甲醇在欠电位沉积Ru修饰Pt电极上的催化氧化

采用欠电位沉积(upd)方法在Pt 表面沉积亚单层的Ru制备出upd-Ru/Pt 电极. 通过欠电位沉积前后电极在0.5 mol·L-1 H2SO4溶液中循环伏安图-152 - 128 mV(vs Ag/AgCl)电位范围内对氢区的数值积分确定Pt表面Ru 的覆盖度. 用电化学方法测试了甲醇在upd-Ru/Pt电极上的催化氧化, 并讨论分析了欠电位沉积电位和Ru的表面覆盖度对甲醇氧化的影响. 结果表明, Ru能够欠电位沉积到Pt表面. Pt表面欠电位沉积少量的Ru 即能大大促进甲醇的氧化.只要控制upd-Ru的沉积量, upd-Ru原子就能大大促进甲醇氧化而与沉积电位无关. Ru原子对甲醇氧化的促进作用与Ru和Pt是否形成合金无关, 而取决于Ru 在Pt表面的百分含量.

Methanol Oxidation on a Pt Electrode Modified by Underpotential Deposition of Ru

Underpotential deposition (upd) of rutheniumon a platinumelectrode was adopted to obtain a submonolayer of ruthenium on platinum surface. Ru coverage was evaluated according to the change of the hydrogen desorption area in the cyclic voltammograms (CV) of Pt electrodes before and after upd-Ru modification in 0.5 mol·L-1 H2SO4. The effectsof the potential for formation of upd-Ru and coverage of upd-Ru adtoms on methanol oxidation were investigated and analyzed. It was shown that Ru adatoms could be underpotentially deposited on a platinum surface. The submonolayer of upd-Ru on the Pt electrode could enhance methanol electrooxidation several times as large as that on the pure Pt electrode. It was also shown that as long as the amount of upd-Ru adatoms was controlled in a proper range, upd-Ru deposits would enhance the methanol oxidation independently of the deposition potential. The catalytic activity of binary Pt-Ru catalysts for methanol electrooxidation was highly associated with the surface composition of Pt and Ru, but was free of whether Pt-Ru deposits appear in a formof alloy, bimetallic compounds, adatoms, or something else.