Abstract
An Al2O3 capping layer was grown on a CuO photoelectrode using microwave-chemical bath deposition. We investigated the effects of the concentration of the Al2O3 precursor solution on the morphological, structural, optical, electrical and photoelectrochemical properties of the Al2O3/CuO heterostructure photoelectrode. XPS analysis confirmed that the CuO was structurally stabilized by the Al2O3 capping layer. In addition, we found that the morphology, (020) XRD peak intensity, (020) XRD peak full width at half maximum, optical energy band gap, flat-band potential and acceptor density values of the Al2O3/CuO heterostructure photoelectrode were strongly dependent on the concentration of the Al2O3 precursor solution. Among the photoelectrodes evaluated in this study, the Al2O3/CuO heterostructure photoelectrode obtained with an Al2O3 precursor concentration of 3mM had the highest crystallinity, flat-band potential and acceptor density. It also exhibited a photocurrent density of -2.64mA/cm2 (vs. SCE at −0.55V) and a photostability of approximately 55%. In contrast, bare CuO had a photocurrent density of −1.8mA/cm2 (vs. SCE at −0.55V) and a photostability of 25%. Based on our results, the photocurrent density and photostability of the CuO photoelectrode could be dramatically improved by capping with an Al2O3 layer using a 3mM precursor concentration.
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