Communication - The reduction of selenate mediated by underpotential deposited copper on gold electrodes in acidic solutions: Analytical applications

Voltammetric techniques have been employed to show that underpotential deposited Cu on polycrystalline Au electrodes in aqueous 0.1 M HClO₄ catalyzes the reduction of purified selenate, SeO₄ ^2-, to yield a layer of adsorbed copper selenide, Cu_xSe. Subsequent oxidation of this layer led to the loss of Cu, leaving behind adsorbed, elemental Se, which could be oxidized to selenite, SeO₃ ^2-, at higher potentials. Application of this method made it possible to detect SeO₄ ^2- down to nM levels. Voltammetric features observed on Au(poly) in Cu²⁺-free 0.1 M HClO₄ containing SeO₄ ^2- reported earlier in the literature could be attributed to the reduction of SeO₃ ^2- impurities present in the commercial chemical.