The primary objective of this study is to synthesize and examine a highly effi cient photo-catalyst endowed with robust

and sustained photo-catalytic capabilities, with a particular focus on its applicability within photoelectrochemical (PEC)

processes. The methodology employed involves the hydrothermal synthesis of CuO, subsequently subjected to a spincoating

process for the deposition of ZnBi 2 O 4 (ZBO) across a multi-layer, followed by high-temperature annealing for

structure optimization. A comprehensive suite of analyses encompassing morphological, structural, textual, optical, and

PEC measurements was conducted on the synthesized samples. Experimental fi ndings underscore the notable enhancement

in photo-catalytic performance achieved through the formation of heterojunction, particularly conductive to facilitating the

PEC hydrogen evolution reaction (HER) process when juxtaposed with the individual constituents (CuO and ZBO). Among

these samples, CuO/ZBO-10 exhibited commendable photo-stability and demonstrated remarkable visible-light-induced

photo-catalytic effi ciency in driving the PEC HER process. The integration of ZBO coatings notably augments the PEC

performance of CuO, with the CuO/ZBO-10 photocathode attaining a photo-current density of up to -1.35 mA.cm −2 at 0 V

vs. RHE, under standard test conditions. Importantly, the CuO/ZBO-10 photocathode exhibits superior retention of optical

activity, with 63.11% maintained after 3600 s of irradiation, signifi cantly surpassing the performance of bare CuO (10.98%).

A detailed examination of the experimental data elucidates that the observed enhancements in photo-current density and

stability can be attributed to the facilitated electrochemical charge transfer at the electrode/electrolyte interface and the

concomitant mitigation of photo-corrosion rates.