Morphology-Controlled ZnO@ZnWO₄ Hetero-Nanostructures for Efficient Photooxidation of Water in Near-Neutral pH

One-dimensional ZnO nanorods (NRs) have been extensively studied as photoanodes because of their unique optical properties, high electron mobility, and suitable band positions for water oxidation. However, their practical efficiency is often compromised by chemical instability during water oxidation and high carrier recombination rates. To overcome this issue, precise morphological control of ZnO@ZnWO₄ core-shell structured photoanodes, featuring a ZnO core and a ZnWO₄ shell was used. This was accomplished by depositing WO₃ onto hydrothermally grown ZnO NRs using the thermal chemical vapor deposition process. The photoelectrochemical performance of ZnO@ZnWO₄ with an optimized morphology outperforms that of pristine ZnO NRs. Systematic optical and electrochemical analyses of ZnO@ZnWO₄ demonstrated that the enhancement is attributed to the enhanced charge transfer efficiency facilitated by the optimized ZnWO₄ shells.