双金属Ni-Co基析氧反应电催化剂研究进展

目的  能源消耗的持续增长和化石燃料燃烧带来的环保和能源安全问题已经引起世界各国的广泛关注。因此,发展清洁能源生产技术已成为世界范围内的主要研究重点。氢能具有无污染、比能密度高、资源丰富等特点,是最具潜力的传统化石燃料替代品之一。电催化分解水被认为是最有希望的制氢方法,但阳极上的析氧反应动力学缓慢,能量转换效率低,是大规模制氢的主要瓶颈。与稀有和昂贵的贵金属催化剂相比,镍-钴（Ni-Co）基电催化剂由于具有可调的电子结构、高导电性和低成本优势,有望在碱性溶液中实现卓越的OER活性和耐久性。 方法  文章总结并讨论了在OER中Ni-Co基电催化剂的最新研究发展。重点讨论了Ni-Co基电催化剂的设计和合成,以及在OER过程中提高其电催化性能的研究策略。 结果  为了代替钌、铱等贵金属催化剂,研究者们对Ni-Co基非贵金属催化剂进行了大量研究。包括氧化物、氢氧化物、合金、氮化物、硫化物、磷化物等在内的多种Ni-Co基催化剂通过化学结构的调控,从阳极角度提高了电催化制氢的活性。但这些催化剂又分别面临不同的缺陷,有待进一步研究克服。 结论  开发具有高OER活性的非贵金属催化剂是降低电解水制氢成本,促进氢能产业发展的重要途径。虽然仍有一些技术问题尚未解决限制了Ni-Co基催化剂替代贵金属催化剂,但作为重要的贵金属催化剂替代品,Ni-Co基催化剂的研究为新型催化剂的开发提供了重要选择。     

质子交换膜燃料电池非贵金属催化剂研究进展

贵金属铂（Pt）基催化剂价格昂贵且易中毒,这是造成质子交换膜燃料电池难以大规模商业化的主要原因,而非贵金属催化剂有望替代Pt基催化剂来解决这一难题。本文综述了最近几年非贵金属催化剂在质子交换膜燃料电池中应用的研究进展,并提出了今后的研究重点和方向。     

限域型贵金属氧还原反应电催化剂研究进展北大核心CSCD

开发高效的氧还原反应电催化剂是实现质子交换膜燃料电池规模化应用的关键技术之一。目前常用的贵金属催化剂成本较高,并且稳定性仍需改善。物理限域是改善催化剂稳定性的有效策略,在不影响贵金属催化剂催化活性的前提下,物理限域层不仅可以抑制催化剂的烧结,还能够减少催化剂在反应过程中的团聚、脱落以及溶解等问题,从而提升催化剂的寿命。本文回顾了近年来用于电催化氧还原反应的限域型贵金属催化剂,主要包括导电聚合物限域、非金属氧化物限域、金属氧化物限域以及碳层限域的贵金属催化剂。根据限域层制备策略不同,重点分析了限域层的孔结构、导电性、致密性、抗腐蚀性与催化剂性能之间的构效关系。着重介绍了实现碳层限域的三种策略,包括“沉积-转化”、“嵌入-转化”以及“一步热解”。分析表明,通过构筑具有丰富孔结构、高导电性及合适厚度的限域层能够在保证活性的同时显著提升催化剂稳定性。最后对全文进行了总结并对当前存在的问题进行了整理,同时对未来限域型催化剂的发展进行了展望。     

原位电解合成Ni-B析氧催化剂及其性能研究

以ITO玻片作为基体,在常温常压下采用原位电沉积法制备了Ni-B析氧催化剂。考察了K2B4O7溶液的浓度、温度以及pH值对催化剂的影响和电极反应的Faradaic效率,并通过循环伏安曲线和Tafel曲线考察了Ni-B催化剂的电化学性能,采用XRD、SEM和EDS等分析技术对催化剂的结构、形貌以及组成进行了表征。实验结果表明:原位电解沉积合成的Ni-B析氧催化剂在电解水过程中表现出较高的析氧活性和稳定性,在1mA/cm2电流密度时的析氧过电位约为0.31V。     

非铂燃料电池催化剂研究进展

燃料电池是利用氢能的理想途径,但燃料电池对于铂催化剂的依赖限制了其发展。该文综述了近年来非铂燃料电池催化剂的研究进展。对于质子交换膜燃料电池,因为阳极需铂量低,相关研究主要集中在阴极催化剂上。对于碱性膜燃料电池,一些非贵金属催化剂在阴极展现出较高的活性,但阳极侧动力学缓慢,因此非铂催化剂的研究在两极均有开展。最后,对非铂燃料电池催化剂当前的研究重点和未来的发展方向进行总结和展望,旨在为非铂燃料电池催化剂的研究和长远发展提供指导和参考。     

单原子催化剂在氢燃料电池阴极氧还原反应中的研究进展

氢燃料电池是一种高效、环境友好以及零碳排放的能量转化技术,然而高成本的贵金属催化剂阻碍了其规模化应用。单原子催化剂因具有高原子利用率、高催化活性和选择性、低成本等优点,对氧分子表现出优异的催化还原性能,在氢燃料电池中具有广阔的应用前景。如何设计合成高效和低成本的单原子催化剂成为该领域的研究热点。重点综述贵金属单原子催化剂和非贵金属单原子催化剂在氢燃料电池阴极氧还原反应中的研究进展,总结提出增强单原子催化剂氧还原性能的调控策略,包括配位结构、局域环境、双原子对、缺陷位点以及暴露活性位点等调控机制,为从原子尺度设计高效氧还原催化剂提供了思路借鉴,并对氢燃料电池氧还原单原子催化剂的发展机遇与挑战进行了展望。     

当前实用和未来发展Pt-非Pt氧还原电催化剂研究进展

燃料电池阴极侧氧还原反应由于其迟缓的动力学,使得贵金属铂成为最为高效的电催化剂,成本高昂,限制燃料电池规模化应用。开发低成本、高性能、可实用氧还原电催化剂尤为重要。基于课题组多年在实用化燃料电池氧还原电催化剂的研究情况,综述面向当前实用和未来发展的铂-非铂电催化剂的研究进展。重点介绍实用化高载量、高活性、高结构稳定性铂基电催化剂合成策略以及在燃料电池膜电极中的性能高效表达,同时阐述非铂碳基催化剂理性设计、可控制备。此外,对该研究方向的发展进行展望,以期加速燃料电池关键材料国产化。     

贵金属比例对燃气发动机三元催化剂性能的影响

以燃气发动机用三元催化剂为研究对象,通过模拟配气的方式,在催化剂小样测试台上进行CH_4、CO、NO_x的起燃性能、水热老化性能及不同空燃比窗口下的性能测试,研究贵金属总质量相同时不同贵金属比例对于三元催化剂性能的影响。研究发现,在相同试验条件下,三元催化剂中含有一定比例Pt对CH_4和NOx的转化效率有一定的促进作用,对于CO转化效率无明显影响;在抗老化性方面,Pt/Pd/Rh型催化剂在CH_4和NO_x的转化效率上较Pd/Rh型催化剂劣化严重,但在NO_x转化效率上劣化较小;Pt能够提升三元催化剂降低NO_x排放能力; Pt/Pd/Rh型催化剂较Pd/Rh型催化剂有着更宽广的反应窗口。     

用于酸性析氧反应研究的原位表征技术

质子交换膜(PEM)水电解的阳极催化剂需要耐受强酸性环境以及析氧反应(OER)条件下的高氧化电位.为了加深对酸性介质中OER过程的理解以开发具有更好稳定性与更高活性的电催化剂,研究和发展原位表征技术显得尤为重要.该综述介绍了几种用于酸性OER研究的原位表征技术,包括:原位X射线光电子能谱技术、原位X射线吸收谱技术、原位X射线衍射/散射技术、原位电化学红外技术、原位电化学拉曼技术、原位电感耦合等离子体-质谱技术、微分电化学质谱/在线电化学质谱技术、电化学石英微晶天平技术.重点讨论了这些技术的原位装置设计以及它们在酸性OER研究领域的具体应用.最后总结了这些技术的特征,并指出用于酸性OER的原位表征技术的发展之有待解决的问题,即新技术的研发与原位技术间的联用、原位装置的改进及时空分辨率的提高.     

过渡金属基催化剂用于氧析出反应的研究进展

由于动力学缓慢,在能源转换和储存过程中,特别是在电解水过程,氧析出反应(OER)是一个关键的限制性反应.目前该领域所面临的主要挑战是探索不含贵金属的催化剂,以促进OER反应过程.由于独特的化学、物理特性和低廉的使用成本,过渡金属基化合物在水的电化学分解过程中的应用得到了广泛关注.本文综述了尖晶石、钙钛矿和层状双金属氢氧化物(LDH)三种过渡金属化合物作为OER电催化剂的最新研究现状和进展,重点介绍了提高OER催化活性和催化剂稳定性的策略以及相应催化剂的催化性能和效果.综合当前文献的研究结果可以发现,OER催化活性的提高主要有两种措施:一是在催化剂中引入更多的催化活性位点,并且保证这些活性位点尽可能暴露在催化剂的表面;二是优化催化剂的导电性能.通过控制尺寸、形态、晶格缺陷、氧空位、相态及化学组成,或者与导电材料相复合,可以在一定程度上满足上述两种要求.最后,对OER电催化剂的未来发展方向进行简要讨论.     

Enhanced oxygen evolution reaction kinetics through biochar-based nickel-iron phosphides nanocages in water electrolysis for hydrogen production

Highly-efficient and stable non-noble metal electrocatalysts for overcoming the sluggish kinetics of oxygen evolution reaction (OER) is urgent for water electrolysis. Biomass-derived biochar has been considered as promising carbon material because of its advantages such as low-cost, renewable, simple preparation, rich structure, and easy to obtain heteroatom by in-situ doping. Herein, Ni₂P–Fe₂P bimetallic phosphide spherical nanocages encapsulated in N/P-doped pine needles biochar is prepared via a simple two-step pyrolysis method. Benefiting from the maximum synergistic effects of bimetallic phosphide and biochar, high conductivity of biochar encapsulation, highly exposed active sites of Ni₂P–Fe₂P spherical nanocages, rapid mass transfer in porous channels with large specific surface area, and the promotion in adsorption of reaction intermediates by high-level heteroatom doping, the (Ni_0.75Fe_0.25)₂P@NP/C demonstrates excellent OER activity with an overpotential of 250 mV and a Tafel slope of 48 mV/dec at 10 mA/cm² in 1 M KOH. Also it exhibits a long-term durability in 10 h electrolysis and its activity even improves during the electrocatalytic process. The present work provides a favorable strategy for the inexpensive synthesis of biochar-based transition metal electrocatalysts toward OER, and improves the water electrolysis for hydrogen production.     

Carbon-supported non-noble metal single-atom catalysts for electro-catalytic hydrogen evolution reaction

Hydrogen – a renewable and clean energy is deemed as the best alternative to fossil fuels. Electro-catalytic hydrogen evolution reaction (HER) based on non-noble metals exhibits great potentials in recent years, especially at the atomic level. In this review, the reaction mechanisms of HER are firstly illustrated, followed by the introduction of preparation methods for single atom catalysts (SACs) supported on carbons. Subsequent sections consist of representative characterizations and simulation methods for SACs. After that, the applications of non-noble metal-based SACs/C catalysts in HER are discussed based on the metal type. During the discussion of their applications, the structure-performance relationships are elaborated in depth in terms of the design strategy, including the carbon matrix, heteroatom doping and bimetallic composition. Finally, the challenges and perspectives of electrolytic HER are proposed.     

Laser structured nickel-iron electrodes for oxygen evolution in alkaline water electrolysis

In the present work, the ultra-short pulse laser ablation method is applied to create novel surface alloys on NiFe electrodes for the oxygen evolution reaction (OER) in alkaline water electrolysis. The nickel-to-iron ratio in the alloy can be controlled with the ultra-short pulse laser ablation method by varying the thickness of electrochemically deposited iron layers onto the nickel mesh substrate. Besides the application of the additional catalyst, the laser treatment enhances the surface area and a defined micro- and submicrometer structure is created in a single step. The laser structured nickel-iron electrodes show a significantly lower overpotential of 249 mV than an electrochemically deposited Ni-NiFe alloy with 292 mV at 10 mA cm⁻², 298 K and 32.5 wt% KOH for the OER, although some loss of iron over time could not be prevented.     

Hydrogen evolution and oxygen evolution reactions of pristine and alkali metal doped SnSe2 monolayer

Many transition metal di-selenides such as MoSe₂ and WSe₂ show good catalytic activity on their edges with limited active orientations. These metal di-selenides are actively being used as target material for increasing the number of electrocatalytic active sites and in turn to improve the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities by increasing the ratio of edges to the basal plane. In present work, we have studied the activity of pristine and alkali atoms (Na, K and Ca) doped-SnSe₂ for HER and OER catalyst. The state-of-art density functional theory (DFT) based computations are performed for estimating the catalytic activity of the pristine and doped SnSe₂ by means of evaluating the adsorption and Gibbs free energies subjected to hydrogen and oxygen adsorption. Further, to get better prediction of adsorption energy on the individual catalytic surface, we have included the dispersion correction term to exchange-correlation functional. Results show that the pristine SnSe₂ is not a good HER catalyst when hydrogen is adsorbed on its basal plane. However, edge-sites show the good hydrogen adsorption and indicates that the edges of SnSe₂ are the most preferential site for hydrogen adsorption. As far as the catalytic activity of SnSe₂ with dopants is concerned, the Na-doped SnSe₂ among all shows the best catalytic activity over its edge-site; whereas K and Ca doped SnSe₂ show basal plane as preferred catalytic site. It is interesting to note that the disadvantage of low catalytic activity on basal plane of SnSe₂ can be improved by selective doping of alkali metals.     

Transition metal carbides coupled with nitrogen-doped carbon as efficient and stable Bi-functional catalysts for oxygen reduction reaction and hydrogen evolution reaction

Developing non-precious metal catalysts for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is crucial for proton exchange membrane fuel cell (PEMFC), metal-air batteries and water splitting. Here, we report a in-situ simple approach to synthesize ultra-small sized transition metal carbides (TMCs) nanoparticles coupled with nitrogen-doped carbon hybrids (TMCs/NC, including WC/NC, V₈C₇/NC and Mo₂C/NC). The TMCs/NC exhibit excellent ORR and HER performances in acidic electrolyte as bi-functional catalysts. The potential of WC/NC at the current density of 3.0 mA cm^?2 for ORR is 0.814 V (vs. reversible hydrogen electrode (RHE)), which is very close to Pt/C (0.827 V), making it one of the best TMCs based ORR catalysts in acidic electrolyte. Besides, the TMCs/NC exhibit excellent performances toward HER, the Mo₂C/NC only need an overpotential of 80 mV to drive the current density of 10 mA cm^?2, which is very close to Pt/C (37 mV), making it the competitive alternative candidate among the reported non-precious metal HER catalysts.     

Recent development in electrocatalysts for hydrogen production through water electrolysis

Hydrogen is a carbon-free alternative energy source for use in future energy frameworks with the advantages of environment-friendliness and high energy density. Among the numerous hydrogen production techniques, sustainable and high purity of hydrogen can be achieved by water electrolysis. Therefore, developing electrocatalysts for water electrolysis is an emerging field with great importance to the scientific community. On one hand, precious metals are typically used to study the two-half cell reactions, i.e., hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, precious metals (i.e., Pt, Au, Ru, Ag, etc.) as electrocatalysts are expensive and with low availability, which inhibits their practical application. Non-precious metal-based electrocatalysts on the other hand are abundant with low-cost and eco-friendliness and exhibit high electrical conductivity and electrocatalytic performance equivalent to those for noble metals. Thus, these electrocatalysts can replace precious materials in the water electrolysis process. However, considerable research effort must be devoted to the development of these cost-effective and efficient non-precious electrocatalysts. In this review article, we provide key fundamental knowledge of water electrolysis, progress, and challenges of the development of most-studied electrocatalysts in the most desirable electrolytic solutions: alkaline water electrolysis (AWE), solid-oxide electrolysis (SOE), and proton exchange membrane electrolysis (PEME). Lastly, we discuss remaining grand challenges, prospect, and future work with key recommendations that must be done prior to the full commercialization of water electrolysis systems.     

Novel alkaline water electrolysis with nickel-iron gas diffusion electrode for oxygen evolution

In the present work, a novel electrolyzer concept for alkaline water electrolysis (AEL) with a gas diffusion electrode (GDE) as anode, a conventional immersed porous cathode and a state-of-the-art Zirfon™ separator is presented and compared with a conventional electrolyzer setup. Due to the utilization of a GDE in this configuration, the electrolyte is only circulated through the cathode compartment which greatly simplifies the process. The influence of the catalyst composition and the enhanced electrode surface owing to the three-dimensional porous structure of the GDE are characterized and investigated regarding the electrode performance. Furthermore, process parameters like contact pressure and differential pressure are examined and optimized. The novel process concept with a GDE as anode reveals a similar cell potential compared to a classical electrolysis cell with a Ni/Fe-coated nickel foam anode up to 400 mA cm⁻² at 353 K and 32.5 wt% KOH and also exhibits relatively good electrochemical stability over time.     

A quinary high entropy metal oxide exhibiting robust and efficient bidirectional O2 reduction and water oxidation

The O₂/H₂O couple-based transformation between renewable energy and electricity has emerged as a key step in implementing a carbon-neutral energy infrastructure. Therefore, an inexpensive and efficient electrocatalyst driving both O₂ reduction and O₂ evolution reaction in water becomes critical that can be directly applied in a unitized regenerative fuel cell in both electrolyzer or fuel cell mode. Here, we have crafted a high entropy metal oxide (HEO) containing readily abundant first-row transition metals (Fe, Cr, Co, Mn, Ni) via a metal-organic framework intermediate followed by regulated annealing at 750 °C. This material exhibited bidirectional ORR and OER activity in alkaline aqueous media (pH 14.0) with excellent energy efficiency on either side, showcasing a difference of 0.79 V (while achieving 10 mA cm⁻² current density) and ∼90% Faradaic efficiency. The in-depth electrochemical and surface analysis pointed out the key formation of the Ni–OOH layer on the HEO particle and the optimal porosity for maximized electrochemical surface area generation as pivotal factors behind its superior reactivity. An alkaline electrolyzer was assembled with this HEO (anode) and Ni-foam (cathode), which demonstrated concurrent production of O₂ and H₂ over 6 h with minimal alterations in the anodic material. Therefore, this robust, inexpensive, and scalable HEO material can boost the progress in developing sustainable electrolyzer/fuel cell assemblies.     

High-throughput chainmail catalyst FeCo@C nanoparticle for oxygen evolution reaction

Oxygen evolution reaction (OER) is a key part of water electrolysis for hydrogen production. Non-noble-metal catalysts with high activity, stability, but low cost are prerequisites for practical application. In this work, sucrose char was synthesized and then chainmail catalysts were produced by in situ growth method, defined as M@C (M = Fe, Co and FeCo). FeCo@C showed great OER performance in both catalytic activity and durability tests. The overpotentials were 302 mV (at the current density of 10 mA cm⁻²) and 423 mV (at 50 mA cm⁻²), with a lowest Tafel slope of 75 mV dec⁻¹. The electrochemical surface area of catalysts were also analyzed by calculating the capacitance of the double layer to further investigate the catalytic activity. Furthermore, FeCo@C showed superior stability after 30 h test or 10,000 cycles of cyclic voltammetry. Theoretical calculation based on density functional theory (DFT) demonstrated that the overpotential of OER was determined by the Gibbs free energies of reaction intermediates HO1, O1 and HOO1. The adsorption of HO1 radicals onto the FeCo@C was weaker than Fe@C, which was favorable for reducing the overpotential, as the rate-determining step of the OER process over these catalysts was that HO1 dehydrogenated to form O1.     

Structure optimization and electronic modulation of sulfur-incorporated cobalt nanocages for enhanced oxygen evolution

Cobalt-based oxides and hydroxides have always been one of the optimal catalysts for Oxygen Evolution Reaction (OER) in alkaline environment in recent years. However, it remains a challenge for simple cobalt oxides such as CoO, Co₃O₄ and CoOOH to provide high catalytic activity both with ideal conductivity and stability. Herein, we prepared a new type of sulfur-incorporated cobalt oxide nanocages as high efficiency OER catalyst using Co-MOF as precursor. With the help of sodium sulfide, one step water-warm immersion-alcohol refluxing method can achieve the cavitation of precursors and uniform incorporation of sulfur atoms meanwhile. The hollow cubic structure constructed by fluffy nanosheets is beneficial to the exposure of active sites, the regulation of electronic structure and improve the electron transfer speed. After electrochemical testing, the prepared CoS@CoO showed outstanding OER activity compared with other cobalt-based catalysts. More importantly, this material has also withstood the electrochemical test of long range due to the stable structural foundation provided by Co-MOF. This work comes up with a new idea for OER activity promotion of hollow doped cobalt-based catalysts through morphology control and electronic structure optimization.