Formation Of Heterostructures Research Articles

Unlocking highly stable and reversible in-situ integration of defect-rich 2D vanadium sulfide with Ti3C2Tx MXene heterostructures: Boosting asymmetric supercapacitor performance

To broaden the functionalities of transition metal dichalcogenides and two-dimensional transition metal carbides such as MXenes (Ti3C2Tx-MX), it is necessary to appropriately integrate them with each other to form heterostructures. The integrated heterostructures should maintain functionality through strong covalent interaction and offer excellent electrochemical properties. The requirement for developing appropriately integrated heterostructures is the control of nucleation and growth by governing the reaction kinetics. However, developing heterostructures over MXenes on a large scale is extremely challenging. Herein, we propose an investigation to elucidate the formation of defect-rich conductive heterostructures by in-situ integration of vanadium sulfide (VS2) on the surface of Ti3C2Tx-MX (VS2–Ti3C2Tx-MX) via controlled nucleation and growth in a facile hydrothermal process. The scrutinized binder-free flexible fabric-based VS2–Ti3C2Tx-MX0.25 electrode exhibits an excellent specific capacitance of 750 F g−1 and long-term stability (∼93 % retention after 10000 cycles). Moreover, these defect-rich and interlayer-expanded integrated heterostructures showed exceptional cycling stability and an impressive energy density of 52.08 Wh kg−1 at a power density of 750 W kg−1 when employed as fabric-based asymmetric supercapacitor (ASC) devices with VS2–Ti3C2Tx-MX0.25//Ti3C2Tx-MX configuration. We anticipate that the approach presented in this work will promote the development of various MXene-based heterostructures for manipulating the versatile properties of MXenes and VS2 in energy storage applications.

Unveiling the Potential of Covalent Organic Frameworks for Energy Storage: Developments, Challenges, and Future Prospects

AbstractCovalent organic frameworks (COFs) are porous structures emerging as promising electrode materials due to their high structural diversity, controlled and wide pore network, and amenability to chemical modifications. COFs are solely composed of periodically arranged organic molecules, resulting in lightweight materials. Their inherent properties, such as extended surface area and diverse framework topologies, along with their high proclivity to chemical modification, have positioned COFs as sophisticated materials in the realm of electrochemical energy storage (EES). The modular structure of COFs facilitates the integration of key functions such as redox‐active moieties, fast charge diffusion channels, composite formation with conductive counterparts, and highly porous network for accommodating charged energy carriers, which can significantly enhance their electrochemical performance. However, ascribing intricate porosity and redox‐active functionalities to a single COF structure, while maintaining long‐term electrochemical stability, is challenging. Efforts to overcome these hurdles embrace strategies such as the implementation of reversible linkages for structural flexibility, stimuli‐responsive functionalities, and incorporating chemical groups to promote the formation of COF heterostructures. This review focuses on the recent progress of COFs in EES devices, such as batteries and supercapacitors, through a meticulous exploration of the latest strategies aimed at optimizing COFs as advanced electrodes in future EES technologies.

Noncovalent synthesis of homo and hetero-architectures of supramolecular polymers via secondary nucleation

The synthesis of supramolecular polymers with controlled architecture is a grand challenge in supramolecular chemistry. Although living supramolecular polymerization via primary nucleation has been extensively studied for controlling the supramolecular polymerization of small molecules, the resulting supramolecular polymers have typically exhibited one-dimensional morphology. In this report, we present the synthesis of intriguing supramolecular polymer architectures through a secondary nucleation event, a mechanism well-established in protein aggregation and the crystallization of small molecules. To achieve this, we choose perylene diimide with 2-ethylhexyl chains at the imide position as they are capable of forming dormant monomers in solution. Activating these dormant monomers via mechanical stimuli and hetero-seeding using propoxyethyl perylene diimide seeds, secondary nucleation event takes over, leading to the formation of three-dimensional spherical spherulites and scarf-like supramolecular polymer heterostructures, respectively. Therefore, the results presented in this study propose a simple molecular design for synthesizing well-defined supramolecular polymer architectures via secondary nucleation.

Solid-State Anion Exchange Enabled by Pluggable vdW Assembly for In Situ Halide Manipulation in Perovskite Monocrystalline Film.

The fabrication of perovskite single crystal-based optoelectronics with improved performance is largely hindered by limited processing techniques. Particularly, the local halide composition manipulation, which dominates the bandgap and thus the formation of heterostructures and emission of multiple-wavelength light, is realized via prevalent liquid- or gas-phase anion exchange with the utilization of lithography, while the monocrystalline nature is sacrificed due to polycrystalline transition in exchange with massive defects emerging, impeding carrier separation and transportation. Thus, a damage-free and lithography-free solid-state anion exchange strategy, aiming at in situ halide manipulation in perovskite monocrystalline film, is developed. Typically, CsPbCl3 working as medium to deliver halide is van der Waals (vdW) assembled to specific spots of CsPbBr3, followed by the removal of CsPbCl3 after anion exchange, with the halide composition in contact area modulated and monocrystalline nature of CsPbBr3 preserved. CsPbBr3-CsPbBrxCl3-x monocrystalline heterostructure has been achieved without lithography. Device based on the heterostructure shows apparent rectification behavior and improved photo-response rate. Heterostructure arrays can also be constructed with customized medium crystal. Furthermore, the halide composition can be accurately tuned to enable full coverage of visible spectra. The solid-state exchange enriches the toolbox for processing vulnerable perovskite and paves the way for the integration of monocrystalline perovskite optoelectronics.

Regulating the P-band center of SnS2-SnO2 heterostructure to boost the redox kinetics for high-performance lithium-sulfur battery

Lithium-sulfur batteries (LSBs) are considered a strong contender for the new-generation secondary energy storage system due to their high capacity and energy density. However, the sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LPSs) severely hinder the cycle stability. The robust design of both the separator and cathode exhibit an effective role in restricting the shuttle effect and accelerating redox kinetics through the LPSs trapping and catalyzing effect. In this paper, a CNT-modified tin sulfide and tin oxide (SnS2-SnO2-CNTs) heterostructure was constructed as a multifunctional catalyst to modify both the separator and cathode to achieve high-performance LSBs. The formation of SnS2-SnO2 heterostructure promotes the movement of the P band center of the tin atom to the Fermi level, which realizes the association process of adsorption, capture, and conversion of LPSs, thus effectively suppressing the shuttle effect. The SnS2-SnO2 heterogeneous interface can also reduce the deposition barrier of Li2S, thus greatly promoting the redox kinetics. Together with the improved electron transfer, the resulting LSBs with the robust electrode and separator exhibit superior electrochemical performance with a high initial capacity of 930.2 mAh g−1 at 1 C with a high sulfur loading of 4.3 mg cm−2 and a remarkable capacity of up to 580.3 mAh g−1 at an ultrahigh rate of 7.4 C.

An efficient photo-Fenton In2O3@FeIn2S4 composite catalyst for tetracycline degradation

Photo-Fenton technology has been widely used as an efficient and environmentally friendly method for pollutant degradation. Herein, novel In2O3@FeIn2S4 microflowers are prepared by a two-step hydrothermal method and used as the photo-Fenton catalyst for tetracycline (TC) degradation. Under illumination (λ > 420 nm), the In2O3@FeIn2S4-0.5 (molar mass ratio of FeIn2S4 to In2O3 is 0.5) shows a higher removal efficiency of TC (98.3 %) in 75 min, than pure In2O3 (60.8 %) and FeIn2S4 (65.8 %). The degradation rate constant of In2O3@FeIn2S4-0.5 for TC is about 5.1 and 3.2 times compared to that of In2O3 and FeIn2S4. In addition, the TC removal efficiency only dropped by 6.7 % after 5 cycles, indicating the superior stability of In2O3@FeIn2S4-0.5. Superoxide radical (∙O2–), hydroxide radical (∙OH), and singlet oxygen (1O2) play a crucial role in TC degradation process, while photogenerated holes (h+) only play a minor role. The improved performance of In2O3@FeIn2S4 photo-Fenton catalyst could be described as the following: the porous In2O3 microflower supporter extends the reactive interface of FeIn2S4; FeIn2S4 effectively enhances optical absorption ability in the visible range; 2D-2D tight interface formed between In2O3 and FeIn2S4 helps to accelerate the charge transfer; the formation of S-scheme heterostructures improves the parting ability of the photoproduced carriers.

Tailored Two‐Dimensional Transition Metal Dichalcogenides for Water Electrolysis: Doping, Defect, Phase, and Heterostructure

AbstractThe demand for hydrogen production technology to replace fossil fuels and address the global climate crisis has become one of the most urgent tasks in the modern era. Among the promising breakthroughs, electrochemical water splitting using renewable energy sources offers a path to green hydrogen production that is both feasible and economically viable. However, the current state‐of‐the‐art catalysts for the water‐splitting reaction predominantly rely on scarce and costly noble metals, posing a significant challenge to the mass production of green hydrogen. In this context, two‐dimensional transition metal dichalcogenides (2D TMDs) have emerged as compelling candidates to replace noble metals, owing to their impressive reactivity and cost‐effectiveness. These TMD‐based electrocatalysts demonstrate exceptional reactivity at their active edge sites, while the basal planes remain catalytically inert. Several tailored strategies can activate these basal planes by modifying the chemical bonding nature and electronic band structure of the constituent atoms, thus enhancing the overall reactivity of TMDs. This review summarizes recent advancements in the modulation methodologies of 2D TMDs to enhance their water‐splitting reactivity. We highlight various chemical modification strategies, including heteroatom doping, defect‐engineering, and heterostructure formation, and provide insights into future research directions for the development of advanced 2D TMD‐based water‐splitting catalysts.

Synergistic Sb2S3-NiS2 heterostructure: A robust electrocatalyst for electrochemical sensing of Hg (II), As (III) ions and carbendazim fungicide

We developed a novel modified electrode based on Sb2S3-NiS2 heterostructure for the electrochemical detection of carbendazim, mercury (Hg2+), and arsenic (As3+). XRD, FESEM, HRTEM, and XPS characterization techniques were employed to confirm the formation of Sb2S3-NiS2 heterostructures. In comparison to other electrodes, the Sb2S3-NiS2 modified electrode has a strong electrocatalytic performance towards carbendazim, Hg2+, and As3+ detection. The Sb2S3-NiS2 nanocomposite's superior electrocatalytic activity is ascribed to its high conductivity, charge capacitance, synergistic effect, substantial number of active sites, and metal trap centres. Electrochemical studies such as cyclic voltammetry, LSV, and DPV depict excellent sensing capacity of Sb2S3-NiS2 for carbendazim, Hg2+, and As3+ with an ultralow detection limit calculated as 0.42 nM, 8.3 nM, and 92 nM, respectively. This is much below the upper limit established by the World Health Organization and the US Environmental Protection Agency. The chronoamperometry response and reusability up to weeks suggest excellent and superior stability. Furthermore, the modified electrode successfully detected carbendazim in real samples of apple and tomato juices and Hg2+ ions in the water of the Dal Lake. As far as we know, this is the first report on the Sb2S3-NiS2 heterostructure's electrocatalytic capability. Hopefully, this study will provide new insight into the future fabrication and development of novel electrocatalyst materials.

Interface optoelectrical dynamic in 2D perovskite/InSe heterostructure

Van der Waals (vdW) heterostructure composed of two-dimensional (2D) materials and 2D perovskite has shown excellent optoelectrical properties recently, while the interfacial coupling is less investigated. Here, van der Waals InSe/(C4H9NH3)2(CH3NH3)Pb2I7 heterostructure is fabricated and systemically investigated by photoluminescence (PL) spectroscopy. An optical broadband emission is generated due to the formation of heterostructure. The first principle calculation and variable PL spectra suggest the dynamic generation of defects such as iodine vacancy and charge states. Electron–phonon coupling of the 2D perovskite is weakened from −127 meV to −90 meV in the heterostructure. The band offset causes the built-in electrical field, which strengthens the optoelectrical response of heterostructure devices. The results deepen the understanding of the interfacial optoelectrical dynamic of 2D perovskite-related vdW heterostructure and help develop superior optoelectrical vdW heterostructure devices.

Harnessing In2O3 as an electron aggregator to assist BiOBr nanosheets for enhanced photocatalytic CO2 reduction activity

The advancement of catalysts featuring high carrier separation efficiency enhances photocatalytic reduction performance. This study employed a simple hydrothermal method to anchor In2O3 nanoparticles onto the surface of two-dimensional BiOBr nanosheets, constructing a type-II heterostructure that improves the photocatalytic reduction capability. The composites of 0D/2D In2O3/BiOBr underwent XPS, TPR, and MS characterization, validating the formation of a type-II heterostructure. In2O3 functioned as an electron-aggregating active site that extracted photogenerated electrons from the surface of BiOBr. As a result, the efficiency of charge separation is markedly increased. The results of the CO2 reduction test indicate that In2O3-modified BiOBr exhibits superior photocatalytic activity compared to pure BiOBr, with 2 % In2O3/BiOBr exhibiting the highest reduction performance. The CO yield achieved was 9.81 µmol·g−1·h−1, which is 5.33 times higher than that of pure BiOBr and 42.65 times higher than that of pure In2O3. These findings offer future potential for the application of In2O3 as an electron-accumulating material to enable the photocatalytic reduction of CO2.

Rapid thermal annealing treatment on WO3 thin films for energy efficient smart windows

Electrochromic devices (ECDs) based on tungsten trioxide (WO3) have garnered significant attention in the areas of smart windows, dynamic display, low-power displays, and in other advanced sectors. The electrochromic property of WO3 is primarily influenced by both electron conduction and ion diffusion processes. This research investigates on the influence of rapid thermal annealing (RTA) on the electrochromic performance of RF sputtered tungsten oxide thin films, which relies on ion diffusion process. RTA treated film showed a mixture of amorphous and crystalline (monoclinic), heterostructure phase. Structural, compositional, electrical, optical, morphological, and electrochromic studies were carried out using various techniques. Based on the electrochromic analysis, WO3 thin films, RTA treated at 300°C showed higher diffusion coefficient with larger optical modulation (ΔT) of 80 % due the formation of heterostructure with more oxygen vacancies. We hope that this research could propose the possibility for developing high-performance electrochromic smart windows.

Fabrication of CoFe-LDH nanosheets@CoP nanowires hierarchical heterostructure with enhanced bifunctional electrocatalytic activity for alkaline water splitting

Exploring high active, low cost and stable electrocatalysts to replace noble precious metals has always been the major challenge in overall water splitting applications. Herein, CoFe-layered double hydroxide/Cobalt phosphide heterostructures on nickel foam (CoFe-LDH@CoP/NF) have been synthesized by using hydrothermal, chemical vapor deposition (CVD) and electrodeposition methods. The CoFe-LDH nanosheet is uniformly deposited on the surface of CoP nanowires to create the heterostructure. The formation of heterostructure increases active surface area, accelerates charge transfer velocity, optimizes the kinetics of reaction, thereby significantly improves electrocatalytic activity of the materials. The CoFe-LDH@CoP/NF attains 10 mA cm−2 with a low overpotential of 238 mV for OER and only 63 mV for HER. The catalyst provides the current density of 10 mA cm−2 throughout the overall water splitting by only requiring a low potential of 1.54 V. The CoFe-LDH@CoP/NF as an ideal electrocatalyst provides new ideas for developing efficient non-noble metal-based overall water splitting catalysts.

S-scheme CoFe2O4/g-C3N4 nanocomposite with high photocatalytic activity and antibacterial capability under visible light irradiation

Photocatalysts with bactericidal capabilities are taken much more into consideration due to the water disinfection aside from water purification Therefore, a magnetically separable CoFe2O4/g-C3N4 nanocomposite has been synthesized via a simple in-situ chemical method, and its performance in degrading methylene blue (MB), methyl orange (MO), and phenol has been investigated. Multiple characterization techniques were conducted to confirm the successful synthesis of cobalt ferrite (CF), graphitic carbon nitride (CN), and cobalt ferrite/graphitic carbon nitride (CF/CN) nanocomposites. The microscopy images indicated a great reduction in the size of CF nanoparticles in nanocomposites. The magnetic characteristics were studied by a vibrating sample magnetometer (VSM). CF showed a high magnetization value (41.4 emu/g) and by compositing CF with CN, the nanocomposite also showed considerable magnetic properties. Optical properties of the photocatalysts were analyzed and the results denoted that heterostructure formation between CF and CN led to better light absorption, reduction in the band gap energy, and enhancement of charge carriers separation. Among the different synthesized nanocomposites, 400 mg/L of the CF/25 wt% CN nanocomposite showed the best photocatalytic activity in 180 min by degrading 100% of MB. The Mott-Schottky analysis and the results of scavenging experiments divulged the superoxide radicals as the main active species along with proposing a S-scheme mechanism on the degradation pathway for CF/CN nanocomposite. The optimized nanocomposite demonstrated high stability after three cycles by over 98% degradation of MB. Eventually, the antibacterial feature of CF/25CN nanocomposite was assessed against Escherichia coli and Staphylococcus aureus bacteria and resulted in a magnificent performance by reducing 99.9% of both bacteria in 30 min.

Photoelectrothermocatalytic reduction of CO2 to glycol via Cu2S/MoS2-Vs octahedral heterostructure with synergistic mechanism

The defects and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials to enhance catalytic performance. In this study, we report a new MOFs-driven porous Cu2S/MoS2-Vs octahedral semiconductor with heterostructure and photothermal effect. The introduction of sulfur vacancies directly improves the adsorption performance of CO2, and the formation of heterostructure significantly increases the charge transfer rate. The C-penetrating material obtained from MOFs not only acts as an octahedral skeleton support, but also gives photothermal effects under photoelectric conditions. The formation rate of sole C2 products in photoelectrocatalytic CO2 reduction by using Cu2S/MoS2-Vs heterostructure is up to 52 μM·h−1·cm−2 equal to the total electron transfer rate of 541 μM·h−1·cm−2. The carbene mechanism and reaction pathways were proposed and verified by 13CO2 isotopic labelling and operando Fourier transform infrared (FT-IR) spectra. The important intermediates of *CO2−, *CO, *CHO and *CHO-CHO were identified by operando FT-IR spectra. In the comparative experiments, the photothermal electrons are beneficial to C2 products. DFT calculations indicate that the presence of S vacancies (Vs) reduces the energy barrier for product generation.

Zn-assisted low-temperature reconstruction of NiCo heterogeneous catalysts for lithium-oxygen batteries

Developing catalysts with high catalytic activity and durability is an effective strategy for improving the electrochemical performance of lithium-oxygen batteries (LOBs). Metal atom doping and heterostructure construction have shown great potential in catalysis and are expected to be widely used in energy storage. In this study, a Zn-doped NiCo2O4/NiO heterostructured complex catalyst is designed and prepared as a cathode catalyst for LOBs. This metal-doped heterostructured complex catalyst, prepared at a lower annealing temperature, retains the most active sites. Additionally, the three-dimensional hollow structure of the catalyst not only facilitates mass transfer but also provides active sites through doping and heterostructure formation. The Zn-doped NiCo2O4/NiO catalyst exhibits excellent catalytic performance, resulting the generation of a silky Li2O2 discharge product film, and the higher adsorption energy for the intermediate product LiO2 also allows the discharge product to be tightly bound to the catalyst. The improved contact between the discharge products and the catalyst's active sites, along with the increased surface area, enhances charge transport and decomposition properties, leading to good reversibility of the LOB. Consequently, the LOB based on Zn-doped NiCo2O4/NiO heterostructure complex catalyst features high discharge capacity (12160 mAh/g at 200 mA g−1) and excellent durability (353 cycles, ∼1765 h). Furthermore, theoretical calculations show that the Zn-doped complex heterostructures have enhanced reaction kinetics of OER and ORR. This straightforward method of producing metal-doped heterostructured complex catalysts that induce uniform Li2O2 deposition valuable insights for enhancing the performance of LOBs.

Rational design of covalent organic frameworks/NaTaO3 S-scheme heterostructure for enhanced photocatalytic hydrogen evolution

As a typical perovskite material, NaTaO3 has been regarded as a potential catalyst for photocatalytic hydrogen evolution (PHE) process, due to its excellent photoelectric property and superior chemical stability. However, the photocatalytic activity of pure NaTaO3 was largely restricted by its poor visible-light absorption ability and rapid recombination of photogenerated charge carriers. Therefore, a covalently bonded TpBpy covalent organic framework (COF)/NaTaO3 (TpBpy/NaTaO3) heterostructure was designed and synthesized by the post modification strategy with (3-aminopropyl) triethoxysilane (APTES) and the in situ solvothermal process. Benefiting from the enhanced built-in electric field by the interfacial covalent bonds and the formation of S-scheme heterostructure between TpBpy and NaTaO3, which were proved by the Ar+-cluster depth profile and X-ray photoelectron spectroscopy (XPS), as well as density functional theory (DFT) calculation results, both the charge transfer efficiency and the PHE performance of the TpBpy/NaTaO3 composites were significantly improved. Additionally, the composites exhibited an excellent absorption performance in the visible region, which was also beneficial for the photocatalytic process. As expected, the optimal TpBpy/20%NaTaO3 composite achieved a remarkable hydrogen evolution rate of 17.3 mmol·g−1·h−1 (10 mg of catalyst) under simulated sunlight irradiation, which was about 173 and 2.4 times higher than that of pure NaTaO3 and TpBpy, respectively. This work provided a novel strategy for constructing highly effective and stable semiconductor/COFs heterostructures with strong interfacial interaction for photocatalytic hydrogen evolution.

ZnxFe3-xO4–ZnO heterojunction interfaced with poly(L-DOPA) electron transfer mediator layer for enhanced visible light photocatalytic activity

Z-scheme heterojunctions comprising ZnxFe3-xO4@poly(L-DOPA)@ZnO (ZF@PD@ZnO) were synthesized using solvothermal and precipitation techniques. The study aimed to investigate the impact of the poly(L-DOPA) electron transfer mediator on the photocatalytic performance of ZnxFe3-xO4@ZnO (ZF@ZnO) nanocomposites under visible light irradiation. X-ray diffraction (XRD) and HRTEM analysis confirmed the formation of heterostructures, identifying the crystalline phases of both ZnO and zinc ferrite. BFTEM images revealed a polyhedral shape for all samples, with a tendency toward mild agglomeration. The partial inversion of the zinc ferrite cubic spinel structure was evidenced by FT-IR, XPS, and VSM analyses. Zinc ferrite was found to be ferromagnetic, with cation distributions between tetrahedral (A) and octahedral (B) positions as [Zn0.62+Fe0.43+]A[Fe0.42+Fe1.63+]BO4. The samples exhibited notable photocatalytic activity against Rhodamine B, serving as a model contaminant. Furthermore, the stability and reusability of the samples were examined. Additionally, the study elucidated the photocatalytic mechanism produced by the ternary Z-scheme ZF@PD@ZnO, involving spin-polarized charge carriers. Energy band alignment was evaluated by combining ultraviolet photoelectron spectroscopy (UPS) with UV-Vis spectroscopy. The interplay between band alignment and reactive oxygen species (ROS) generation was discussed in correlation with EPR results. Enhanced ROS generation under visible light illumination, observed in the ZF@PD@ZnO nanocomposite, is mainly due to the addition of the conductive poly(L-DOPA) layer, acting as an electron transfer mediator in the Z-scheme heterojunction, ensuring enhanced charge separation.

Growth Processing and Strategies: A Way to Improve the Gas Sensing Performance of Nickel Oxide-Based Devices

The review paper provides a comprehensive analysis of nickel oxide (NiO) as an emerging material in environmental monitoring by surveying recent developments primarily within the last three years and reports the growth processing and strategies employed to enhance NiO sensing performance. It covers synthesis methods for pristine NiO, including vapor-phase, liquid-phase, and solution-processing techniques, highlighting advantages and limitations. The growth mechanisms of NiO nanostructures are explored, with a focus on the most recent research studies. Additionally, different strategies to improve the gas sensing performance of NiO are discussed (i.e., surface functionalization by metallic nanoparticles, heterostructure formation, carbon-based nanomaterials, and conducting polymers). The influence of these strategies on selectivity, sensitivity, response time, and stability of NiO-based sensors is thoroughly examined. Finally, the challenges and future directions that may lead to the successful development of highly efficient NiO-based gas sensors for environmental monitoring are introduced in this review.

Cu2O-based trifunctional catalyst for enhanced alkaline water splitting and hydrazine oxidation: Integrating sulfurization, Co incorporation, and LDH heterostructure

Developing an efficient electrocatalyst capable of working for multiple catalytic reactions in the same pH environment is a challenging task. In this work, we aimed to address this challenge by employing a systematic approach including sulfurization, Co incorporation, and heterostructure formation with layered double hydroxide (LDH) to unveil the potential of Cu2O for driving multiple catalytic reactions. The systematically modified Cu2O-electrocatalyst demonstrated remarkable efficiency in promoting the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and hydrazine oxidation reaction (HzOR). The LDH-modified Cu2O_S_Co_CoFe sample exhibited an outstanding catalytic activity with low overpotentials of 280 mV for HER and 307 mV for OER at 100 mA cm−2 current density. The same sample also exhibited a remarkably reduced potential of only 0.343 V vs. RHE (VRHE) for HzOR at 100 mA cm−2 as compared to that of 1.53 VRHE for OER. Moreover, in a two-electrode setup for overall water splitting, the electrocatalyst achieved a significantly low cell voltage of 1.64 V to attain a current density of 20 mA cm−2 and further reduced to just 0.36 V during HzOR.

Synergy of Mo doping and heterostructures in FeCo2S4@Mo-NiCo LDH/NF as durable and corrosion-resistance bifunctional electrocatalyst towards seawater electrolysis at industrial current density

Electrolysis of seawater to produce hydrogen is a replenished way to utilize sustainable hydrogen energy. However, it remains a challenge to develop electrocatalysts with high chloride corrosion resistance and meet the industrial-required low overpotential at large current density. Here, a heterostructure FeCo2S4@Mo-NiCo LDH/NF (FCS@M-NC LDH/NF) catalyst consisting of Mo-doped NiCo LDH nanosheets on FeCo2S4 nanorods grown on nickel foam is demonstrated as a large-current–density electrocatalyst for seawater electrolysis. The hierarchical structure endows FCS@M-NC LDH/NF with abundant active sites and hydrophilic and aerophobic surfaces, which promotes the adsorption of OH− and accelerates gas-release capabilities during water electrolysis. Moreover, the incorporation of high-valence Mo species and the presence of heterostructures contribute to the outstanding corrosion resistance, selectivity, and activity of FCS@M-NC LDH/NF, which only requires 314 mV (HER) and 307 mV (OER) overpotential to achieve a large current density of 1000 mA cm−2 in alkaline electrolysis of seawater. Impressively, it maintains stable operation for 140 h at a current density of 500 mA cm−2 without the production of hypochlorite. Furthermore, density functional theory calculations demonstrate that Mo doping and formation of heterostructures decrease the adsorption energy barrier for intermediate on FCS@M-NC LDH/NF, which promotes electrocatalytic activity. The robust electronic interaction between FCS and M-NC LDH/NF promotes the redistribution of charges on the interface, boosting electrical conductivity and charge transfer in the FCS@M-NC LDH/NF. This study offers a mild way to create a bifunctional electrocatalyst with exceptional corrosion resistance and stability in industrial high-alkaline natural seawater electrolysis.