对氯苯酚电氧化过程中Pt电极的失活机制

利用线性伏安法、LC/MS和光谱技术研究了Pt电极在电化学氧化降解对氯苯酚过程中的失活现象.结果表明,由于电极表面的聚合反应, Pt电极会在短时间内失活.现场红外分析表明,电氧化过程中Pt电极在1200cm-1和1800cm-1,处分别出现了芳醚和羰基的特征吸收峰.提高对氯苯酚初始浓度和溶液pH均会加快电极的失活速率.对失活Pt电极的乙腈浸洗液进行LC/MS分析表明,电极表面形成的聚合物并不是具有单一结构的化合物,而是一些混合物,其形成的机理主要包括自由基之间的相互偶合、自由基与底物、中间产物或低聚物的取代反应等方式.

Deactivation Mechanism of Pt Anode in the Process of Electroxidation of p-Chlorophenol

Deactivation of Pt electrode in the process of electroxidation of p-chlorophenol (p-CP) was investigated using linear sweep voltammetry, LC/MS and spectrum analysis techniques. The experiment results indicated that Pt would lose its electro-catalytic activity soon because polymer formed at the electrode surface. The in-site IR spectra of Pt showed two weak absorption bands appeared at 1 200 and 1 800 cm^-1 during the oxidation of p-CP, which are characteristics of aromatic ether and carbonyl group, respectively. Increasing initial concentration of p-CP and pH value of solution would accelerate the deactivation speed of Pt. Acetonitrile lixivium for deactivated Pt was analyzed by LC/MS, and it was found that the polymers formed at the surface of Pt were some mixed compounds. The mechanism of polymerization includes the following ways: coupling reaction of organic radical each other; substituting reaction of organic radical with p-CP (or intermediates or small polymers).