First evidence of the oxidation and regeneration of polysulfides at a GaAs electrode, under anodic conditions. A study by in situ UV-visible spectroelectrochemistry
First evidence of the oxidation and regeneration of polysulfides at a GaAs electrode, under anodic conditions. A study by in situ UV-visible spectroelectrochemistry
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DOI：
10.1021/jp046977y
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发表时间：
2004-11-25
影响因子：
3.3
通讯作者：
Sauvage, FX
中科院分区：
文献类型：
--
作者：
Debiemme-Chouvy, C;Wartelle, C;Sauvage, FX
我们报道了 (NH4)(2)S-n 水溶液中多硫化物在 GaAs 电极上的氧化和再生。多硫化物离子的浓度可以通过光学吸收光谱来监测。因此，在阳极电位下，在“GaAs/(NH4)(2)S-n 溶液”界面处的浓度变化，通过在薄层条件下和恒电流模式下进行的原位紫外-可见光谱电化学来进行跟踪。在这些条件下，界面处溶液吸收的变化一方面使我们能够确认多硫化物在GaAs电极上被氧化，导致S Degrees的释放，另一方面，强调S Degrees与HS-离子反应以恢复多硫化物。此外，研究表明，1% (NH4)(2)S-n 水溶液中存在的主要多硫化物物种是五硫离子 S-5(2-)。最后，这项工作表明，在阳极电流和电解质成分一定的条件下，GaAs阳极的表面既不被氧化，也不被钝化。
We report on the oxidation and regeneration, at a GaAs electrode, of polysulfides present in (NH4)(2)S-n aqueous solutions. The concentration of the polysulfide ions can be monitored by optical absorption spectroscopy. Thus, the variation of their concentration at a "GaAs/(NH4)(2)S-n solution" interface, under anodic potential, was followed by in situ UV-visible spectroelectrochernistry performed in thin layer conditions and in g-alvanostatic mode. Under these conditions, the variation of the solution absorption at the interface allowed us, on one hand, to confirm that the polysulfides are oxidized at a GaAs electrode, leading to the release of Sdegrees, and, on the other hand, to underscore that Sdegrees reacts with HS- ions to restore polysulfides. Moreover, it was shown that the main polysulfide species present in a 1% (NH4)(2)S-n aqueous solution is the pentasulfide ion, S-5(2-). Finally, this work shows that under definite conditions of anodic current and electrolyte composition, the surface of the GaAs anode is neither oxidized nor passivated.