Photoelectrochemical characteristics of electrodeposited cuprous oxide with protective over layers for hydrogen evolution reactions

Abstract

Cuprous oxide is one of the inexpensive options of highly efficient visible light-based photocathode for hydrogen generation in photoelectrochemical cells. Highly photoactive cuprous oxide (Cu2O) films are obtained by cathodic electrodeposition using lactate stabilized copper sulphate precursor exhibiting a photo-current density of ~1 mA/cm2 at −0.1 V vs. RHE. Although Cu2O is a decent choice for photoelectrochemical applications, including hydrogen evolution reaction (HER), it faces serious issues related to photodegradation and instability. To address this issue, a comparative study of two types of thin films, Al (2%)-doped ZnO (AZO) and NiOx (usually, x > 2 at low T to x→1 at high T annealing) as photo-corrosion protective overlayers is made. The improved stability of the protected photoelectrodes is observed as noted from the photocurrent degradation of 3.5%, 0.16% and 0.03% in Cu2O (bare), Cu2O/AZO, and Cu2O/NiOx photocathodes, respectively. Furthermore, the electrochemical impedance spectroscopy reveals that electrode protected with NiOx exhibit faster charge transfer kinetics and minimum photocurrent degradation as compare to the Cu2O/AZO and Cu2O(bare) photoelectrodes, proving its potential in HER kinetics.