Morallón Emilia, Arias-Pardilla Joaquín, Calo J M, Cazorla-Amorós D
Departamento de Química Física and Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99. 03080 Alicante, Spain.
Electrochim Acta. 2009 Jun 30;54(16):3996-4004. doi: 10.1016/j.electacta.2009.02.023.
The interactions of arsenic species with platinum and porous carbon electrodes were investigated with an electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry in alkaline solutions. It is shown that the redox reactions in arsenic-containing solutions, due to arsenic reduction/deposition, oxidation/desorption, and electrocatalyzed oxidation by Pt can be readily distinguished with the EQCM. This approach was used to show that the arsenic redox reactions on the carbon electrode are mechanistically similar to that on the bare Pt electrode. This could not be concluded with just classical cyclic voltammetry alone due to the obfuscation of the faradaic features by the large capacitative effects of the carbon double layer.For the porous carbon electrode, a continual mass loss was always observed during potential cycling, with or without arsenic in the solution. This was attributed to electrogasification of the carbon. The apparent mass loss per cycle was observed to decrease with increasing arsenic concentration due to a net mass increase in adsorbed arsenic per cycle that increased with arsenic concentration, offsetting the carbon mass loss. Additional carbon adsorption sites involved in arsenic species interactions are created during electrogasification, thereby augmenting the net uptake of arsenic per cycle.It is demonstrated that EQCM, and in particular the information given by the behavior of the time derivative of the mass vs. potential, or massogram, is very useful for distinguishing arsenic species interactions with carbon electrodes. It may also prove to be effective for investigating redox/adsorption/desorption behavior of other species in solution with carbon materials as well.
采用电化学石英晶体微天平（EQCM）和循环伏安法，在碱性溶液中研究了砷物种与铂电极和多孔碳电极的相互作用。结果表明，通过EQCM可以很容易地区分含砷溶液中的氧化还原反应，这些反应包括砷的还原/沉积、氧化/解吸以及铂催化的氧化反应。该方法用于表明碳电极上的砷氧化还原反应在机理上与裸铂电极上的相似。仅靠传统的循环伏安法无法得出这一结论，因为碳双层的大电容效应会模糊法拉第特征。对于多孔碳电极，在电位循环过程中，无论溶液中是否存在砷，总是观察到持续的质量损失。这归因于碳的电气化。由于每循环吸附砷的净质量增加（随砷浓度增加）抵消了碳的质量损失，观察到每循环的表观质量损失随砷浓度增加而降低。在电气化过程中会产生参与砷物种相互作用的额外碳吸附位点，从而增加每循环砷的净吸收量。结果表明，EQCM，特别是质量对电位的时间导数行为（即质量图）所提供的信息，对于区分砷物种与碳电极的相互作用非常有用。它也可能被证明对研究碳材料在溶液中其他物种的氧化还原/吸附/解吸行为有效。
