Abstract Copper bismuthate (CuBi 2 O 4 ) is a visible-light-responsive p -type semiconductor with significant potential for photoelectrochemical solar energy conversion, although its performance is limited by rapid charge recombination and poor interfacial charge transfer. In this work, a BiVO 4 /CuBi 2 O 4 p–n heterojunction photocathode was fabricated via electrodeposition on FTO conductive substrates to enhance interfacial charge separation and transport. XRD and Raman analyses confirmed the coexistence of BiVO 4 and CuBi 2 O 4 crystalline phases, while SEM and EDS revealed the morphology and homogeneous elemental distribution of the heterostructure. In an inert electrolyte, photoelectrochemical measurements revealed a significant enhancement in cathodic photocurrent density (− 121 µA cm⁻²) compared to pristine CuBi 2 O 4 (− 78 µA cm⁻²), accompanied by reduced charge-transfer resistance and improved interfacial kinetics, as evidenced by electrochemical impedance spectroscopy. Furthermore, the heterojunction exhibited a prolonged charge-carrier lifetime (36 s), indicating suppressed electron–hole recombination. These results are attributed to the formation of a type II band alignment at the BiVO 4 /CuBi 2 O 4 interface, which promotes efficient spatial separation of charge carriers. This study demonstrates that electrodeposited BiVO 4 /CuBi 2 O 4 heterojunctions are a promising strategy to enhance photocathode performance for solar energy conversion.
Meneses et al. (Fri,) studied this question.