应用循环伏安、方波伏安和交流阻抗法研究了Keggin型缺位硅钨杂多阴离子SiW11O398-(SiW11)在0.1mol?L-1 NaHSO4 + Na2SO4溶液中的电化学性质及其对H2O2还原的间接电催化作用。结果表明，SiW11的酸性水溶液在玻碳(GC)电极上显示两对可逆的还原-氧化波，对应的电荷迁移数均为1，且有2个质子参与反应。根据第1对波的还原峰电流与扫描速率平方根关系得到SiW11在溶液中的扩散系数Do为8.92×10-6 cm2?s-1。SiW11对H2O2的还原具有明显的电催化活性，催化峰电位随溶液pH的降低而正移，峰电流增大。质子H+在催化反应中起协同促进作用。实验测定该电催化过程的均相准一级反应速率常数为0.30 s-1。SiW11电催化还原H2O2的机理被认为该反应是经过形成所谓“七配位过氧化物”而发生的。
刘希龙
,
吴春燕
,
周方
,
刘红生
,
华英杰
,
王崇太
,
刘晓旸
. Keggin型缺位硅钨杂多阴离子的电化学性质及电催化还原H2O2[J]. 电化学, 2012
, 18(2)
: 174
-180
.
DOI: 10.61558/2993-074X.2900
Electrochemical properties of the Keggin-type lacunary heteropolysilicate anion SiW11O398- (SiW11) and its indirect electrocatalysis for H2O2 reduction in the supporting electrolyte containing 0.1 mol?L-1 NaHSO4 and Na2SO4 solutions were investigated using cyclic voltammetry, square wave voltammetry and alternating current impedance spectroscopy. Experimental results indicated that SiW11 showed two pairs of reversible redox waves on the glassy carbon (GC) electrode in an acidic solution. The electron transfer number corresponding to the two pairs of waves was one, and the proton transfer number involved was two during the electrode reaction. The diffusion coefficient (D0) of SiW11 calculated from the linear relationship of peak current versus square root of potential scan rate was determined to be 8.92×10-6 cm2?s-1 in 0.1 mol?L-1 NaHSO4 and Na2SO4 solutions. The SiW11 displayed an obvious electrocatalytic activity for the H2O2 reduction. The electrocatalytic peak potential moved to positive direction with the decrease in the solution pH, and the peak current increased. The electrocatalytic process was facilitated by proton through a synergic effect. The pseudo-first order rate constant of the homogeneous reaction was determined to be 0.30 s-1. The indirect electrocatalytic process of SiW11 towards H2O2 reduction was considered to take place through a mechanism involved in a so-call “the seven-coordinate W-O peroxo species”.
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