In-situ IR Spectroscopic Study of Oxidation of NaH_2PO_2 on Pt Electrodes in Acidic Solutions
- 化学化工－已发表论文 
用 SNIFTIRS和循环伏安法研究酸性溶液中次亚磷酸钠在多晶铂电极上的电氧化机理 .分析了 0 .5mol/ L H2 SO4+ 0 .1 mol/ L Na H2 PO2 溶液中原位红外反射谱图与电极电位的关系 ,发现在发生反应的电位下Pt电极上的吸附物种有氢原子和 H2 PO2 ,最终的氧化产物是 H3 PO4而不是 H2 PO- 3 ,据此提出了酸性介质中次亚磷酸根离子在 Pt上氧化的新机理 .The mechanism of electrochemical oxidation of hypophosphite on a polycrystalline platinum electrode was studied by SNIFTIRS (i.e. Subtractively Normalized Interfacial FTIR Spectroscopy) as well as by cyclic voltammetry. The in-situ IR reflectance spectra were analyzed as a function of the Pt electrode potentials in 0.5 mol/L H 2SO 4 +0.1 mol/L NaH 2PO 2 solution. The in-situ IR band characteristics are those near 2 100, 1 250 and 1 110 cm -1, assigned as the presence of adsorbed hydrogen atom on Pt and non-adsorbed H 3PO 4 molecule or phosphate species, respectively. It was concluded that both hydrogen atoms and H 2PO 2 are the adsorbed species on Pt in the potential range where the oxidation occurs, and the final oxidation product was H 3PO 4 rather than phosphate, different from the oxidation of hypophosphite on Ni electrode. Accordingly, a new mechanism was proposed for the hypophosphite oxidation on Pt electrodes in acidic media, i.e. in the potential range lower than 0.8 V(vs. SCE) the adsorbed H 2PO 2 was directly oxidized to phosphate via phosphite, and in the potential range higher than 0.8 V the oxygen-adsorbed species on Pt participates in the oxidation of H 2PO 2 into phosphate.