中性介质中L-丝氨酸在Pt电极上解离吸附和氧化的原位FTIR研究

运用电化学循环伏安(CV)和原位红外反射光谱(in situ FTIRS)研究了中性介质中L-丝氨酸在Pt电极上的解离吸附和氧化过程. 结果表明, 在中性溶液中, 以两性离子形式存在的丝氨酸可以在很低的电位下(-0.6 V, vs. SCE)在Pt电极表面发生解离吸附, 生成强吸物种一氧化碳(COL)、(COB)和氰负离子(CN-). 研究结果还表明, 当电位低于0.7 V(vs. SCE)时, CN-能稳定存在于电极表面, 抑制丝氨酸的进一步反应. 在更高电位时则主要为丝氨酸分子的氧化过程.

in situ FTIR Spectroscopic Studies of Adsorption and Oxidation of L-Serine on Pt Electrodes in Neutral Solutions

The dissociative adsorption and oxidation of L-serine on platinum electrode in neutral solutions were studied via in situ FTIR reflection spectroscopy and electrochemical methods. The FTIRS results demonstrate that the serine can be easily dissociated on Pt surface at potentials below -0.6 V(vs.SCE) to form cyanide(~2100 cm-1) and carbon monoxide(COL, ~2034 cm-1; COB, ~1870 cm-1). The observation of an absorption band at 2343 cm-1 is ascribed to CO2, which implies the cleavage of the C—C bond during the dissociative adsorption of serine. It has determined that the cyanide was strongly adsorbed on electrode surface in a wide potential region below 0.7 V(vs. SCE) and inhibited the oxidation of serine. At higher potentials, the serine molecules could be oxidized directly to yield the main product CO2 species. As the pH decreased in the spectroelectrochemical cell during serine reactions, the acidic serine species also detected. The present study revealed the interaction of serine with Pt electrode surface, and suggested a possible reaction mechanism of serine on Pt electrode surface in neutral solutions.