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吸附硫通常被认为是表面化学反应毒物,然而少量的硫能够增强铂的一氧化碳(CO)电氧化活性.本文利用常规电化学手段及表面增强拉曼光谱研究了CO在硫修饰的铂表面的电氧化.对于溶液中的CO,其在硫修饰铂电极上的起始氧化电位最多可以比非修饰电极负移超过300 mV,而且在硫覆盖度低于0.6的条件下电位负移量随覆盖度增加而增大.这一电催化活性的增强也受溶液pH值的影响.在低硫覆盖度(小于0.3)下,吸附态的CO电氧化峰值电位比非修饰铂电极负移约40 mV.然而,在高硫覆盖度下,其峰值电位比非修饰铂电极正移近30 mV.表面增强拉曼光谱显示共吸附硫使Pt—CO振动频率显著红移.作者认为这些结果是由于吸附硫弱化Pt—CO键及阻化CO在铂表面的移动引起的.
Sulfur adsorption is generally considered to be a surface chemical reaction poison, however, a small amount of sulfur can enhance the carbon monoxide (CO) electrooxidation activity of platinum.In this paper, the electrochemical oxidation of CO on sulfur-modified platinum surface was studied by conventional electrochemical methods and surface enhanced Raman spectroscopy Oxidation.For the CO in the solution, the initial oxidation potential on the sulfur-modified platinum electrode can be negatively shifted by more than 300 mV compared with the unmodified electrode, and the negative potential shift of the potential with the coverage of sulfur below 0.6 And the increase of electrocatalytic activity is also affected by the pH value of the solution.With low sulfur coverage (less than 0.3), the peak potential of CO oxidation in the adsorbed state is negatively shifted by about 40 mV from the unmodified Pt electrode. However, at high sulfur coverage, the peak potential was approaching 30 mV as compared to the unmodified platinum electrode. Surface-enhanced Raman spectroscopy showed that co-adsorption of sulfur caused a significant redshift of the Pt-CO vibrational frequency. The authors concluded that these results are due to the adsorption of sulfur Weakened Pt-CO bond and the resistance of the movement of platinum in the platinum surface caused.