Crystal face dependence of p-Cu2O stability as photocathode

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Previously we hypothesized that the reported stability of electrodeposited p-Cu O films is attributed to the predominant Cu - terminated (111) surface, where the Cu -supported O reduction occurs and the H -assisted Cu O reduction, which is the decomposition of Cu O, does not happen. The well-known instability of single-crystal Cu O is attributed to predominant (211) and (311) surfaces, where the photodecomposition into Cu is inevitable at the exposed O sites. To examine our hypothesis, the stability and photochemical behavior were compared between electrodeposited Cu O films with predominantly Cu -terminated surfaces and ones with predominantly O -terminated surfaces. When used as photocathodes, the predominantly Cu -terminated films did not deteriorate as readily as the predominantly O -terminated films did. Also, when oxygen was removed from the aqueous solution, the predominantly Cu -terminated films generated photocurrents one order of magnitude smaller compared to the predominantly O -terminated films, indicating the stability of the Cu -terminated surface against photodecomposition into Cu. These results confirmed our hypothesis on the crystal face dependence of p-Cu O stability as a photocathode. © 2009 The Electrochemical Society. 2 + 2 2 2 2 2 2 + + 2- + 2- + 2- + 2- +

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Journal of the Electrochemical Society

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