碱性水电解非贵金属析氧催化剂的研究进展

"绿氢"能源的大规模应用依赖于电解水技术。和析氢反应(HER)相比,析氧反应(OER)是水电解过程中的关键反应,其动力学反应缓慢。目前,非贵金属OER电催化剂的活性和稳定性不佳,深入OER过程机理的理解和催化剂活性方面的研究有助于OER速率的提升。文章综述了近年来在碱性体系中对水电解制氢非贵金属析氧催化剂的研究讨论、分析和总结,主要从材料掺杂类、形貌调控类、调节电子结构类和复合结构类4个方面来阐述。     

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。     

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。     

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。     

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。     

电化学氧还原反应合成H2O2碳基催化剂研究进展

电化学氧还原反应(ORR)合成H2O2是一种低成本、无污染的绿色合成方法.但是,ORR动力学缓慢,存在四电子ORR生成H2O的竞争反应,因此需要使用催化剂提升ORR的反应活性以及二电子ORR的选择性.近年来,碳基材料因价格便宜、来源广泛、调控方法多样,被广泛应用于该领域.本文首先简要介绍了电催化ORR合成H2O2的机理,并根据机理分析了影响电化学合成H2O2催化性能的关键因素.接着阐述了提升碳基ORR催化剂活性与二电子选择性的策略,并着重介绍了非金属原子掺杂碳材料和过渡金属氮碳材料.最后,总结了碳基催化剂在电化学合成H2O2中存在的问题和面临的挑战,对碳基催化剂在电合成H2O2中应用的发展趋势进行了展望.     

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.     

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。     

NiCoFe LDH阳极析氧催化剂的制备及性能研究

通过水热法高效地制备出三元过渡金属NiCoFe层状双氢氧化物(LDH)超薄纳米片.作为OER催化剂,NiCoFe LDH/NF在1.0 mol/L KOH溶液中表现出卓越的活性和良好的稳定性,当电流密度为120 mA/cm2时,过电位仅需200 mV,Tafel斜率为82 mV/(°),相较于常规水热法制备的NiCoF...     

Oxygen evolution NiOOH catalyst assisted V2O5@BiVO4 inverse opal hetero-structure for solar water oxidation

Using vanadium oxide (V₂O₅) inverse opal (IO) as a three-dimensional (3D) electron transporting tunnel, bismuth vanadate (BiVO₄) as a light harvester, and Amorphous Nickel Hydroxide (NiOOH) as an oxygen evolution co-catalyst, a V₂O₅@BiVO₄@NiOOH IO architecture was fabricated as an efficient photoanode on a conductive fluorine doped tin oxide (FTO) substrate for photoelectrochemical (PEC) water oxidation. V₂O₅ is the visible light absorbing photoanodes for water oxidation; however, the efficiency of this compound remains low (∼0.08 mA/cm² at 1.23 V vs. reversible hydrogen electrode (V_RHE)) and the unfavorable surface trap states limits the activity of V₂O₅ photoelectrodes in a PEC system. We found that the photoactive thin conductive BiVO₄ (∼12 nm) in the V₂O₅ IO greatly enhanced the charge separation efficiency to achieve better PEC water oxidation through modification of the surface states. The subsequent addition of NiOOH as an effective Oxygen evolution catalyst subsequently reduces the large overpotential and generates the photocurrent density of 1.14 mA/cm² at 1.23 V_RHE. Electrochemical impedance spectroscopy (EIS) evidenced that NiOOH deposition can substantially lower the charge transfer resistance (R_ct) at the semiconductor interface. Specifically, the consecutive and ordered morphology renders direct conduction pathways for the extraction of photogenerated electron/hole pairs and the convenient structure to penetrate the photogenerated carriers toward the semiconductor surface over the electrolyte. It is expected that the uninterrupted pathways will improve the electron transportation and thus the charge collection properties.     

Bimetallic metal-organic framework derived electrocatalyst for efficient overall water splitting

The development of bifunctional catalysts that can be applied to both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is widely regarded as a key factor in the production of sustainable hydrogen fuel by electrochemical water splitting. In this work, we present a high-performance electrocatalyst based on nickel-cobalt metal-organic frameworks for overall water splitting. The as-obtained catalyst shows low overpotential to reaches the current density of 10 mA cm⁻² with 249 mV for OER and 143 mV for HER in alkaline media, respectively. More importantly, when the electrolyzer was assembled with the as-prepared catalyst as anode and cathode simultaneously, it demonstrates excellent activity just applies a potential of 1.68 V to achieve 10 mA cm⁻² current density for overall water splitting.     

Electrocatalysts for hydrogen evolution reaction

In addition to the historical importance of water electrolysis, hydrogen evolution reaction (HER) is the heart of various energy storage and conversation systems in the future of renewable energy. The HER electrocatalysis can be well conducted by Pt with a low overpotential close to zero and a Tafel slope around 30 mV dec^?1; however, the practical developments to satisfy the growing demands require cheaper electrocatalysts. Noble metals are still the promising candidates, though further improvement is needed to enhance the HER efficiency in performance. Three categories of non-noble metal electrocatalysts are under heavy investigations: (i) alloys, (ii) transition metal compounds, and (iii) carbonaceous nanomaterials. The most practical option, based on the electrocatalytic activity and electrochemical stability, seems to be the transition metal compounds MX (where M is Mo, W, Ni, Co, etc. and X is S, Se, P, C, N, etc.). Among these compounds, some like MoS₂ and WC can display metallic properties and a Pt-like electrocatalytic activity, but they still need serious modifications for the practical performance. In general, similar strategies have been employed to improve the HER performance of all of these materials such as doping (both cation and anion), controlling the crystallinity and amorphism, and increasing the active sites by changing the morphology. Another important issue is the chemical and physical structure of the carbon-based catalyst support, as carbon is normally a vital component even for the Pt electrocatalysts.     

Role of perovskites as a bi-functional catalyst for electrochemical water splitting: A review

The electrochemical water splitting by using renewable electricity is being considered as a sustainable, clean and considerable source of hydrogen fuel for future transportation and energy applications. The sluggish kinetics at anode and cathode, thus, require plenty of research work on the development of an efficient and stable electrocatalyst, which would provide the enhanced activity of water splitting reaction as well as stability for long-term operation. This review draws a detailed sketch of the progress in the pursuit of replacing noble metals with non-precious perovskite-based substitutes without compromising the key electrocatalyst characteristics. Herein, we critically analysed the latest research work and progress of perovskite oxides for anodic/oxygen reduction reaction/cathodic, including the mechanism behind perovskite oxide catalytic reactions, controlled composition as well as the role of various design strategies to achieve high catalytic performance. Moreover, the article also provides an insight to the associated density functional theory that can provide profound understanding of mechanism, involved behind these reactions and, the need for computational studies to exploit the active area of catalysts. It is believed that this article will assist researchers to explore key area of research in the current generation perovskites that show enhanced catalytic performance as well as to work on unforeseen challenges.     

Facile route to achieve MoSe2-Ni3Se2 on nickel foam as efficient dual functional electrocatalysts for overall water splitting

Since the catalytic activity of present nickel-based synthetic selenide is still to be improved, MoSe₂-Ni₃Se₂ was synthesized on nickel foam (NF) (MoSe₂-Ni₃Se₂/NF) by introducing a molybdenum source. After the molybdenum source was introduced, the surface of the catalyst changed from a single-phase structure to a multi-phase structure. The catalyst surface with enriched active sites and the synergistic effect of MoSe₂ and Ni₃Se₂ together enhance the hydrogen evolution reactions (HER), the oxygen evolution reactions (OER), and electrocatalytic total water splitting activity of the catalyst. The overpotential of the MoSe₂-Ni₃Se₂/NF electrocatalyst is only 259 mV and 395 mV at a current density of 100 mA/cm² for HER and OER, respectively. MoSe₂-Ni₃Se₂/NF with a two-electrode system attains a current density of 10 mA/cm² at 1.60 V. In addition, the overpotential of HER and OER of MoSe₂-Ni₃Se₂/NF within 80000 s and the decomposition voltage of electrocatalytic total water decomposition hardly changed, showing an extremely strong stability. The improvement of MoSe₂-Ni₃Se₂/NF catalytic activity is attributed to the establishment of the multi-phase structure and the optimized inoculation of the multi-component and multi-interface.     

Synthesis and electrocatalytic activity of Ni0.85Se/MoS2 for hydrogen evolution reaction

Recently, the replacement of expensive platinum-based catalytic materials with non-precious metal materials to electrolyze water for hydrogen separation has attracted much attention. In this work, Ni_0.85Se, MoS₂ and their composite Ni_0.85Se/MoS₂ with different mole ratios are prepared successfully, as electrocatalysts to catalyze the hydrogen evolution reaction (HER) in water splitting. The result shows that MoS₂/Ni_0.85Se with a molar ratio of Mo/Ni = 30 (denoted as M30) has the best catalytic performance towards HER, with the lowest overpotential of 118 mV at 10 mA cm⁻², smallest Tafel slope of 49 mV·dec⁻¹ among all the synthesized materials. Long-term electrochemical testing shows that M30 has good stability for HER over at least 30 h. These results maybe due to the large electrochemical active surface area and high conductivity. This work shows that transition metal selenides and sulfides can form effective electrocatalyst for HER.     

Study of cobalt boride-derived electrocatalysts for overall water splitting

The production of clean hydrogen fuel by the electrolysis of water requires highly active, low-cost and facilely prepared electrocatalyst that minimizes energy consumption. Here we report an active cobalt boride (CoB)-derived electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The CoB catalyst can be readily deposed on 3D nickel foam (NF) using a simple electroless plating method. A comprehensive analysis of the CoB catalyst with scanning electron microscopy transmission (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques revealed that CoOOH is formed on the surface of CoB catalyst during the OER process and Co(OH)₂ is formed in the HER process. The catalyst derived from CoB/NF exhibits low overpotentials towards both OER and HER in alkaline solution. The electrolysis cell using the CoB-derived catalyst couple requires a cell voltage of 1.69 V to afford a current density of 10 mA/cm², which compares favorably with most non-noble bifunctional electrocatalysts. The favorable combination of high-performance, low cost and facile preparation suggests that transition metal borides may act as promising electrocatalyst for water splitting.     

Low Ir-content Ir/Fe@NCNT bifunctional catalyst for efficient water splitting

In order to reduce the cost of electrocatalysts and increase the exposure of the Ir active sites while ensuring the stability of the catalyst, a N-doped carbon nanotube (NCNT) is applied as a conductive support to confine the Ir clusters for avoiding them growing up via a modified method based on pyrolysis of a mixture of melamine, ferric chloride and iridium trichloride. It is found that Ir species in the as-obtained Ir(20)/Fe@NCNT-900 composite exist in two forms, Ir nanoclusters (1–2 nm) dotted on the wall of NCNT and the Ir atomically scattered on the Fe nanoparticles wrapped in the NCNT. Although the Ir content of Ir(20)/Fe@NCNT-900 is extremely low (～4 wt% Ir), the composite catalyst delivers excellent activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with an exceptionally low overpotential of 4.7 mV/11 mV for HER and 300 mV/270 mV for OER to drive 10 mA cm^?2 in 0.5 M H₂SO₄/1.0 M KOH electrolyte respectively, which exceeds the commercial Pt/C (20 wt% Pt) and IrO₂ benchmarks. In addition, it has much higher mass activity for OER at 1.55 V (1.78 A mg^?1_Ir) than those of the referenced catalysts in acid. The cell voltage of the two-electrode system assembled by Ir(20)/Fe@NCNT-900 for total water splitting in acidic and alkaline media are only 1.520 V and 1.510 V to afford 10 mA cm^?2 separately, lower than that of Pt/C||IrO₂ and with a good stability. Our work provides a construction method of low-content precious metal composite catalysts which can be applied in OER and overall water splitting field.     

Experimental study and analytical modeling of an alkaline water electrolysis cell

A traditional alkaline aqueous electrolyzer is investigated by using a 3‐electode structure that enables the reaction resistance of each individual electrode to be accurately monitored. Combining experimental observations with resistance‐based model analysis, we establish a quantitative relationship between current density and key voltage losses, including losses due to thermodynamics, kinetics, ohmic, and mass transport. These results demonstrate that the oxygen evolution reaction and bubble effects play crucial roles in determining electrolyzer performance. By varying the distance between electrodes, 2 effective OH^? conductivities in 0.4M KOH are found to be 0.1333 and 0.9650 second cm^?1, depending on bubble formation and release rate at the electrode interface. Moreover, bubble coverage on electrode surface achieves a steady state of 96% when current density is above 0.1 A cm^?2. In the study of various electrolyte concentrations, all the model predictions show good agreement with experimental results, confirming its ability to capture actual cell performance. This newly presented empirical resistance‐based model provides a practical framework to simulate complicated electrolysis reactions, serving as a comprehensive guide for continuous improvement of water electrolysis.