Photostability improvement by the suppression of photocorrosion with a NiOx capping layer on CuO photoelectrodes

Abstract

An increase in the photocurrent density and photostability of CuO photoelectrodes is important for the efficient photoactivity of the CuO photoelectrodes in photoelectrochemical cells. Herein, a NiOx capping layer was deposited on a CuO photoelectrode to act not only as a protective layer but also as a co-catalyst to reduce the photocorrosion that causes the low photostability of CuO photoelectrodes. It was found that CuO photoelectrode photocorrosion was reduced by controlling the NiOx deposition time and the NiOx precursor concentration. As the NiOx capping layer deposition time or NiOx precursor concentration increased, the NiOx capping layer completely covered the surface of the CuO photoelectrode and improved the crystallinity of the NiOx/CuO heterojunction photoelectrode. The photoelectrochemical properties of the NiOx/CuO heterojunction photoelectrode were improved with the help of the NiOx capping layer. As a result, an improved photocurrent density and photostability were obtained with a NiOx capping layer that was deposited for 10 min and with a NiOx precursor concentration of 25 mM. The photostability was particularly improved to 71.9%, which is approximately 3 times higher than the 22.7% of the single CuO photoelectrode.