Efficient WO₃ Nanoplate Arrays Photoanode Modified by ZnO Nanosheets for Enhanced Charge Separation and Transfer to Promote Photoelectrochemical Performances

A key factor in the photoelectrochemical (PEC) performance of photoelectrodes is the efficient separation and transfer of photogenerated charges. Herein, a novel photoanode comprising three-dimensional (3D) WO3 nanoplate@ZnO nanosheet hierarchical type-II heterojunction arrays (3D WO3@ZnO HHAs) is designed and constructed via modification of the WO3 nanoplate arrays with ZnO nanosheets. The synthesized materials are characterized viaX-ray diffraction (XRD), ultraviolet and visible spectrophotometry (UV-vis), scanning electon microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. Photoelectrochemical (PEC) test results reveal that the synthesized 3D WO3@ZnO HHAs photoanode exhibits reduced charge transfer resistance, improved electron-hole pair life, and enhanced photocurrent density (approximate to 4.5 times increase in comparison to that of the bare WO3). The increased light capture and high surface area in contact with the electrolyte as well as the enhanced charge transfer through the synergy between morphology and band structures may be responsible for the improved PEC characteristics.