关键词: 次磷酸盐, 氧化, 循环伏安法

Abstract: There exist two oxidation current peaks on the anodic polarization curve between -0.7 V and 0 V(SCE) in Na_hypophosphite solution. Peak Ⅰ (-0.55 V, SCE) , which represents the oxidation process from H 2PO - 2 to H 2PO - 3, has been studied previously. Peak Ⅱ, which is located at the potential about -0.4 V(SCE), is investigated emphatically in this paper. The results show that, peak Ⅰ and Ⅱ are corresponding to two successive steps in oxidation process of H 2PO - 2, i.e. peak Ⅱ corresponds to the oxidation process of adsorped (HPO 2) ads , an intermediate product of electrode reaction of peak Ⅰ, to PO 3- 4. The rate limiting step in the electrode process from (HPO 2) ads to HPO 2- 3 is the desorption of (HPO 2) ads , and the desorption rate constant is estimated as 2.32±0.20 s -1 . A new schematic of oxidation process of hypophosphite is proposed.