氧空位和磷掺杂协同增强铁钴基材料电解水催化性能

为了研发高效、稳定的电解水催化剂,我们以氧空位和磷掺杂为基础,通过原位浸泡生长和两步热处理的方法,在泡沫铁上合成具有氧空位和磷掺杂的纳米花结构作为析氢反应(HER)和析氧反应(OER)双功能电催化剂。CoFe₂O₄已被报道为一种很有前途的OER和氧还原反应(ORR)电催化剂,然而CoFe₂O₄在HER中表现出电导率差、电催化反应慢的特性。CoFe₂O₄中氧空位(Ov)的形成可以有效调控催化剂表面的电子结构,有助于产生更多的缺陷和空位,从而提高OER的活性。随后,引入磷原子填充在空位中,制备的P-Ov-CoFe₂O₄/IF在碱性电催化测试中展现出优异的HER和OER性能,在10 mA·cm^-2电流密度下HER和OER过电位仅为54和191 mV,Tafel斜率分别为57和54 mV·dec^-1,并具有良好的循环稳定性。     

Integrating NiCo Alloys with Their Oxides as Efficient Bifunctional Cathode Catalysts for Rechargeable Zinc–Air Batteries

The lack of high‐efficient, low‐cost, and durable bifunctional electrocatalysts that act simultaneously for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is currently one of the major obstacles to commercializing the electrical rechargeability of zinc–air batteries. A nanocomposite CoO‐NiO‐NiCo bifunctional electrocatalyst supported by nitrogen‐doped multiwall carbon nanotubes (NCNT/CoO‐NiO‐NiCo) exhibits excellent activity and stability for the ORR/OER in alkaline media. More importantly, real air cathodes made from the bifunctional NCNT/CoO‐NiO‐NiCo catalysts further demonstrated superior performance to state‐of‐the‐art Pt/C or Pt/C+IrO₂ catalysts in primary and rechargeable zinc–air batteries.     

MOF‐Derived Hollow CoS Decorated with CeOx Nanoparticles for Boosting Oxygen Evolution Reaction Electrocatalysis

Transition‐metal sulfides (TMSs) have emerged as important candidates for oxygen evolution reaction (OER) electrocatalysts. Now a hybrid nanostructure has been decorated with CeO_x nanoparticles on the surface of ZIF‐67‐derived hollow CoS through in situ generation. Proper control of the amount of CeO_x on the surface of CoS can achieve precise tuning of Co²⁺/Co³⁺ ratio, especially for the induced defects, further boosting the OER activity. Meanwhile, the formation of protective CeO_x thin layer effectively inhibits the corrosion by losing cobalt ion species from the active surface into the solution. It is thus a rare example of a hybrid hetero‐structural electrocatalyst with CeO_x NPs to improve the performance of the hollow TMS nanocage.     

Advanced Bifunctional Oxygen Reduction and Evolution Electrocatalyst Derived from Surface‐Mounted Metal–Organic Frameworks

Metal–organic frameworks (MOFs) and their derivatives are considered as promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which are important for many energy provision technologies, such as electrolyzers, fuel cells and some types of advanced batteries. In this work, a “strain modulation” approach has been applied through the use of surface‐mounted NiFe‐MOFs in order to design an advanced bifunctional ORR/OER electrocatalyst. The material exhibits an excellent OER activity in alkaline media, reaching an industrially relevant current density of 200 mA cm^?2 at an overpotential of only ≈210 mV. It demonstrates operational long‐term stability even at a high current density of 500 mA cm^?2 and exhibits the so far narrowest “overpotential window” ΔE_ORR‐OER of 0.69 V in 0.1 m KOH with a mass loading being two orders of magnitude lower than that of benchmark electrocatalysts.     

Multifunctional Active-Center-Transferable Platinum/Lithium Cobalt Oxide Heterostructured Electrocatalysts towards Superior Water Splitting

Designing cost-effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active-center-transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO₂) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO₂ nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO₂ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Specifically, Pt species are the active centers and LiCoO₂ acts as the co-catalyst for HER, whereas the active center transfers to LiCoO₂ and Pt turns into the co-catalyst for OER. The unique architecture of Pt/LiCoO₂ heterostructure provides abundant interfaces with favorable electronic structure and coordination environment towards optimal adsorption behavior of reaction intermediates. The 30 % Pt/LiCoO₂ heterostructured electrocatalyst delivers low overpotentials of 61 and 285 mV to achieve 10 mA cm⁻² for HER and OER in alkaline medium, respectively.     

Carbon Dots Integrated NiCo2O4 Hierarchical Nanoneedle Arrays Supported on Ni Foam as Efficient and Stable Electrode for Hydrogen and Oxygen Evolution Reactions

The production of hydrogen and oxygen via water electrolysis has become a sustainable and encouraging pathway for the establishment of new energy sources. Herein, we report the successful growth of hierarchical NiCo₂O₄‐carbon dots (CDs) nanoneedle arrays supported on nickel foam through a simple and environmentally benign hydrothermal self‐assembly technique. The designed material acts as a binder free electrode and shows bifunctional electrocatalytic activity for both hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER) in alkaline medium. An electrocatalyst sample with an optimal loading of CDs (25 mg) requires a low overpotential of 146 mV to achieve a current density of 10 mA/cm² for the HER in an alkaline medium, whereas it requires an overpotential of 390 mV to achieve a current density of 50 mA/cm² for the OER in the same alkaline medium. The excellent electrocatalytic activities of the sample with loading of CD can be ascribed due to the presence of large number of exposed active sites offered by CD/NiCo₂O₄ and the enhanced electron transfer processes occurring as a result of hierarchical structure composed of three‐dimensional nickel foam and the NiCo₂O₄?CDs nanoneedle arrays. Thus, the synthesis method introduced in this present work is a facile and cost‐effective approach for the construction of bifunctional electrocatalysts with high reactivity and excellent durability.     

Multifunctional Active‐Center‐Transferable Platinum/Lithium Cobalt Oxide Heterostructured Electrocatalysts towards Superior Water Splitting

Designing cost‐effective and efficient electrocatalysts plays a pivotal role in advancing the development of electrochemical water splitting for hydrogen generation. Herein, multifunctional active‐center‐transferable heterostructured electrocatalysts, platinum/lithium cobalt oxide (Pt/LiCoO₂) composites with Pt nanoparticles (Pt NPs) anchored on LiCoO₂ nanosheets, are designed towards highly efficient water splitting. In this electrocatalyst system, the active center can be alternatively switched between Pt species and LiCoO₂ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Specifically, Pt species are the active centers and LiCoO₂ acts as the co‐catalyst for HER, whereas the active center transfers to LiCoO₂ and Pt turns into the co‐catalyst for OER. The unique architecture of Pt/LiCoO₂ heterostructure provides abundant interfaces with favorable electronic structure and coordination environment towards optimal adsorption behavior of reaction intermediates. The 30 % Pt/LiCoO₂ heterostructured electrocatalyst delivers low overpotentials of 61 and 285 mV to achieve 10 mA cm^?2 for HER and OER in alkaline medium, respectively.     

Hollow Nanotube Ru/Cu2+1O Supported on Copper Foam as a Bifunctional Catalyst for Overall Water Splitting

Hydrogen energy is considered as one of the ideal clean energies for solving the energy shortage and environmental issues, and developing highly efficient electrocatalysts for overall water splitting to produce hydrogen is still a huge challenge. Herein, for the first time, Ru-doped Cu₂₊₁O vertically arranged nanotube arrays in situ grown on Cu foam (Ru/Cu₂₊₁O NT/CuF) are reported and further investigated for their catalytic properties for overall water splitting. The Ru/Cu₂₊₁O NT/CuF presents ultrahigh catalytic activities for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline conditions, and it exhibits a small overpotential of 32 mV at 10 mA cm⁻² in the HER, and only needs 210 mV overpotential to achieve a current density of 10 mA cm⁻² in the OER. Importantly, the alkaline electrolyzer using Ru/Cu₂₊₁O NT/CuF as a bifunctional electrocatalyst only needs 1.53 V voltage to deliver a current density of 10 mA cm⁻², which is much lower than the benchmark of IrO₂(+)/Pt(−) counterpart (1.64 V at 10 mA cm⁻²). The excellent performance of the Ru/Cu₂₊₁O NT/CuF catalyst is attributed to its high conductive substrate and special Ru-doped nanotube structure, which provides a high electrochemical active surface area and 3D gas diffusion channel.     

A Supramolecular Coordination-Polymer-Derived Electrocatalyst for the Oxygen Evolution Reaction

An iron oxide decorated nickel iron alloy nanoparticle/porous graphene hybrid exhibits high electrocatalytic activity and excellent durability toward oxygen evolution reaction (OER). It displays a low overpotential of 274 mV at 10 mA cm⁻², and low Tafel slope of 37 mV dec⁻¹, showing a superior performance to the state-of-the-art RuO₂ OER electrocatalyst.     

A Bifunctional Hybrid Electrocatalyst for Oxygen Reduction and Evolution: Cobalt Oxide Nanoparticles Strongly Coupled to B,N-Decorated Graphene

The electrocatalyzed oxygen reduction and evolution reactions (ORR and OER, respectively) are the core components of many energy conversion systems, including water splitting, fuel cells, and metal–air batteries. Rational design of highly efficient non-noble materials as bifunctional ORR/OER electrocatalysts is of great importance for large-scale practical applications. A new strongly coupled hybrid material is presented, which comprises CoO_x nanoparticles rich in oxygen vacancies grown on B,N-decorated graphene (CoO_x NPs/BNG) and operates as an efficient bifunctional OER/ORR electrocatalyst. Advanced spectroscopic techniques were used to confirm formation of abundant oxygen vacancies and strong Co−N−C bridging bonds within the CoO_x NPs/BNG hybrid. Surprisingly, the CoO_x NPs/BNG hybrid electrocatalyst is highly efficient for the OER with a low overpotential and Tafel slope, and is active in the ORR with a positive half-wave potential and high limiting current density in alkaline medium.     

Bifunctional Electrocatalyst with 0D/2D Heterostructure for Highly Efficient Hydrogen and Oxygen Generation

A novel MoS₂ quantum dots/CoSe₂ nanosheet (MoS₂ QDs/CoSe₂) hybrid with 0D/2D heterostructure has been developed. The CoSe₂ nanosheets (NSs) enable an excellent oxygen evolution reaction (OER) activity with increasing vacancy configuration on one hand, while the MoS₂ QDs serve as an eminent hydrogen evolution reaction (HER) catalyst on the other. By integrating MoS₂ QDs and CoSe₂ NSs, the hybrid exhibits excellent electrocatalytic performances in HER and OER. The unique 0D/2D hetero‐interface increases the exposed active sites and facilitates electron transfer, thereby boosting the electrocatalytic activity. Relatively low overpotentials of 82 mV and 280 mV are required to drive the current density of 10 mA/cm² for HER and OER, with corresponding Tafel slopes of 69 and 75 mV/dec, respectively. As such, this work provides an efficient yet simple approach to construct bifunctional electrocatalysts with enhanced activity and stability.     

Bio-inspired Design of Bidirectional Oxygen Reduction and Oxygen Evolution Reaction Molecular Electrocatalysts

The proper utilization of renewable energy sources has emerged as a major challenge in our pursuit of a sustainable and carbon-neutral energy landscape. Small molecule activation is a key component for proper utilization of renewable energy resources, where O₂/H₂O redox couple is reckoned to be a potential game changer. In this regard, electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have become the prime interest of catalyst designers. Typically, these ORR and OER electrocatalysts are developed distinctly; however, very soon, the requirement of a bidirectional ORR/OER electrocatalyst becomes obvious for practical applicability and rapid energy transduction purposes. A bidirectional catalyst is defined as a catalyst capable of driving a redox reaction in opposing directions. This review has portrayed the development of enzyme structure-inspired design of molecular bidirectional ORR/OER catalysts. The strategic incorporation of secondary and outer coordination sphere features has significantly enhanced the performance of these catalysts, which can be monitored via the key catalytic parameters. These bifunctional OER/ORR catalysts are vital for metal-air battery and fuel cell applications and appropriately poised to lay the foundation for an efficient, economical, and eco-friendly pathway for sustainable energy usage with the rational assembly of energy converting and storage devices.     

Folded nanosheet-like Co<Subscript>0.85</Subscript>Se array for overall water splitting

Active, stable, and earth-abundant bifunctional electrocatalyst for overall water splitting is pivotal to actualize large-scale water splitting via electrolysis. In this work, the hierarchical folded nanosheet-like Co_0.85Se array on Ni foam is constructed by liquid-phase chemical conversion with cobalt precursor nanorod array. It can serve as an efficient bifunctional electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte, with a current density of 10 mA cm^?2 at overpotential of 232 mV for OER and 129 mV for HER and Tafel slope of 78.9 mV dec^?1 for OER and 95.0 mV dec^?1 for HER, respectively. The two-electrode alkaline water electrolyzer utilizing this folded nanosheet-like Co_0.85Se array as both anode and cathode toward overall water splitting offered a current of 10 mA cm^?2 at a cell voltage of 1.60 V. This work explores an efficient and low-cost electrocatalyst for overall water splitting application in alkaline electrolytes.     

Molybdenum-induced tuning 3d-orbital electron filling degree of CoSe2 for alkaline hydrogen and oxygen evolution reactions

The development of high-performance non-precious metal-based robust bifunctional electrocatalyst for both hydrogen evolution reaction(HER) and oxygen evolution reactions(OER) in alkaline media is essential for the electrochemical overall water splitting technologies. Herein, we demonstrate that the HER/OER performance of Co Se₂ can be significantly enhanced by tuning the 3d-orbital electron filling degree through Mo doping. Both density functional theory(DFT) calculations and experime...     

SrNb0.1Co0.7Fe0.2O3−δ Perovskite as a Next‐Generation Electrocatalyst for Oxygen Evolution in Alkaline Solution

The perovskite SrNb_0.1Co_0.7Fe_0.2O_3?δ (SNCF) is a promising OER electrocatalyst for the oxygen evolution reaction (OER), with remarkable activity and stability in alkaline solutions. This catalyst exhibits a higher intrinsic OER activity, a smaller Tafel slope and better stability than the state‐of‐the‐art precious‐metal IrO₂ catalyst and the well‐known BSCF perovskite. The mass activity and stability are further improved by ball milling. Several factors including the optimized e_g orbital filling, good ionic and charge transfer abilities, as well as high OH^? adsorption and O₂ desorption capabilities possibly contribute to the excellent OER activity.     

Molybdenum‐tungsten Oxide Nanowires Rich in Oxygen Vacancies as An Advanced Electrocatalyst for Hydrogen Evolution

Electrolysis of water is a promising way to produce hydrogen fuel in large scale. The commercialization of this technology requires highly efficient non‐noble metal electrocatalysts to decease the energy input for the hydrogen evolution reaction (HER). In this work, a novel nanowire structured molybdenum‐tungsten bimetallic oxide (CTAB‐D‐W₄MoO₃) is synthesized by a simple hydrothermal method followed with post annealing treatment. The obtained metal oxides feature with enhanced conductivity, rich oxygen vacancies and customized electronic structure. As such, the composite electrocatalyst exhibits excellent electrocatalytic performance for HER in an acidic environment, achieving a large current density of 100 mA cm^?2 at overpotential of only 286 mV and a small Tafel slope of 71.2 mV dec^?1. The excellent electrocatalytic HER performance of CTAB‐D‐W₄MoO₃ is attributed to the unique nanowire structure, rich catalytic active sites and promoted electron transfer rate.     

Manganese-Modulated Cobalt-Based Layered Double Hydroxide Grown on Nickel Foam with 1D–2D–3D Heterostructure for Highly Efficient Oxygen Evolution Reaction and Urea Oxidation Reaction

Hydrogen production by energy-efficient water electrolysis is a green avenue for the development of contemporary society. However, the oxygen evolution reaction (OER) and the urea oxidation reaction (UOR) occurring at the anode are impeded by the sluggish reaction kinetics during the water-splitting process. Consequently, it is promising to develop bifunctional anodic electrocatalysts consisting of nonprecious metals. Herein, a bifunctional CoMn layered double hydroxide (LDH) was grown on nickel foam (NF) with a 1D–2D–3D hierarchical structure for efficient OER and UOR performance in alkaline solution. Owing to the significant synergistic effect of Mn doping and heterostructure engineering, the obtained Co₁Mn₁ LDH/NF exhibits satisfactory OER activity with a low potential of 1.515 V to attain 10 mA cm⁻². Besides, the potential of the Co₁Mn₁ LDH/NF catalyst for UOR at the same current density is only 1.326 V, which is much lower than those of its counterparts and most reported electrocatalysts. An urea electrolytic cell with a Co₁Mn₁ LDH/NF anode and a Pt–C/NF cathode was established, and a low cell voltage of 1.354 V at 10 mA cm⁻² was acquired. The optimized strategy may result in promising candidates for developing a new generation of bifunctional electrocatalysts for clean energy production.     

From a Molecular 2Fe‐2Se Precursor to a Highly Efficient Iron Diselenide Electrocatalyst for Overall Water Splitting

A highly active FeSe₂ electrocatalyst for durable overall water splitting was prepared from a molecular 2Fe‐2Se precursor. The as‐synthesized FeSe₂ was electrophoretically deposited on nickel foam and applied to the oxygen and hydrogen evolution reactions (OER and HER, respectively) in alkaline media. When used as an oxygen‐evolution electrode, a low 245 mV overpotential was achieved at a current density of 10 mA cm⁻², representing outstanding catalytic activity and stability because of Fe(OH)₂/FeOOH active sites formed at the surface of FeSe₂. Remarkably, the system is also favorable for the HER. Moreover, an overall water‐splitting setup was fabricated using a two‐electrode cell, which displayed a low cell voltage and high stability. In summary, the first iron selenide material is reported that can be used as a bifunctional electrocatalyst for the OER and HER, as well as overall water splitting.     

Isostructural NiII Metal–Organic Frameworks (MOFs) for Efficient Electrocatalysis of Oxygen Evolution Reaction and for Gas Sorption Properties

Design and synthesis of stable, active and cost-effective electrocatalyst for water splitting applications is an emerging area of research, given the depletion of fossil fuels. Herein, two isostructural Ni^II redox-active metal–organic frameworks (MOFs) containing flexible tripodal trispyridyl ligand ( L ) and linear dicarboxylates such as terephthalate (TA) and 2-aminoterphthalate (H₂NTA) are studied for their catalytic activity in oxygen evaluation reaction (OER). The 2D-layered MOFs form 3D hydrogen bonded frameworks containing one-dimensional hydrophilic channels that are filled with water molecules. The electrochemical studies reveal that MOFs display an efficient catalytic activity towards oxygen evolution reaction in alkaline conditions with an overpotential as low as 356 mV. Further, these 2D-MOFs exhibit excellent ability to adsorb water vapor (180–230 cc g⁻¹ at 273 K) and CO₂ (33 cc g⁻¹ at 273 K). The presence of hydrophilic functionality in the frameworks was found to significantly enhance the electrocatalytic activity as well as H₂O sorption.     

非贵金属电催化析氧催化剂的最新进展

氢气具有环境友好、含量丰富、高能量密度等特点,是一种可以替代化石能源的绿色环保可再生能源. 电解水是制备氢气最有效途径之一. 但在电解水过程中,动力学过程非常缓慢,过电位较大的阳极析氧半反应严重限制了阴极析氢反应效率. 因此,研究高效、稳定和低成本的催化剂来降低析氧反应的过电位,从而提高析氢反应效率受到了广泛关注. 基于非贵金属催化剂本身特性及其在高浓度OH-条件下具有较高OER催化活性等原因,本文首先简要介绍碱性条件下析氧反应机理及其性能的评价方法,然后重点讨论非贵金属电催化析氧催化剂的最新研究进展. 最后对如何深入研究催化机理、设计高效、双功能及新型非贵金属电催化析氧催化剂进行了展望.