-generation energy storage technologies due to their high energy density. However, their practical application is impeded by serious interfacial side reactions and uncontrolled dendrite growth of lithium metal anode. Herein, copper 2,4,5-trifluorophenylacetate is designed and explored to stabilize lithium metal anode by in-situ constructing a dense and mixed-conductive interfacial protective layer. The formed passivated layer not only significantly inhibits interfacial side reactions by avoiding direct contact between lithium metal anode and electrolyte but also effectively suppresses lithium dendrite growth due to the unique inorganic-rich compositions and mixed-conductive properties. As a result, the copper 2,4,5-trifluorophenylacetate-treated lithium metal anodes show greatly improved cycle stability under both high current density and high areal deposition capacity. Notably, the assembled liquid symmetrical cells with copper 2,4,5-trifluorophenylacetate-treated lithium metal anodes can stably work for more than 3000, 5000, and 4800 h at 1.0 mA cm-2–1.0 mAh cm-2, 2.0 mA cm-2–5.0 mAh cm-2, and 10 mA cm-2–5.0 mAh cm-2, respectively. Furthermore, the assembled liquid full cell with a high LiFePO4 loading (∼16.9 mg cm-2) shows a significantly enhanced cycle life of 250 cycles with stable Coulombic efficiencies (>99.1%). Moreover, the assembled all-solid-state lithium metal battery with a high LiNi0.6Co0.2Mn0.2O2 loading (∼5.0 mg cm-2) also exhibits improved cycle stability. These findings underline that the copper 2,4,5-trifluorophenylacetate-treated lithium metal anodes show great promise for high-performance lithium metal batteries.
The development of lithium-ion batteries with high-energy densities is substantially hampered by the graphite anode’s low theoretical capacity (372 mAh g-1). There is an urgent need to explore novel anode materials for lithium-ion batteries. Silicon (Si), the second-largest element outside of Earth, has an exceptionally high specific capacity (3579 mAh g-1), regarded as an excellent choice for the anode material in high-capacity lithium-ion batteries. However, it is low intrinsic conductivity and volume amplification during service status, prevented it from developing further. These difficulties can be successfully overcome by incorporating carbon into pure Si systems to form a composite anode and constructing a buffer structure. This review looks at the diffusion mechanism, various silicon-based anode material configurations (including sandwich, core-shell, yolk-shell, and other 3D mesh/porous structures), as well as the appropriate binders and electrolytes. Finally, a summary and viewpoints are offered on the characteristics and structural layout of various structures, metal/non-metal doping, and the compatibility and application of various binders and electrolytes for silicon-based anodes. This review aims to provide valuable insights into the research and development of silicon-based carbon anodes for high-performance lithium-ion batteries, as well as their integration with binders and electrolyte.
Aqueous zinc-ion batteries encounter impediments on their trajectory towards commercialization, primarily due to challenges such as dendritic growth, hydrogen evolution reaction. Throughout recent decades of investigation, electrolyte modulation by using function additives is widely considered as a facile and efficient way to prolong the Zn anode lifespan. Herein, N-(2-hydroxypropyl)ethylenediamine is employed as an additive to attach onto the Zn surface with a substantial adsorption energy with (002) facet. The as-formed in-situ solid-electrolyte interphase layer effectively mitigates hydrogen evolution reaction by constructing a lean-water internal Helmholtz layer. Additionally, N-(2-hydroxypropyl)ethylenediamine establishes a coordination complex with Zn2+, thereby modulating the solvation structure and enhancing the mobility of Zn2+. As expected, the Zn-symmetrical cell with N-(2-hydroxypropyl)ethylenediamine additive demonstrated successful cycling exceeding 1500 h under 1 mA cm-2 for 0.5 mAh cm-2. Furthermore, the Zn//δ-MnO2 battery maintains a capacity of approximately 130 mAh g-1 after 800 cycles at 1 A g-1, with a Coulombic efficiency surpassing 98%. This work presents a streamlined approach for realizing aqueous zinc-ion batteries with extended service life.
Carbon fibers (CFs) are widely used in cutting-edge and civilian fields due to their excellent comprehensive properties such as high strength and high modulus, superior corrosion and friction resistances, excellent thermal stability, light weight, and high electrical conductivity. However, their natural ultra-black appearance is difficult to meet the aesthetic needs of today’s civilian sector and the need for optical stealth in the military field. In addition, conventional coloring methods are difficult to effectively adhere to CF surfaces due to high crystallinity and highly inert surface caused by their graphite-like structure. In this work, inspired by the nacre structural color of pearls, colored CFs with 1D photonic crystal structure are prepared by cyclically depositing amorphous (Al2O3 + TiO2) layers on the surface of carbon CFs through atomic layer deposition (ALD). The obtained CFs exhibit brilliant colors and excellent environmental durability in extreme environments. Moreover, the colored CFs also exhibit high EMI shielding effectiveness (45 dB) and optical stealth properties, which can be used in emerging optical devices and electromagnetic and optical stealth equipment.
Hydrophobic nanofiber composite membranes comprising polyimide and metal–organic frameworks are developed for desalination via direct contact membrane distillation (DCMD). Our study demonstrates the synthesis of hydrophobic polyimides with trifluoromethyl groups, along with superhydrophobic UiO-66 (hMOF) prepared by phenylsilane modification on the metal-oxo nodes. These components are then combined to create nanofiber membranes with improved hydrophobicity, ensuring long-term stability while preserving a high water flux. Integration of hMOF into the polymer matrix further increases membrane hydrophobic properties and provides additional pathways for vapor transport during MD. The resulting nanofiber composite membranes containing 20 wt% of hMOFs (PI-1-hMOF-20) were able to desalinate hypersaline feed solution of up to 17 wt% NaCl solution, conditions that are beyond the capability of reverse osmosis systems. These membranes demonstrated a water flux of 68.1 kg m-2 h-1 with a rejection rate of 99.98% for a simulated seawater solution of 3.5 wt% NaCl at 70 °C, while maintaining consistent desalination performance for 250 h.
This study demonstrates the fabrication of mesoporous tungsten trioxide (WO3)-decorated flexible polyimide (PI) electrodes for the highly sensitive detection of catechol (CC) and hydroquinone (HQ), two environmental pollutants. Organic–inorganic composite dots are formed on flexible PI electrodes using evaporation-induced self-assembly (EISA) and electrospray methods. The EISA process is induced by a temperature gradient during electrospray, and the heated substrate partially decomposes the organic parts etched by O2 plasma, creating mesoporous structures. Differential pulse voltammetry and cyclic voltammetry demonstrate a linear correlation between analyte concentration and the electrochemical response. Computational studies support the spontaneous adsorption of CC and HQ molecules on model WO3 surfaces. The proposed sensor shows high sensitivity, a wide linear range, and a low detection limit for both individual and simultaneous determination of CC and HQ. Real sample analysis on river water confirms practical applicability. The WO3-decorated PI electrode presents an efficient and reliable approach for detecting these pollutants, contributing to environmental safety measures.
With the pressing concern of the climate change, hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel-based economy. In this case, the role of membrane-based separation cannot be neglected since, compared with other conventional process, membrane-based process is more effective and consumes less energy. Regarding this, metal-based membranes, particularly palladium, are usually employed for hydrogen separation because of its high selectivity. However, with the advancement of various microporous materials, the status quo of the metal-based membranes could be challenged since, compared with the metal-based membranes, they could offer better hydrogen separation performance and could also be cheaper to be produced. In this article, the advancement of membranes fabricated from five main microporous materials, namely silica-based membranes, zeolite membranes, carbon-based membranes, metal organic frameworks/covalent organic frameworks (MOF/COF) membranes and microporous polymeric membranes, for hydrogen separation from light gases are extensively discussed. Their performances are then summarized to give further insights regarding the pathway that should be taken to direct the research direction in the future.
The intricate sulfur redox chemistry involves multiple electron transfers and complicated phase changes. Catalysts have been previously explored to overcome the kinetic barrier in lithium–sulfur batteries (LSBs). This work contributes to closing the knowledge gap and examines electrocatalysis for enhancing LSB kinetics. With a strong chemical affinity for polysulfides, the electrocatalyst enables efficient adsorption and accelerated electron transfer reactions. Resulting cells with catalyzed cathodes exhibit improved rate capability and excellent stability over 500 cycles with 91.9% capacity retention at C/3. In addition, cells were shown to perform at high rates up to 2C and at high sulfur loadings up to 6 mg cm-2. Various electrochemical, spectroscopic, and microscopic analyses provide insights into the mechanism for retaining high activity, coulombic efficiency, and capacity. This work delves into crucial processes identifying pivotal reaction steps during the cycling process at commercially relevant areal capacities and rates.
Nanofiltration (NF) membranes with exceptional ion selectivity and permeability are needed for the recovery of lithium from waste lithium-ion batteries. Herein, inspired by the homogeneous microchannels in the skeletal structure of glass sponges, an innovative biomimetic sponge-like sub-nanostructured NF membrane was designed using an alkali-induced MXene (AMXene)-ethyl formate (EF)-induced bulk/interfacial diffusion decoupling strategy to simultaneously improve Li+/Co2+ selectivity and membrane permeability. The Li+/Co2+ separation factor (SLi,Co = 24) of the engineered membrane was improved by an order of magnitude compared to that of an NF270 membrane (SLi,Co = 2). The selectivity of Mg2+/Na+ (BNaCl/BMgCl2 = 286) and SO42-/Cl- (BNaCl/BNaSO4 = 941) increased by 3 ∼ 12 times, and the permeability (25.8 L m-2 h-1 bar-1) remained at a desirable level, beyond the current upper bound of the other cutting-edge membranes. The superior performance was attributed to the limited release of amine in bulk phase and the boosted interfacial diffusion by reducing interfacial energy barrier during the interfacial polymerization reaction, which were realized via the synergetic effects of AMXene and EF. This approach yielded a biomimetic sponge-like sub-nanostructured NF membrane with controlled homogeneous pore radii (0.202 nm) and a thickness as small as 16.08 nm, which led to high ion selectivity and permeability. The engineered membrane was capable of efficient separation and recovery of Li+/metal ions.
Alpha-voltaic cell is a type of micro nuclear battery that provides several decades of reliable power in the nanowatt to microwatt range, supplying for special applications where traditional chemical batteries or solar cells are difficult to operate. However, the power conversion efficiency of the alpha-voltaic cells reported are still far behind the theoretical limit, making the development of alpha-voltaic cell challenging. Developing advanced semiconductor transducers with higher efficiency in converting the energy of alpha particles into electric energy is proving to be necessary for realizing high-power conversion efficiency. Herein, we propose an alpha-voltaic cell based on SiC PIN transducer that includes a sensitive region with an area of 1 cm2, a width of 51.2 µm, and a charge collection efficiency of 95.6% at 0 V bias. We find that optimizing the unintentional doping concentration and crystal quality of the SiC epitaxial layer can significantly increase the absorption and utilization of the energy of alpha particles, resulting in a 2.4-fold enhancement in power conversion efficiency compared with that of the previous study. Electrical properties of the SiC alpha-voltaic cell are measured using an He-ion accelerator as the equivalent α-radioisotopes, with the best power conversion efficiency of 2.10% and maximum output power density of 406.66 nW cm-2 is obtained. Our research makes a big leap in SiC alpha-voltaic cell, bridging the gap between micro nuclear batteries and practical applications in micro-electromechanical systems, micro aerial vehicles, and tiny satellites.
High-temperature performance of energy storage dielectric polymers is desired for many electronics and electrical applications, but the trade-off between energy density and temperature stability remains fundamentally challenging. Here, we report a general material design strategy to enhance energy storage performance at high temperatures by crosslinking a polar polymer and a high glass-transition temperature polymer as a crosslinked binary blend. Such crosslinked binary polymers display a temperature-insensitive and high energy density behavior of about 6.2 ∼ 8.5 J cm-3 up to 110 °C, showing a significant enhancement in thermal resistant properties and consequently outperforming most of the other ferroelectric polymers. Further microstructural investigations reveal that the improved thermal stability stems from the confinement effect on conformational motion of the crosslinking network, which is evidenced by the increased rigid amorphous fraction and steady intermolecular distance of amorphous regions from temperature-dependent X-ray diffraction results. Our findings provide a general and straightforward strategy to attain temperature-stable, high-energy-density polymer-based dielectrics for energy storage capacitors.
Cobalt pentlandite (Co9S8) is a promising non-precious catalyst due to its superior oxygen reduction reaction activity and excellent stability. However, its oxygen reduction reaction catalytic activity has traditionally been limited to the four-electron pathway because of strong *OOH intermediate adsorption. In this study, we synthesized electron-deficient Co9S8 nanocrystals with an increased number of Co3+ states compared to conventional Co9S8. This was achieved by incorporating a high density of surface ligands in small-sized Co9S8 nanocrystals, which enabled the transition of the electrochemical reduction pathway from four-electron oxygen reduction reaction to two-electron oxygen reduction reaction by decreasing *OOH adsorption strength. As a result, the Co3+-enriched Co9S8 nanocrystals exhibited a high onset potential of 0.64 V (vs RHE) for two-electron oxygen reduction reaction, achieving H2O2 selectivity of 70–80% over the potential range from 0.05 to 0.6 V. Additionally, these nanocrystals demonstrated a stable H2O2 electrosynthesis at a rate of 459.12 mmol g-1 h-1 with a H2O2 Faradaic efficiency over 90% under alkaline conditions. This study provides insights into nanoscale catalyst design for modulating electrochemical reactions.
Metal dichalcogenide-based 2D materials, gained considerable attention recently as a hydrogen evolution reaction (HER) electrocatalyst. In this work, we synthesized MoSe2-based electrocatalyst via hydrothermal route with varying phase contents (1T/2H) and respective HER performances were evaluated under the acidic media (0.5 M H2SO4), where best HER performance was obtained from the sample consisting of mixed 1T/2H phases, which was directly grown on a carbon paper (167 mV at 10 mA cm-2) Furthermore, HER performance of electrocatalyst was further improved by in-situ electrodeposition of Pt nanoparticles (0.15 wt%) on the MoSe2 surface, which lead to significant enhancement in the HER performances (133 mV at 10 mA cm-2). Finally, we conducted density functional theory calculations to reveal the origin of such enhanced performances when the mixed 1T/2H phases were present, where phase boundary region (1T/2H heterojunction) act as a low energy pathway for H2 adsorption and desorption via electron accumulation effect. Moreover, presence of the Pt nanoparticles tunes the electronic states of the MoSe2 based catalyst, resulting in the enhanced HER activity at heterointerface of 1T/2H MoSe2 while facilitating the hydrogen adsorption and desorption process providing a low energy pathway for HER. These results provide new insight on atomic level understanding of the MoSe2 based catalyst for HER application.