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

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 similar to 1 mA/cm(2) 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 photo degradation 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. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study demonstrates that covering the surface of cuprous oxide with Al (2%)-doped ZnO (AZO) or NiOx films can effectively improve the stability of photoelectrodes and reduce photocurrent degradation. Among them, NiOx overlayers can accelerate charge transfer kinetics and exhibit the minimum photocurrent degradation, showing potential in hydrogen evolution reaction kinetics.