原位红外光谱法研究对氯苯酚在Pt电极上的电氧化行为

In-situ FTIR Studies on Electrooxidation of p-Chlorophenol on Pt Electrode

采用原位红外光谱法研究了碱性条件下对氯苯酚(PCP)在Pt电极上电化学氧化的脱氯反应机理.研究结果表明Pt电极对PCP有良好的电化学反应活性,其氧化过程首先是对氯苯酚负离子氧化生成对氯苯氧自由基,该自由基可与对氯苯酚负离子作用生成芳香醚低聚物;随着电位升高,对氯苯酚负离子经电化学氧化生成了苯二酚盐(还可能存在其氧化产物不饱和羧酸盐);当电位继续升高,苯二酚盐进一步氧化形成苯醌;最后,在Pt表面生成小分子羧酸盐,同时生成了最终产物CO2.但由于芳香醚低聚物等不溶性聚合物膜的形成并吸附在Pt电极表面,可造成Pt电极毒化,使得Pt电极在使用过程中逐渐失去活性.

Electrochemical oxidation of p-chlorophenol （PCP） on a Pt electrode in alkaline solution has been investigated using in situ FTIR technique. Results showed that the Pt electrode exhibited a good performance for the electrooxidation of PCP. Firstly, p-chlorophenol anion on the surface of Pt electrode was electrooxidized to p-chlorophenolic radical, which reacted with p-chlorophenol anion to generate insoluble aromatic ether oligomer. With the increase of potential, p-chlorophenol anion was transformed to dihy- droxybenzene （maybe with unsaturated carboxylic acids）. Then, the dihydroxybenzene could be electrooxidized to benzoquinone at more positive potential. Finally some light weight carboxylate and ultimate product CO2 were achieved. But the Pt electrode could be poisoned with formation of the insoluble oligomer on its surface, and may lose its electrochemical activity gradually.