镍铁层状双金属氢氧化物在不同pH电解液体系中的析氧反应（英文）

利用可再生电力驱动水分解提供了一种绿色和可持续的方式来生产氢气(H₂),而提高水分解效率的关键是开发高效的电催化剂.作为水分解反应的阴极,析氢反应(HER)仅需要两电子转移,目前的研究较为成熟.相比之下,析氧反应(OER)因涉及四个电子的转移,比HER过程更复杂.在众多析氧催化剂中,镍铁(NiFe)基电催化剂是碱性电解液体系中最佳的OER催化剂之一,然而其在中性及近中性体系中活性降低较多,从而限制了其在中性的海水电解及二氧化碳还原体系中的应用.目前,造成NiFe基催化剂在中性体系中性能较差的具体机制尚不清晰.文献报道,随着体系pH逐渐降低,NiFe基催化剂析氧性能也会随之变差;深入研究发现,碱性体系中更易于形成高价的Ni,Fe物质,但其是否对催化剂在水分解过程中有影响仍有待进一步研究.本文将电化学测试与原位光谱技术相结合,对镍铁层状双金属氢氧化物(NiFe LDH)在不同pH电解液体系中的析氧反应机理进行深入研究.电化学测试结果表明,随着pH值逐渐降低,NiFe LDH催化剂的析氧性能逐渐变差.原位表面增强拉曼光谱结果表明,不同pH电解液体系中NiOOH和“活性氧...     

电催化析氧反应过渡金属磷化物和硫化物催化剂研究进展（英文）

对化石能源的依赖所造成的环境污染和能源危机在全球引起了广泛的关注.氢能由于其高能量密度、低分子质量以及清洁无污染的优点,被认为是人类根本性解决能源与环境等全球性问题的理想替代能源.电解水是生产高纯度氢的重要方法,是现代清洁能源技术的重要组成部分.水电解由阴极析氢(HER)和阳极析氧(OER)两个半反应构成.对于HER反应,其反应是基于二电子转移过程,反应过程相对容易进行.相比于HER反应,OER反应涉及四电子转移及氧-氧键形成,其反应动力学缓慢,是影响水电解效率的主要原因.因此,为了提高电解水制氢的能量转化效率,发展OER电催化剂成为水电解制氢技术的关键.在过去的十余年间,硫化物、硒化物、磷化物、硼化物等非贵金属基OER电催化剂被大量地研究及报道并取得了长足发展.在这些催化剂中,金属磷化物和硫化物不仅具有成本优势,而且在析氧过电位、耐久性方面正趋接近甚至超越RuO_2和IrO_2等贵金属催化剂,颇具应用潜力.本文总结磷化物和硫化物作为OER电催化剂的研究进展,重点介绍了磷化物和硫化物性能提升策略及其在OER过程中催化反应活性位的变化.本文首先介绍了电解水析氧反应在不同电解质中的反应机理,讨论了析氧反应在动力学和热力学过程的主要障碍.通过对大量文献的归纳,本文分别综述了磷化物和硫化物的化学性质、合成方法和催化性能,介绍了近年来磷化物和硫化物的重要研究进展.通过分析催化剂导电性、质子传输、活性面积、界面化学等因素对催化析氧反应的影响,总结了磷化物和硫化物电催化OER性能提升的策略.由于磷化物和硫化物在OER强氧化条件下,电催化剂表面的成分、物相及结构均会发生显著变化,进而催化反应活性位也会发生相应改变.本文综述了磷化物和硫化物在OER反应过程前后表面组分的变化,探讨了磷化物和硫化物作为OER电催化剂的活性组分,为进一步提高磷化物和硫化物的电催化析氧反应性能提供了崭新的思路.     

偶氮四唑钾盐的绿色电合成反应耦合WS2纳米片催化电解水制氢

析氧反应(OER)作为动力学缓慢的四电子多步骤反应过程,限制了电催化水分解制氢的反应速率,降低了电催化水分解制氢的整体效率,以热力学更有利的有机含能材料氧化反应替代OER与析氢反应(HER)耦合,在降低槽压制得氢气的同时能得到高附加值的化工产品.本文建立了一种新的耦合体系,在阳极侧制备含能离子盐[偶氮四唑钾盐(K₂AZT)]的同时,阴极侧以碳布负载的二硫化钨纳米片(CC@WS₂ NSs)作为HER催化剂促进H₂的形成.该体系仅需要1.65 V的槽电压即可达到10 m A/cm²的电流密度,相比于CC@WS₂ NSs/CF全解水体系(1.87 V)降低了220 m V.耦合体系在至少15 h内保持平稳运行,表现出优异的稳定性能.通过绿色安全的电化学法制备含能化合物避免了传统有机合成方法高能耗、高风险和高成本等问题,为安全生产含能材料提供了新的合成策略.     

高熵合金金属烯用于酸性条件下全水分解（英文）

质子交换膜水电解槽(PEMWE)因其在低温下的高效率和高功率密度,成为新一代电解槽的发展方向.在水的电解过程中,设计高效稳定的析氢反应(HER)和析氧反应(OER)催化剂是进一步提高电解槽应用的前提.根据HER和OER “火山型”分布曲线,贵金属(Ir,Ru等)依然是主要的基准电催化剂.对于酸性条件下全水分解,Ir基和Ru基双功能催化剂仍然是最常见的选择.然而,与Ir基催化剂相比,Ru基催化剂在酸性条件下的高溶解速率易导致催化剂快速失活,大大降低了其实际应用价值.目前,酸性条件下全水分解的Ir基催化剂也取得了一些成果,如合金(如PdCu/Ir,Au@AuIr₂,IrTe纳米棒和IrNi合金纳米花)、钙钛矿(如AIrO₃)、硒化物(如Li-IrSe₂)和团簇(如Ir纳米团簇,IrNi纳米团簇)等.然而,Ir基材料在高电流密度下仍然面临质量活性低和稳定性有限的挑战(100 mA cm^-2时的过电位超过420 mV,酸性整体水分解在高电流密度下的长期稳定性差).上述问题使得电催化剂无法满足PEMWE的应用...     

(Co,Ni) Se2/C@FeOOH中空笼状纳米结构的自旋调控加速水氧化催化研究

氢气作为一种清洁无污染的可再生能源,可以有效地解决全球能源危机和环境污染问题.低能耗水裂解制氢是公认的未来清洁制氢的有效途径之一.水裂解反应分为阳极上发生的析氧反应(OER)和阴极上发生的析氢反应,由于阳极半反应涉及四电子过程,反应动力学缓慢,进而导致整个水分解产氢效率低下,成为规模化水裂解制氢应用的瓶颈.贵金属Ir基...     

析氧反应中催化剂-电解质界面的质子动力学研究

电催化水分解是一种可持续的绿色产氢技术,该技术在工业化的大规模应用急需开发高效稳定的非贵金属催化剂,用于提高析氧反应(OER)的反应速率.研究发现,钙钛矿氧化物是优异的OER催化剂,但是对于发生在催化剂-电解质固液界面上的反应机理仍有争论.目前普遍认为,在OER反应过程中,水分子吸附在金属氧化物催化剂表面的金属活性中心...     

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。     

导电MOFs在能源转化中的应用

可再生能源供应方案包括析氢反应(HER)、析氧反应(OER)、氧还原反应(ORR)和二氧化碳还原反应(CO2RR)等多种反应,电催化剂对这些反应至关重要。到目前为止,已有一系列导电MOFs作为与能源相关电催化电极材料的报道。本文从提高MOFs导电能力和对产物的选择性、增强MOFs的化学稳定性及增加MOFs的反应活性位点等方面介绍了导电MOFs作为电催化剂的设计策略,重点综述了其在能源转化涉及的HER、OER、ORR以及CO2RR方面的应用,并从材料制备和应用需求角度出发, 对高性能导电MOFs材料在电催化领域所面临的挑战和前景进行了展望。     

一种高效的非晶态Co(OH)2水氧化电催化剂

电催化氧化水包括析氧和析氢两个半反应(OER和HER),而其中合成高效廉价的催化剂则至关重要.合成了在碱性溶液中具有高活性、良好稳定性的非晶态Co(OH)_2纳米材料用于析氧反应催化剂,实验证明该材料的性能可以和商用RuO_2相媲美.与目前商用的RuO_2催化剂相比,非晶态Co(OH)_2材料的塔菲尔斜率较小,仅为67 mV/decade,且经过24 h的电流i-t曲线测试衰减较少.此外,该非晶态Co(OH)_2纳米管的性能优于晶态Co(OH)_2纳米管.因此,非晶态Co(OH)_2纳米材料是一种很有前途的析氧反应催化剂.     

血小板状Ru掺杂Ni2P纳米催化剂的合成及其双功能电催化析氢和析氧性能

采用简单的一锅法制备了血小板状Ru掺杂Ni_2P纳米片催化剂。金属Ru的引入不但显著增强了催化剂的电子传输性能,而且导致血小板状纳米片表面产生了大量阶梯/位错缺陷;此外,电催化活性位点测试表明Ru和Ni_2P均是电催化的有效活性组分。这些因素共同促进了电催化析氢(HER)和析氧反应(OER)过程。对于HER,该催化剂表现出明显优于单一Ni_2P和Ru且接近商用20%(w/w)Pt/C催化剂的初始电位(35 mV)和Tafel斜率(34 mV·dec~(-1))以及长久的稳定性(3 000圈)。对于OER,该催化剂表现出优于Ni_2P、Ru、20%Pt/C且接近商用IrO_2催化剂的初始电位(1.54 V)和过电势η10(0.49 V)。     

Electrodeposited Cobalt‐Phosphorous‐Derived Films as Competent Bifunctional Catalysts for Overall Water Splitting

One of the challenges to realize large‐scale water splitting is the lack of active and low‐cost electrocatalysts for its two half reactions: H₂ and O₂ evolution reactions (HER and OER). Herein, we report that cobalt‐phosphorous‐derived films (Co‐P) can act as bifunctional catalysts for overall water splitting. The as‐prepared Co‐P films exhibited remarkable catalytic performance for both HER and OER in alkaline media, with a current density of 10 mA cm^?2 at overpotentials of ?94 mV for HER and 345 mV for OER and Tafel slopes of 42 and 47 mV/dec, respectively. They can be employed as catalysts on both anode and cathode for overall water splitting with 100 % Faradaic efficiency, rivalling the integrated performance of Pt and IrO₂. The major composition of the as‐prepared and post‐HER films are metallic cobalt and cobalt phosphide, which partially evolved to cobalt oxide during OER.     

Ru−FeNi Alloy Heterojunctions on Lignin-derived Carbon as Bifunctional Electrocatalysts for Efficient Overall Water Splitting

Rational design of efficient, stable, and inexpensive bifunctional electrocatalysts for oxygen evolution reactions (OER) and hydrogen evolution reactions (HER) is a key challenge to realize green hydrogen production via electrolytic water splitting. Herein, Ru nanoparticles and FeNi alloy heterojunction catalyst (Ru−FeNi@NLC) encapsulated via lignin-derived carbon was prepared by self-assembly precipitation and in situ pyrolysis. The designed catalyst displays excellent performance at 10 mA cm⁻² with low overpotentials of 36 mV for HER and 198 mV for OER, and only needs 1.48 V for overall water splitting. Results and DFT calculations show the unique N-doped lignin-derived carbon layer and Ru−FeNi heterojunction contribute to optimized electronic structure for enhancing electron transfer, balanced free energy of reactants and intermediates in the sorption/desorption process, and significantly reduced reaction energy barrier for the HER and OER rate-determining steps, thus improved reaction kinetics. This work provides a new in situ pyrolysis doping strategy based on renewable biomass for the construction of highly active, stable and cost-effective catalysts.     

Hierarchical NiCo2O4 Hollow Microcuboids as Bifunctional Electrocatalysts for Overall Water‐Splitting

Bifunctional electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline electrolyte may improve the efficiency of overall water splitting. Nickel cobaltite (NiCo₂O₄) has been considered a promising electrode material for the OER. However, NiCo₂O₄ that can be used as an electrocatalyst in HER has not been studied yet. Herein, we report self‐assembled hierarchical NiCo₂O₄ hollow microcuboids for overall water splitting including both the HER and OER reactions. The NiCo₂O₄ electrode shows excellent activity toward overall water splitting, with 10 mA cm^?2 water‐splitting current reached by applying just 1.65 V and 20 mA cm^?2 by applying just 1.74 V across the two electrodes. The synthesis of NiCo₂O₄ microflowers confirms the importance of structural features for high‐performance overall water splitting.     

High-performance electrocatalyst of vanadium-iron bimetal organic framework arrays on nickel foam for overall water splitting

The development of active,low-cost and durable bifunctional electrocatalysts toward both oxygen evolution reaction(OER) and hydro gen evolution react ion(HER) a re important for overall water splitting.Here,well-defined arrays of vanadium-iron bimetal organic frameworks(VFe-MOF) with controllable stoichiometry have been successfully prepared on nickel foam(NF).The as-fabricated VFe-MOF@NF electrode exhibits excellent electrocatalytic activity and durability for OER and HER in alkaline medium.The material's overpotentials of 10 mA/cm~2 are 246 mV for OER and 147 mV for HER,respectively.The electrolyzer made from the VFe-MOF@NF electrodes as both the cathode and anode in 1 mol/L KOH needs only a voltage of 1.61 V to reach a current density of 10 mA/cm~2.The superior performance of VFeMOF@NF can be attributed to the morphological control and electronic regulation of the bimetals,that is,1) the exposure of the active sites at electrocatalyst/electrolyte interfaces due to the array structure;2)the synergistic effect of vanadium and iron metals on electro-catalyzing the overall water splitting.     

Synthesis of multi-unit protein hetero-complexes in the gas phase via ion-ion chemistry

The synthesis of protein hetero-complex ions via ion-ion reactions in the gas phase is demonstrated in a quadrupole ion trap. Bovine cytochrome c cations and bovine ubiquitin anions are used as reactant species in the stepwise construction of complexes containing as many as six protein sub-units. For any set of reactants, a series of competitive and consecutive reactions is possible. The yield of complex ions for any given sequence of reactions is primarily limited by the presence of competitive reactions. Proton transfer represents the most important competitive reaction that adversely affects protein complex synthesis. In the present data, proton transfer takes place most extensively in the first step of complex synthesis, when single protein sub-units are subjected to reaction with one another. Proton transfer is found to be less extensive when one of the reactants is a protein complex. The generation of hexameric hetero-complexes containing two cytochrome c molecules and four ubiquitin molecules is demonstrated with two different synthesis approaches. The first involved the initial reaction of several charge states of cytochrome c and several charges states of ubiquitin. The sequence of reactions in this example illustrates the array of possible competitive and consecutive reactions associated with even a relatively simple set of multiply charged reactants. The second approach involved the initial reaction of the 9(+) charge state of cytochrome c and the 5(-) charge state of ubiquitin. The latter approach highlights the utility of the multi-stage mass spectrometric (MS(n)) capabilities of the ion trap in defining reactant ion identities (i.e. charge states and polarities) so that synthesis reactions can be directed along a particular set of pathways.     

Proton transfer and the mobilities of the H+ and OH- ions from studies of a dissociating model for water

Hydrogen (H(+)) and hydroxide (OH(-)) ions in aqueous solution have anomalously large diffusion coefficients, and the mobility of the H(+) ion is nearly twice that of the OH(-) ion. We describe molecular dynamics simulations of a dissociating model for liquid water based on scaling the interatomic potential for water developed by Ojama?e-Shavitt-Singer from ab initio studies at the MP2 level. We use the scaled model to study proton transfer that occurs in the transport of hydrogen and hydroxide ions in acidic and basic solutions containing 215 water molecules. The model supports the Eigen-Zundel-Eigen mechanism of proton transfer in acidic solutions and the transient hyper-coordination of the hydroxide ion in weakly basic solutions at room temperature. The free energy barriers for proton transport are low indicating significant proton delocalization accompanying proton transfer in acidic and basic solutions. The reorientation dynamics of the hydroxide ion suggests changes in the proportions of hyper-coordinated species with temperature. The mobilities of the hydrogen and hydroxide ions and their temperature dependence between 0 and 50 °C are in excellent agreement with experiment and the reasons for the large difference in the mobilities of the two ions are discussed. The model and methods described provide a novel approach to studies of liquid water, proton transfer, and acid-base reactions in aqueous solutions, channels, and interfaces.     

非晶非贵金属催化剂的研究进展及展望

近年来电解水产氢作为一种具有前景的制备及储存可再生能源的方法受到了各界的广泛关注.在此过程中,电解水催化剂是提高能源转换效率的关键.优秀的催化剂应具备高催化活性、高稳定性、低成本以及可大规模生产等性质.科研工作者对电解水的两部分反应,即析氢反应以及析氧反应均进行了广泛及深入的研究.目前,贵金属催化剂,如铂基、钌基催化剂的催化活性要高于其他元素催化剂,但由于其价格昂贵,储量较少使得贵金属催化剂无法得到大规模应用,因此发展非贵金属催化剂对绿色能源的发展具有重要意义.一般而言,催化剂的结晶度越高,其催化活性越好,而近年来非晶催化剂以其更高的催化活性位密度也越来越受到人们的重视.同时,非晶催化剂的成分更加灵活,相比晶体催化剂来说非晶催化剂可以在更大范围内对成分进行调节.此外,非晶催化剂的制备通常都在较为温和的反应条件下进行,这也能够降低生成成本,促进其工业化发展.在这篇综述里我们介绍了电解水反应的基本原理,总结了近期非晶析氢、析氧以及双功能催化剂的研究进展.并随后探讨了电解水反应目前的难点并对非晶催化剂的制备进行了展望.     

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.     

Constructing the heterostructure of sulfide and layered double hydroxide as bifunctional electrocatalyst for overall water splitting

Journal of Solid State Electrochemistry - The rational design of bifunctional electrocatalyst for water splitting that involves hydrogen and oxygen evolution reactions (HER and OER) is important...     

Boosting Hydrogen Production by Anodic Oxidation of Primary Amines over a NiSe Nanorod Electrode

For electrocatalytic water splitting, the sluggish anodic oxygen evolution reaction (OER) restricts the cathodic hydrogen evolution reaction (HER). Therefore, developing an alternative anodic reaction with accelerating kinetics to produce value‐added chemicals, especially coupled with HER, is of great importance. Now, a thermodynamically more favorable primary amine (?CH₂?NH₂) electrooxidation catalyzed by NiSe nanorod arrays in water is reported to replace OER for enhancing HER. The increased H₂ production can be obtained at cathode; meanwhile, a variety of aromatic and aliphatic primary amines are selectively electrooxidized to nitriles with good yields at the anode. Mechanistic investigations suggest that Ni^II/Ni^III may serve as the redox active species for the primary amines transformation. Hydrophobic nitrile products can readily escape from aqueous electrolyte/electrode interface, avoiding the deactivation of the catalyst and thus contributing to continuous gram‐scale synthesis.