Photoelectrochemical hydrogen generation employing a Cu2O-based photocathode with improved stability and activity by using NixPy as the cocatalyst

Abstract

With the tactical integration of band edge energetics concepts in semiconducting films to reduce charge recombination and photocorrosion, an improvement in the photocurrent can be achieved by introducing CuO and Ni_xP_y into Cu₂O films. Photodegradation limitations of Cu₂O are overcome by the Cu₂O–CuO–Ni_xP_y photocathode. Ni_xP_y, because of its excellent electrocatalytic hydrogen evolution activity, helps in obtaining better stability and activity. The individual effects of CuO and Ni_xP_y have been investigated and it is found that the activity enhancement stems mainly from the contribution of Ni_xP_y, whereas CuO helps with the unidirectional flow of photogenerated charges to prevent the photocorrosion of Cu₂O. Relative to bare and modified Cu₂O, Cu₂O–CuO–Ni_xP_y shows a considerable reduction in the overpotential and a remarkable improvement in the photocurrent at 0 V (vs. RHE). This is the first report on the use of Ni_xP_y as the co-catalyst in a Cu₂O based photocathode system to improve its photostability as well as its activity.