Morphological‐dependent charge transfer at <scp> WO ₃ </scp> / <scp> BiVO ₄ </scp> heterojunction for photoelectrochemical application

Abstract This study investigates the morphological‐dependent photoelectrochemical (PEC) performance of WO 3 /BiVO 4 composite photoanodes with nanoparticle (NP), nanosheet (NS), and nanorod (NR) structures. Structural characterization revealed that NS and NR WO 3 exhibit well‐defined morphologies and high crystallinity, while NP WO 3 appears irregular. PEC measurements showed that the NS WO 3 /BiVO 4 photoanode achieved the highest photocurrent density and charge transfer efficiency, attributed to enhanced light absorption, efficient charge separation, and improved charge transport. Electrochemical impedance spectroscopy confirmed the lowest interfacial resistance and longest charge carrier lifetime of 4.26 ms for the NS structure. Ultraviolet photoelectron spectroscopy revealed a Type‐II band alignment in WO 3 /BiVO 4 heterojunctions, facilitating charge transfer. The superior performance of NS WO 3 /BiVO 4 highlights the importance of morphology engineering in optimizing PEC water oxidation efficiency, making it a promising candidate for sustainable hydrogen production.