Efficient Electrode Research Articles

Efficient Gate-Tunable Hot-Carrier Photocurrent from Perovskite Multiple Quantum Wells.

Hot-carrier relaxation above the bandgap results in significant energy losses, making the extraction of hot carriers a critical challenge for efficient hot-carrier photocurrent generation in devices. In this study, we observe long-lived hot carriers in the metal-halide perovskite multiple quantum wells, (BA)2(MA)n-1PbnI3n+1 (n = 3), and demonstrate effective hot-hole photocurrent generation using 2DMoS₂ as an extraction layer. A high external quantum efficiency of short-circuit hot-carrier photocurrent of up to 35.4% is achieved. Further enhancement in photocurrent efficiency and open-circuit photovoltage is achieved when a gate electric field is applied, resulting in an external quantum efficiency of up to 61.9%. Evidence of hot-hole extraction is validated through operando transient reflection measurements on the working devices, with studies that depend on wavelength, carrier density, and gate voltage. DFT calculations on the heterostructure devices under different bias voltages further elucidate the mechanism of hot-hole extraction enhancement. These findings underscore the potential of perovskite multiple quantum wells as long-lived hot-carrier generators and highlight the role of 2D transition metal dichalcogenide semiconductors as efficient hot-carrier extraction electrodes for low-power optoelectronics.

Dynamic Redeposition Over Bidirectional Amorphous NiFe-Oxides toward Surface Self-Healing for the Alkaline Oxygen Evolution Reaction.

The NiFe-oxy/hydroxides (NiFeOxHy) have emerged as promising candidates for alkaline oxygen evolution reaction (OER) but suffer from irreversible metal dissolution to pose a great challenge to long-term stability. Here, a self-supported electrode of NiFeOxHy/FeNiOx/SS-A (substrate-etched stainless steel, SS-A; interlayer-amorphous Fe3Ni1Ox oxide; catalytic layer-amorphous Ni3Fe1OxHy) is fabricated and presents rare self-healing property of surface cracks, as well excellent activity and stability. It is found that crack repair is driven by the redeposition of dissolved Fe and Ni ions from the amorphous interlayer involved in the OER process because no similar behavior is observed in Fe-free and crystalline interlayer-supported NiFeOxHy. Moreover, the repair performance is dependent on current density and electrolysis time, with 71% of surface cracks being repaired after 72h operated on an industrial level of 500mA cm-2. It needs to be emphasized that the irreversible dissolution of Fe and Ni from the catalytic layer of NiFeOxHy still occurs but is effectively suppressed. It is demonstrated that the construction of an amorphous FeNiOx oxide interlayer in self-supported electrodes plays an important role in improving the stability and is expected to open up an opportunity for the design and develop highly efficient and durable alkaline OER catalytic electrodes.

Enhanced electrocatalytic performance and exceptional durability facilitate the effective degradation of m-dinitrobenzene wastewaters utilizing a novel SS/PbO2-Y2O3-SiC electrode

The intrinsic toxicity of m-dinitrobenzene (m-DNB) to human health and the environment has made dealing with m-DNB pollution a major concern. Herein, a novel hydrophobic anodic electrode SS/PbO2-Y2O3-SiC doped with Y and SiC was constructed via a simple electrodeposition strategy for efficient degradation of m-DNB. With a dense-uniform structure and hydrophobic surface, such SS/PbO2-Y2O3-SiC electrode exhibits obviously lower activation energy (8.17kJmol−1) and charge transfer resistance (1.15 Ω cm2), higher electrochemical active area (46.14 cm2) and stability (359 d), in comparison to SS/PbO2. The m-DNB removal efficiency of the as-prepared SS/PbO2-Y2O3-SiC anode was significantly increased to 96.4% in 180minutes, and the degradation reaction-order was determined to be 0.9559, which was in accordance with the quasi-first-order reaction kinetics. These are the possible degradation pathways of m-DNB under the action of both cathodic and anodic reactions, according to the GC-MS results. The -NO2 group of m-DNB was first reduced to the -NH2 group at the cathode surface, and then the m-phenylenediamine generated at the cathode was sequentially oxidised by the hydroxyl radicals generated from the anodic electrochemical process, resulting in the generation of H2O and CO2 at the anode surface. Additionally, the Assessment Software Tool (TEST) shows that the SS/PbO2-Y2O3-SiC anode can effectively reduce the risk and harm of m-DNB to the overall environment. This study offers novel perspectives on the development of a highly efficient PbO2 electrode for the degradation of m-DNB pollutants.

Dual-function efficient hydrogen evolution reaction electrocatalyst and electrode material for supercapacitors based on ternary composite FeS2/Fe2O3/MoS2 nanostructures

Hydrogen is a promising and environment-friendly energy source that can be produced in a highly efficient manner through water electrolysis. This process requires the use of effective electrocatalysts to facilitate the hydrogen evolution reaction (HER). In this study, the synthesis, characterization, and electrochemical performance of FeS2, Fe2O3, a binary composite of FeS2 and Fe2O3 (FeS2/Fe2O3), and a ternary composite of FeS2, Fe2O3, and MoS2 (FeS2/Fe2O3/MoS2) are investigated. The materials were prepared using a hydrothermal technique and analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–Vis) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and electrochemical assessments. The ternary composite demonstrated improved HER performance, with the FeS2/Fe2O3/MoS2 hybrid exhibiting the highest electrochemically active surface area ECSA (27.79 μF/cm2), and lowest charge transfer resistance Rct (288 Ω), overpotential (96 mV vs. SHE at 10 mA/cm2) and Tafel slope (72 mV/decade), indicating the superior performance of the ternary composite in facilitating the HER. These results indicate that the combination of MoS2 with FeS2 and Fe2O3 greatly enhances the catalytic activity, making the ternary composite a highly attractive option for effective water-splitting applications. In addition, the hybrid composite exhibited outstanding supercapacitor performance, with a specific capacitance of 171.42 F/g at a current density of 1 A/g. These results indicate that FeS2/Fe2O3/MoS2 can function as a highly effective electrocatalyst for the HER and is a superior material for supercapacitors.

Cellulose Nanofiber-Supported Electrochemical Percolation of Capacitive Nanomaterials with 0D, 1D, and 2D Structures.

Cellulose nanofiber (CNF) represents a promising support material to strengthen the mechanical property of free-standing supercapacitor electrodes comprised of conducting nanomaterials. Although efforts have been focused on improving the performance of the CNF-supported electrode, the percolation of capacitive nanomaterials within the insulating CNF matrix, and its correlation with the nanomaterial's dimensionality are still underexplored. In this work, membrane supercapacitor electrodes are fabricated by incorporating CNF with 0D, 1D, and 2D capacitive nanocarbons respectively to study the impact of their dimensionality. It is found that the percolation pathway of the nanocarbons is dependent on their dimensionality. By introducing a new definition termed as electrochemical percolation threshold, the threshold weight percentages to realize effective electrochemical percolation are determined to be 60.0, 14.3, and 66.7% for 0D, 1D, and 2D nanocarbons, respectively. Increasing the weight percentage beyond the threshold typically results in improved electrochemical percolation but reduced mechanical strength, and both trends are dependent on the nanocarbon's dimensionality. The results provide guidance to design efficient and robust CNF-supported supercapacitor electrodes by controlling the dimensionality and density of the active material. The insights regarding the electrochemical percolation threshold can be applied to other energy-storage nanomaterials to advance the development of insulator-supported supercapacitors.

Can 3D-printed flow electrode gaskets replace CNC-milled graphite current collectors in flow capacitive deionization?

As billions of people suffer from water scarcity, finding sustainable water resources is imperative. Flow capacitive deionization (FCDI) is a highly promising desalination process that can produce clean water from saline streams such as brackish and seawater. Conventional FCDI systems employ Computerised Numerical Control (CNC)-milled graphite plates that serve as current collectors and flow electrode channels. However, they have drawbacks such as high manufacturing costs, waste generation, and the difficulty of producing complex geometries required for efficient flow electrode mixing. Here, we successfully demonstrate that 3D-printed flow electrode gaskets, made of non-conductive polyethylene terephthalate glycol (PET-G) or a carbon black-infused conductive polylactic acid (PLA), are viable alternatives to traditional graphite plates. In specific cases, the desalination and energy efficiency in FCDI cells with 3D-printed conductive gaskets were even 25 % and 10 % higher, respectively, compared to traditional CNC-milled current collectors. The transition to 3D printing offers notable benefits, such as the competence to fabricate complex designs that enhance internal mixing and charge percolation. This innovation represents a change of paradigm in the way FCDI cells should be designed and manufactured, using additive manufacturing, which represents an efficient, scalable, and cost-effective substitute for the conventional approach, contributing therefore for the advancement of FCDI desalination technology.

An Efficient Tri-Conductive Electrode for Ethane Direct Electrochemical Dehydrogenation on Proton Ceramic Electrolysis Cells.

The preparation of ethylene from ethane, a main component of shale gas, has become an important process of the petrochemical industry, using ethane steam cracking at high temperatures (>900 °C), which is a highly energy intensive industry. Here, direct dehydrogenation of ethane is engineered electrochemically to produce ethylene and hydrogen in a proton-conducting electrolysis cell, achieving over 50% ethane conversion and 90.42% ethylene selectivity at 700 °C. On the basis of constructing NiCu bimetallic alloy nano-catalyst on the surface of perovskite Sr3Fe2O7, Hafnium (Hf)element is doped in the bulk phase to improve proton conductivity, establish triple conductivity, and achieve efficient directional conversion of ethane. The carbon dioxide reduction reaction at the cathode is further coupled, resulting in a higher conversion of ethane on the anode side and the production of syngas on the cathode side. This electrochemical reaction process provides a choice for the clean production of high value-added small molecule chemical products.

Facile hydrothermal synthesis of Cu doped MoS2 nanoparticles for enhanced dye-sensitized solar cell performance

This study presents a facile, scalable, and cost-effective hydrothermal method for synthesizing Cu doped MoS2 nanoparticles as efficient counter electrodes for dye-sensitized solar cells (DSSCs). MoS2 nanoparticles were doped with Cu at 5 and 10 mol% concentrations. The structural, morphological, and optoelectronic properties of the synthesized MoS2:Cu nanoparticles were systematically characterized using a suite of microscopic and spectroscopic techniques. DSSCs were fabricated using pure MoS2, MoS2@Cu 5 mol%, and MoS2@Cu 10 mol% as counter electrodes, and their photovoltaic performance was evaluated. The DSSC with pure MoS2 counter electrode exhibited a short-circuit current density (Jsc) of 11.02 mA/cm2, an open-circuit voltage (Voc) of 0.70 V, a fill factor (FF) of 70 %, and a power conversion efficiency (PCE) of 5.39 %. The MoS2@Cu 5 mol% electrode demonstrated enhanced performance with Jsc = 13.04 mA/cm2, Voc = 0.71 V, FF = 72 %, and PCE = 6.55 %. Notably, the MoS2@Cu 10 mol% electrode exhibited superior performance, achieving Jsc = 14.09 mA/cm2, Voc = 0.73 V, FF = 81 %, and a remarkable PCE of 8.12 %. This significant enhancement in photovoltaic parameters is attributed to the improved photovoltaic performance and charge transport properties of the Cu doped MoS2 nanoparticles. Our findings demonstrate the potential of Cu-doped MoS2 as an effective and low-cost alternative to conventional counter electrode materials in DSSCs, paving the way for further optimization and scalable production of high-efficiency solar cells.

Self-Organized Integrated Electrocatalyst on Oxygen Conversion for Highly Durable Zinc-Air Batteries.

Efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are key for clean energy applications such as rechargeable metal-air batteries. Highly efficient bifunctional electrocatalysts have been the focus of great attention by scientists. Here, an innovative and continuous growth method is established to fabricate integrated Janus structure Co3O4/CoNGDY catalyst, which can work for bifunctional oxygen catalytic conversion, achieving highly durable zinc-air batteries. Embedded in the hydrangea-shaped N-doped graphdiyne (NGDY), the Co3O4/CoNGDY is self-organized by CoNGDY at the NGDY contact sites and Co3O4 at the upper part, in which Co3O4 works as OER catalyst and CoNGDY acts as ORR catalyst. Due to the incomplete charge transfer within integrated structure, NGDY reduces the d-band center of the Co sites, so the adsorption strength of intermediates is balanced, and the catalytic activity for ORR/OER is increased. The Co3O4/CoNGDY can serve as an efficient air electrode of rechargeable zinc-air batteries. The rechargeable Co3O4/CoNGDY-based aqueous zinc-air batteries demonstrate excellent performance with a high specific capacity of 746.8 mAh g-1 and an extremely long lifetime of more than 5000 hours. The recoverable modularized cylindrical Co3O4/CoNGDY-based solid-state zinc-air batteries with a power density of up to 167.6 mW cm-2 can be achieved.

Facile and ecofriendly green synthesis of Co3O4/MgO-SiO2 composites towards efficient asymmetric supercapacitor and oxygen evolution reaction applications.

The development of low-cost, eco-friendly, and earth-friendly electrode materials for energy storage and conversion applications is a highly desirable but challenging task for strengthening the existing renewable energy systems. As part of this study, orange peel extract was utilized to synthesize a magnesium oxide-silicon dioxide hybrid substrate system (MgO-SiO2) for coating cobalt oxide nanostructures (Co3O4) via hydrothermal methods. A variety of MgO-SiO2 compositions were used to produce Co3O4 nanostructures. The purpose of using MgO-SiO2 substrates was to increase the porosity of the final hybrid material and enhance its compatibility with the electrode material. This study investigated the morphology, chemical composition, optical properties, and functional group properties. In hybrid materials, the shape structure is inherited from nanoparticles with uniform size distributions that are well compacted. A relative decrease in the optical band was observed for Co3O4 when deposited onto an MgO-SiO2 substrate. An improvement in the electrochemical properties of Co3O4/MgO-SiO2 composites was observed during the measurements of supercapacitors and oxygen evolution reaction (OER) in alkaline solutions. The Co3O4/MgO-SiO2 composite prepared on 0.4 g of the MgO-SiO2 substrate (sample 2) demonstrated excellent specific capacitance, high energy density, and recycling stability for 40 000 galvanic charge-discharge cycles. The assembled asymmetric supercapacitor (ASC) device demonstrated a specific capacitance of 243.94 F g-1 at a current density of 2 A g-1. Co3O4/MgO-SiO2 composites were found to be highly active towards the OER in 1 M KOH aqueous solution with an overpotential of 340 mV at 10 mA cm-2 and a Tafel slope of 88 mV dc-1. It was found that the stability and durability were highly satisfactory. Based on the use of orange peel extract, a roadmap was developed for the synthesis of porous hybrid substrates for the development of efficient electrode materials for energy storage and conversion.

Uncovering the Potential of Two-Dimensional SrRuO3 as anode material in Li, Na, Mg, Ca, K, and Zn ion Batteries: First-Principles investigations of structural, electronic and electrochemical properties

The development of robust and efficient electrode materials is priority area in the battery research to realize large capacity, high stability, and hasty carrier mobility. In this study, first principles investigations are carried out to evaluate potential of SrRuO3 as anode material for use in rechargeable monovalent and multivalent ion batteries including Li ion batteries (LIBs), Na ion batteries (NIBs), Mg ion batteries (MIBs), Ca ion batteries (CIBs), potassium ion batteries (KIBs) and Zn ion batteries (ZIBs). The optimal anodic properties of the material are systematically examined, focusing on its structural properties, electronic characteristics, diffusion barriers, storage capabilities, and studies on adsorption sites. The layered structure of the material appeared to accommodate several atoms of different metal during charge / discharge cycles. The exothermic interactions of Li, Na, Mg, Ca, K, and Zn with the host SrRuO3 show their appropriateness for the intercalation process in the batteries. The storage capacity for the LIB, NIB, MIB, CIB, KIB, and ZIB is calculated as 1211 mAhg−1, 990 mAhg−1, 2201 mAhg−1, 1100 mAhg−1, 770 mAhg−1 and 1516 mAhg−1, respectively. The respective values of open circuit voltage are determined as 0.48 V, 0.94 V, 1.3 V, 1.15 V, 0.7 V and 1.17 V for LIB, NIB, KIB, MIB, CIB and ZIB. The minimal diffusion barrier calculated for active ion migration of Li (0.38 eV), Na (0.18 eV), K (0.35 eV), Mg (0.81 eV), Ca (0.86 eV) and Zn (0.92 eV) in the host material indicate excellent transport character for the batteries. The low values of volume expansion (%) of the host material calculated as 1.29 %, 30 %, 25 %, 5 %, 12 % and 7 % for LIB, MIB, KIB, NIB, CIB and ZIB respectively, point to good cyclic stability. Furthermore, non-equilibrium Greens function approach was employed to examine electron transport characteristics involved in solid electrolyte interphase (SEI) formation. The findings of the study predict the excellent anodic performance of SrRuO3 for multivalent ion batteries.

Bilayer Boost to UV Assisted Supercapacitors: Enhanced Performance with Transparent TiO2/MoO3 Heterojunction Electrode

AbstractPhoto‐assisted supercapacitor is a promising smart device component for achieving both energy conversion and storage. The photo‐assisted functionality in a supercapacitor is realized through the choice of photo responsive electrode material under suitable illumination conditions. The well‐known electrochemically active electrode materials are wide band gap semiconductors which absorb strongly in UV light. However, most of the prior studies on photo‐assisted supercapacitors used visible light. Herein, we present a transparent TiO2/MoO3 bi‐layer heterojunction made by simple solution process as an efficient electrode for photo‐assisted supercapacitors under UV light illumination. The electrochemical performance of the electrode is significantly enhanced even with a less intense (0.05 mW/cm2) UV light, compared to dark as well as the single layer electrode under same illumination condition. The highest areal capacitance of 63.25 mF/cm2 at 0.1 mA/cm2 is achieved, that surpasses most of the recent relevant reports. The synergetic effect of UV illumination and the built‐in potential at the type II heterojunction interface encourages ion insertion and better collection of the photo‐generated carriers. The unique bi‐layer design also leads to better rate capability features. Thus, the work presents a new prospect for the development of transparent energy storage devices to be used in future smart technologies.

Dual-synergistic effect of medium-entropy metal sulfoselenide nanoparticles toward efficient overall seawater splitting

Developing efficient and durable electrodes for overall water splitting (OWS) in seawater electrolytes is a major challenge. Herein, we synthesized highly active and stable Fe1.2(CoNi)1.8S3Se3 medium-entropy metal sulfoselenide (MESSe) nanoparticles for the electrodes. The Fe1.2(CoNi)1.8S3Se3 MESSe electrode exhibited excellent electrocatalytic performance in alkaline simulated seawater, with a η100 value of 156 mV for the hydrogen evolution reaction and 262 mV for the oxygen evolution reaction. Compared to Fe1.2(CoNi)1.8S6 sulfide and Fe1.2(CoNi)1.8Se6 selenide, the electronic structure of Fe1.2(CoNi)1.8S3Se3 MESSe positively modulates the adsorption/desorption process of *H/*OH intermediate and significantly reduces the free energy of the rate-determining step, thereby accelerating the reaction kinetics of both hydrogen/oxygen evolution reactions. The performance of OWS is significantly enhanced by utilizing the prepared electrode, enabling it to achieve 100 mA cm−2 with only 1.77 V in alkaline simulated seawater. Furthermore, the durability of the electrode is maintained at this high current density in alkaline simulated seawater, alkaline seawater as well as seawater electrolyte. This work will lay the foundation for the development of innovative medium-entropy metal sulfoselenides, promoting their application in a wide range of electrochemical energy systems operating under extreme conditions.

Time and cost efficient post-synthesized core-shell NiCo-MOFs electrode for solid-state supercapacitors

Designing electrode materials with a core-shell structure proves to be an efficient strategy for achieving high conductivity and surface area in supercapacitors (SCs), facilitating improved charge transfer and faradaic reactions. Leveraging the advantages of core-shell architectures for SCs, we synthesized binder-free Co-MOFs (CMFS) and core-shell NiCo-MOFs (NCMFS) electrodes through a facile chemical process on stainless steel substrates. Morphological analysis reveals interconnected leaf-like structures for CMFS and a porous sheet-like morphology for NCMFS electrodes. Further, the structural, morphological, and compositional analysis reveals the existence of a core-shell NiCo structure in the NCMFS electrode. This unique architecture significantly enhances electrochemical properties, as evidenced by a specific capacitance of 1016 F/g, substantially surpassing that of CMFS (557 F/g) at 2 A/g. Impressively, both materials demonstrate excellent cycling stability, a critical parameter for real-time SCs applications. Furthermore, symmetric solid-state SCs NCMFS//NCMFS device exhibited an energy density of 8.19 Wh/kg, a power density of 2117 W/kg at 4 A/g, and a 67% retention rate over 3000th cycles. The study highlights the importance of core-shell structures in enhancing the performance of SCs. Moreover, it demonstrates the efficacy of post-synthesis methodologies in surpassing traditional hydrothermal and solvothermal approaches for producing advanced energy storage devices. This approach offers significant advantages in terms of time efficiency and cost-effectiveness.

Self-supported bifunctional porous Ni–Fe-based electrode via one-step reduction method for efficient water splitting

Efficient, inexpensive, and robust bifunctional electrodes are crucial for water splitting. Herein, the three-dimensional hierarchical porous nickel-iron (Ni–Fe)- based monolith is directly fabricated through a one-step reduction approach of their oxide precursors under a hydrogen atmosphere. The Ni–Fe alloy as the active material of water splitting is simultaneously formed during the reduction process and water is the only by-product, which is facile and environmentally friendly. The effects of the reduction temperatures and the Fe contents on the microstructures and composition of the obtained Ni–Fe samples are systematically investigated. The optimized Ni–Fe-based monolith is used as a self-supporting electrode for oxygen evolution reaction, its electro-oxidized derivatives show a low overpotential of 217 mV at 10 mA cm−2 and an ultralow Tafel slope of 31 mV dec−1 in 1 M KOH. Furthermore, the electrolyzer consisting of the bifunctional electrode demonstrates outstanding performance of 1.49 V at 10 mA cm−2 and exceptional long-term stability over 1000 h at 50 mA cm−2, surpassing the majority of alkaline electrolyzers utilizing Ni–Fe-based electrodes.

Novel NiCoMn MOFs/Ag citrate nanocomposites for high-performance asymmetric supercapacitor applications

Addressing the challenges posed by the global energy crisis, this research article explores the pivotal role of novel NiCoMn MOFs/Ag Citrate Nanocomposites in advancing high-performance asymmetric supercapacitor applications. This study delves into the synthesis of an efficient supercapacitor electrode material using a nanocomposite, denoted as MAx (where x = 1-3), combining NiCoMn metal-organic frameworks (MOFs, represented as M) with Ag-Citrate (notated as A). This synthesis employs an ultrasonication-assisted solvothermal approach. The XRD and SEM analyses authenticate the presence of anticipated phases and elements, revealing a seamless integration of the two components. Electrochemical assessments suggest that introducing Ag-citrate significantly augments the charge storage prowess of the nanocomposites. Specifically, the MA1 nanocomposite showcases a remarkable specific capacity of 762 C/g at 0.5 Ag−1, marking enhancements of 83 % and 10 % compared to pure Ag-citrate and unaltered MOFs, respectively. Furthermore, the asymmetric supercapacitor device based on this nanocomposite delivers optimal metrics: a specific capacity of 291.6 C/g at 2 Ag−1, an energy density of 61 Whkg−1, a power density of 1500 Wkg−1, a Coulombic efficiency of 98.5 %, and an enduring stability of 101 % over 4000 cycles. This exploration accentuates the significant promise of NiCoMn MOFs/Ag-Citrate nanocomposites as efficient, economical, and durable supercapacitors for a spectrum of energy storage needs.

High-efficiency electrocatalytic hydrogen generation under harsh acidic condition by commercially viable Pt nanocluster-decorated non-polar faceted GaN nanowires

Electrochemical water splitting is vital for green hydrogen production and clean energy. This study introduces a novel approach: platinum nanoclusters (Pt NCs) decorated GaN nanowires (GNWs) on p++-Si substrates to enhance hydrogen generation efficiency. Highly-crystalline GNWs synthesized via commercial metal-organic chemical vapor deposition provide a scalable platform for hydrogen evolution. To address the cost limitations of Pt-based electrocatalysts, we developed a method for loading ultralow Pt NCs via photoelectrochemical deposition. Investigations underscore the Pt–Ga sites' crucial role in promoting efficient H2 production. The Pt NCs/GNWs/p++-Si electrode achieved −10 mA/cm2 current density at +50 mV vs. the RHE and sustained −20 mA/cm2 for 90 h under harsh acidic conditions at room temperature and atmospheric pressure with nearly 100% retention. This study offers insights into efficient and stable electrodes for electrochemical H2 generation.

Covalent Organic Frameworks (COFs): A New Class of Materials for Multivalent Metal‐Ion Energy Storage Systems

AbstractThe rise of electronic societies is driving a surge in the demand for energy storage solutions, particularly in the realm of renewable energy technologies like batteries, which rely heavily on efficient electrode materials and separators. As an answer to this necessity, Covalent Organic Frameworks (COFs) are emerging and a highly intriguing class of materials, garnering increased attention in recent years for their extensive properties and possible applications. This review addresses the remarkable versatility and boundless potential of COFs in scientific fields, mainly focusing on multivalent metal ion batteries (MMIBs), which include AIB (Aluminium‐ion batteries), MIB (Magnesium‐ion battery), CIB (Calcium‐ion battery), and ZIB (Zinc‐ion battery), as both electrode materials and separators across a spectrum of battery technology. Inclusive of their approaches, merits, and reaction mechanisms, this review offers an extensive summary of COFs concerning multivalent ion batteries. By providing a rigorous analysis of COF attributes, electrochemical behaviour, and methodologies, our explanation contributes to a deeper understanding of their potential in advancing battery technology.

Optimizing Sodium Ion Adsorption Through Robust d–d Orbital Modulation for Efficient Capacitive Deionization

AbstractUnraveling the fundamental mechanisms of sodium ion adsorption behavior is crucial for guiding the design of electrode materials and enhancing the performance of capacitive deionization systems. Herein, the optimization of sodium ion adsorption is systematically investigated through the robust d–d orbital interactions within zinc‐doped iron carbide, facilitated by a novel liquid nitrogen quenching treatment. Liquid nitrogen quenching treatment can enhance the coordination number, strengthen d–d orbital interactions, promote electron transfer, and shift the d‐band center of Fe closer to the Fermi level, thereby enhancing sodium ions adsorption energy. Consequently, the obtained electrode material achieves a superior gravimetric adsorption capacity of 121.1 mg g−1 and attractive cyclic durability. The adsorption capacity is highly competitive compared to the vast majority of related research works in the field of capacitive deionization. Furthermore, sodium ion adsorption/desorption mechanisms are substantiated through ex situ techniques, revealing dynamic atomic and electronic structure evolutions under operational conditions. This work demonstrates that optimizing sodium ion adsorption via robust d–d orbital modulation enabled by liquid nitrogen quenching treatment is an effective approach for developing efficient capacitive deionization electrode materials.

Electronic Structure Engineering of RuNi Alloys Decrypts Hydrogen and Hydroxyl Active Site Separation and Enhancement for Efficient Alkaline Hydrogen Evolution.

Rational design of the active sites of hydrolysis dissociation intermediates to weaken their active site competition and toxicity is a key challenge to achieve efficient and stable hydrogen evolution reaction (HER) in ruthenium-containing alloys. Density Functional Theory (DFT) simulations reveal that the transfer of the d-band electrons from Ru to Ni in RuNi alloys results in a Gibbs free energy of -0.12eV for the Ru0.250Ni Fcc-site H*. In addition, the high spin state of the electrons outside the Ru nucleus strengthens the adsorption of OH* on the Ru─Ni bond, which weakens the active-site competition and toxicity successfully. This theoretical prediction is confirmed by electrodeposition of prepared aRuxNi, and the RuNi alloys obtained by Ru atom doping have excellent HER properties. aRu0.250Ni has overpotentials of 38 and 162.4mV at -10 and -100mAcm-2, respectively, and can be stably operated at -100mAcm-2 Dual-electrode system aRu0.250Ni//bRu0Ni demonstrates an ultra-low battery voltage (1.86V @500mAcm-2) and excellent stability (24h@300mAcm-2). This holistic work resolves the mechanism of active site separation and strengthening in RuNi alloys, and provides a new design idea for the preparation of highly efficient alkaline HER electrodes.