镍基金属有机框架及其衍生物在电催化析氧反应中的研究进展

作为未来最有潜力的制氢技术之一,电解水为解决环境污染和能源危机等问题提供了一种有效的解决途径。然而,阳极析氧反应缓慢的动力学和较高的过电位使其成为电解水装置效率提升的主要瓶颈。因此,开发高活性和高稳定性的析氧反应催化剂对于电解水技术的发展具有重要意义。近年来,镍基金属有机框架材料因其具有丰富可调的拓扑结构、较大的比表面积以及多孔特性,在催化领域受到了越来越多的关注。本文综述了镍基金属有机框架及其衍生材料在析氧催化研究中的最新进展。首先简要介绍了镍基材料在析氧反应中的原理及评价析氧催化剂活性的一些重要参数,并列举了几种镍基金属有机框架材料的结构及其在催化中的优势。随后,结合近年来发表的文献,对单金属、双金属和三金属镍基金属有机框架材料及其衍生物在析氧催化中的研究进展进行了总结与讨论,重点分析了该类材料的设计策略和催化机理。最后对该领域目前所面临的主要挑战以及未来的发展趋势进行了总结与展望。

Antimony oxides-protected ultrathin Ir-Sb nanowires as bifunctional hydrogen electrocatalysts

Developing electrocatalysts with fast kinetics and long-term stability for alkaline hydrogen oxidation reaction(HOR)and hydrogen evolution reaction(HER)is of considerable importance for the industrial production of green and sustainable energy.Here,an ultrathin Ir-Sb nanowires(Ir-Sb NWs)protected by antimony oxides(SbO_(x))was synthesized as an efficient bifunctional catalyst for both HOR and HER under alkaline media.Except from the much higher mass activities of Ir-Sb nanowires than those of Ir nanowires(Ir NWs)and commercial Pt/C,the SbO_(x) protective layer also contributes to the maintenance of morphology and anti-CO poisoning ability,leading to the long-term cycling performance in the presence of CO.Specifically,the Ir-Sb NW/SbO_(x) exhibits the highest catalytic activities,which are about 3.5 and 4.8 times to those of Ir NW/C and commercial Pt/C toward HOR,respectively.This work provides that the ultrathin morphology and H_(2)O-occupied Sb sites can exert the intrinsic high activity of Ir and effectively optimize the absorption of OH*both in alkaline HER/HOR electrolysis.

Single-Site Cu-Doped PdSn Wavy Nanowires for Highly Active,Stable,and CO-Tolerant Ethanol Oxidation Electrocatalysis

Developing a catalyst to break the tradeoff relation-ship between the catalytic activity and antipoisoning property toward the ethanol oxidation reaction(EOR)is of critical importance to the development of direct ethanol fuel cells(DEFCs),but remains challenging.Here,we developed a unique class of single-site Cu-doped PdSn wavy nanowires(denoted as SS Cu−PdSn WNWs)with promoted activity and durability toward alkaline EOR.Detailed characterizations reveal the atomic isolation of Cu species dispersed on the surface of the PdSn WNWs with distinct wavy structure and grain boundaries.The created SS Cu−PdSn WNWs exhibit an enhanced EOR performance in terms of mass activity,which is higher than those of PdSn WNWs,commercial Pd black,and commercial Pd/C,respectively.Moreover,the SS Cu−PdSn WNWs can also show improved stability as compared to other catalysts due to the improved antipoisoning property from the unique surface anchoring structure.Further investigations demonstrate that the doped SS Cu can strongly inhibit the adsorption of CO and promote the reaction process of EOR.DFT results reveal that the doped Cu shifts down the d-band center of PdSn,thereby modifying the adsorption of intermediates and reducing the reaction barrier of EOR.This work maps a pathway for optimally boosting EOR performance with surface engineering via atomic doping.

富含缺陷的非晶态与晶态杂化介孔钴钼纳米片高效析氧催化剂

构建具有丰富缺陷且缺陷浓度可调的二维(2D)介孔金属氧化物(氢氧化物)纳米材料作为高效电催化剂仍然是一个巨大的挑战.本工作开发了一种简便有效的一锅溶剂热路线来合成由晶体相Mo_(4)O_(11)和准非晶相氢氧化钴组成的介孔Mo_(x)-Co-O杂化纳米片.由于短链有机胺在高温下的刻蚀作用,合成过程中在Mo_(x)-Co-O杂化纳米片上原位产生了大量的介孔空穴,增加了材料的电化学比表面积.此外,Mo_(x)-Co-O纳米片的尺寸、介孔和晶相/非晶相纳米片上缺陷(本工作中的氧空位)的浓度可以通过控制Mo/Co摩尔比调节.电化学测试表明,2D介孔Mo_(x)-Co-O纳米片表现出优异的析氧反应活性,其中Mo_(0.2)-Co-O纳米片表现出最高的催化活性(在1 mol L^(−1)KOH中10 mA cm^(−2)处的过电位为276 mV).研究发现,Mo_(0.2)-Co-O纳米片具有合适的d带中心和最高浓度的氧空位,这是促成其优异催化活性的两个主要因素.本工作构建具有丰富缺陷(氧空位)和合适d带中心的二维金属氧化物(氢氧化物)的晶相/非晶杂化纳米材料的方法,为设计更高效的催化剂提供了重要启发.