CuO photocathode enhancement through ultra-thin carbon coating layer for photoelectrochemical water splitting

In this research, we introduce a facile approach utilizing a glucose solution as a precursor to form a protective carbon layer on inherently unstable semiconductor nanostructures, addressing the pervasive issue of photo-corrosion. We focused on CuO photocathode, employing a straightforward technique to envelop them with an ultra-thin, amorphous carbon layer, rendering them suitable for photoelectrochemical (PEC) water-splitting application for hydrogen production. The results demonstrated exceptional photo-stability and significantly improved photocurrent density of CuO arrays equipped with the carbon protective layer. This transformative modification led to a substantial enhancement in PEC performance, yielding a photocurrent density up to 2.19 mA.cm⁻² at 0 V vs. RHE. Furthermore, the maximum photo-to-current conversion efficiency reached 0.12 % at 0.1 V vs. RHE under AM 1.5G illumination condition (100 mW cm⁻²). In-depth investigations revealed that these enhancements results from accelerated electrochemical charge transfer at the electrode/electrolyte interface and concurrent mitigation of photo-corrosion rates. This approach has the potential to address stability concerns among a broad range of non-stable photoelectrodes, offering significant contributions to the field of energy conversion and the advancement of renewable energy technologies.