Carbon supported IrM(M= Fe,Ni,Co) alloy nanoparticles for the catalysis of hydrogen oxidation in acidic and alkaline medium  

碳载合金IrM(M=Fe,Ni,Co)纳米颗粒催化酸性与碱性介质中氢氧化反应（英文）

作　　者：廖建华[1] 丁炜[1] 陶思成 聂瑶[1] 李巍[1] 吴光平[1] 陈四国[1] 李莉[1] 魏子栋[1] 

机构地区：[1]重庆大学化学化工学院,重庆400044

出　　处：《Chinese Journal of Catalysis》2016年第7期1142-1148,共7页催化学报（英文）

基　　金：supported by the National Basic Research Program of China(973 Program,2012CB215500);the National Natural Science Foundation of China(21573029);the Fundamental Research Funds for the Central Universities(106112015CDJXY220002)

摘　　要：We studied the alloying effect in lr-based alloys on the catalysis of the hydrogen oxidation reaction （HOP,） in both acidic and alkaline medium. IrFe, lrNi and IrCo alloy catalysts with nanoparticle size of 〈S nm were obtained by our solvent-vaporization plus hydrogen reduction method. The second metal played an important role in tuning the crystal structure and surface electronic structure of the Ir-based alloy catalyst. Among the lrFe, IrCo and lrNi alloy catalysts, Ni induced a mid-sized contrac- tion of the lr lattice, and gave the best HOR activity in both acidic and alkaline medium. In acidic medium, the weakening of the Ir-Had interaction caused by the electronic effect of M （M = Fe, Ni, Co） alloying is responsible for the enhancement of HOR activity. The oxophilic effect of the catalytic metal surface, which affects OHad adsorption and desorption and surface Had coverage, has a large impact on the HOR activity in the case of alkaline medium,质子交换膜燃料电池(PEMFC)因能量转化率高、电流密度大、对负荷响应快及环境友好等优点而应用前景广阔.然而,Pt基催化剂的大量使用使得PEMFC成本居高不下,阻碍了其商业化进程.金属Ir具有良好的稳定性和相比Pt较低的成本,可替代金属Pt催化燃料电池阳极氢氧化反应.但是,Ir基催化剂的催化活性比Pt低,难以满足商业化要求.通过合金调控Ir纳米晶的电子结构和几何结构是降低Ir用量、提高Ir催化剂氢氧化活性的有效方法.本文研究了Ir基合金纳米晶中合金元素(Fe,Ni,Co)所产生的合金效应在酸碱性介质中对催化氢氧化的影响.采用溶剂蒸发-氢气还原法合成了具有相近合金度且平均粒径小于5 nm的Ir Fe,Ir Ni和Ir Co纳米合金催化剂.电化学测试表明,Ir Ni合金催化剂具有最高的催化氢氧化活性.在酸性介质中,Ir Ni合金催化剂的质量比活性达到152 A/gIr(@0.1 V vsRHE),高于Ir Fe(146 A/gIr)和Ir Co(133 A/gIr)合金催化剂以及商业化Pt/C催化剂(116 A/gPt).而在碱性介质中,Ir基合金催化剂活性较酸性介质中低,各合金催化剂优劣次序与酸性介质中一致.结构分析表明,合金化致使Ir晶格收缩,收缩程度以Ir Fe,Ir Ni和IrCo的顺序依次降低.Ir Ni合金催化剂中Ni合金元素诱导Ir发生晶格收缩适中,使催化剂与中间物种(H_(ad),OH_(ad))的相互作用适度,从而获得最优的催化性质.另外,合金效应在不同pH介质中影响不一:在酸性介质中,由合金元素(Fe,Ni,Co)导致的Ir–H_(ad)相互作用弱化是提高氢氧化活性的主要原因;在碱性介质中,催化剂表面的亲氧效应决定了电极表面的OH_(ad)吸/脱附性质和H_(ad)表面覆盖度,从而影响催化氢氧化活性.

关 键 词：Alloying effectHydrogen oxidation reactionIridium alloyLattice contractionFuel cell 

分 类 号：O643.36[理学—物理化学] TM911.4[理学—化学]