吸附态和溶液相CO在Pt(110)电极上氧化过程的CV和in situ FTIRS 研究

Studies of oxidation Processes of Adsorbed and Solution CO on Pt(110) Electrode by Cyclic Voltammetry and in situ FTIRS

应用电化学原位傅里叶变换红外反射光谱(in situ FTIRS)研究了酸性介质中Pt(110)单晶电极上吸附态CO(COad)和溶液相CO(COsol)的氧化过程.循环伏安测试表明,COsol氧化的峰电位比COad氧化的正移了168mV,其峰电流密度为后者的6.7倍.电化学原位红外光谱检测到CO主要生成线型的吸附态物种(COL),均匀分布在Pt(110)表面上.当溶液中不存在CO时,COL仅在电位高于0.15V才发生氧化.而且,该谱峰在其稳定吸附的电位区间内随电位增加蓝移,Stark系数为30cm-1·V-1;在COL发生氧化的电位区间,其谱峰强度随电位增加减小、峰位红移,线性变化率为-56cm-1·V-1.溶液中饱和CO时,原位红外光谱在-0.05V即可检测到CO2的存在,显示COL起始氧化的电位提前了200mV;电位高于-0.05V,该谱峰即发生红移,对应的线性变化率为-26.5cm-1·V-1.

The oxidation processes of adsorbed CO （COad） and solution phase CO （COsol） on Pt（110） electrode were investigated by cyclic voltammetry and in-situ FTIR spectroscopy. It has revealed that in comparison with COad on Pt（110） in a CO-free solution,the oxidation current peak of COsol in a CO-saturated solution is positively shifted ca. 168 mV,and the peak current density has been increased by 6. 70 times. Linear adsorbed CO （COL） is determined by in-situ FTIR spectroscopy as the main species,which is uniformly distributed on Pt （110） surface. In a CO-free solution,the onset potential of COL is measured by in-situ FTIRS ca. 0. 15 V; the COL band is blue-shifted with the increase of electrode potential in the potential range where COL is stable,yielding a Stark tuning rate 30 cm -1·V -1; when the COL is oxidized at E 0. 15 V,the COL band is red-shifted at a rate of - 56 cm -1·V -1. In the case of CO-saturated solution,the CO2 band could be appeared in the in-situ FTIR spectrum recorded at - 0. 05 V,demonstrating that the onset potential of COL oxidation is negatively shifted ca. 200 mV in comparison with Pt（ 110） in a CO-free solution; the COL band is immediately red-shifted with a rate of - 26. 5 cm -1·V -1 when the potential is above - 0. 05 V.