Mechanism of MoO2 electrodeposition from ammonium molybdate solution

从钼酸铵溶液中电沉积MoO2的机理（英文）

A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.

采用线性扫描伏安曲线、物种分配图、拉曼光谱、傅里叶红外光谱、X射线衍射等手段研究从酸性和碱性体系中电沉积MoO2的机理。结果表明,钼酸铵电解液中主要存在两种可被还原的物种,即Mo7O24^6-和钼铵络合物。在不含NH4^+的弱酸性体系中,主要物种为Mo7O24^6-,其还原为Mo(Ⅳ)氧化物的峰电位约为-0.7 V(vs SCE);在不含NH4^+的中性和碱性体系中,主要物种为MoO4^2-,此时扫描伏安曲线中无还原峰出现,仅发生析氢反应;电解体系中加入NH4^+对MoO2电沉积产生重要影响,酸性或碱性条件下均在-1.25 V(vs SCE)处出现一个新的还原峰,对应于钼铵络合物的还原。本文作者系统地研究电解液组分和电沉积条件的影响。通过优化电沉积条件,电流效率达到51.9%。