铂电极上硫化钠溶液的电化学氧化研究

研究了硫化钠水溶液在Pt电极上的电化学氧化行为 ,探讨了电势扫描速率、Na2 S溶液浓度以及表面活性剂等条件对阳极液的循环伏安谱的影响。结果表明 ,硫化钠的阳极氧化是不可逆的电极过程。阳离子表面活性剂CTAB存在时 ,电势在 -0 .65～ 0 .2 5V(vs .SCE)范围内 ,由于CTAB在电极表面上的吸附 ,阻止了电活性物种向电极表面的迁移 ,从而出现阳极电流几乎为零的平台。硫化钠溶液浓度较大时 ,阳极钝化层在电势返程扫描时被硫化物溶解而除去 ,从而出现一阳极峰。恒电流电解过程中 ,若阳极电流较低 ,则在时间 电势曲线上出现电势变化缓慢的平台 ;而电流增加时则出现电势峰 ,表明电极过程存在自催化现象 ,由此可推算出自催化过程的反应速率常数

Electrochemical Oxidation of Aqueous Na2S Solution on Pt Electrodes

Electrochemical process of aqueous Na 2S solution at Pt anodes was studied. Effects of potential scanning rates, Na 2S concentrations and surfactants on voltammograms of the anolyte were discussed. It is concluded that anodic oxidation of Na 2S solutions is an irreversible process, and in the presence of CTAB, in the potential range of -0.65 to 0.25 V(vs SCE) a plateau with nearly zero anodic current occurs. That is because the absorption layer of CTAB on the anode surface hinders the migration of electro active species to the anode. For concentrated Na 2S anolytes, passivation layer on Pt electrodes is removed during negative potential scanning, leading to an anodic peak. Choronopotentiometric curves reveal that a self catalysis is present in anodic oxidation of Na 2S solutions at Pt electrodes.