Pt quantum dots embedded at the base of vertically aligned ZnO nanowire arrays for enhanced carrier separation and light trapping

Abstract

Semiconductor photocatalysis holds great promise for energy conversion and environmental remediation, but its efficiency is often limited by the rapid recombination of photogenerated carriers. To overcome this issue, we engineered a ZnO nanowire photoanode by embedding platinum quantum dots (Pt QDs) at the base of the nanowires between the fluorine-doped tin oxide (FTO) substrate and the ZnO layer. Unlike conventional surface-decoration approaches, the photoanode's ability to collect photogenerated carriers is enhanced due to the excellent electrical conductivity of Pt, facilitating efficient separation and transfer of photogenerated electrons. Additionally, the introduction of Pt QDs increases the roughness of the FTO substrate, resulting in a vertically uneven ZnO nanowire morphology that enhances light scattering and absorption. The optimized ZnO/Pt QDs photoanode exhibited a significantly improved photocurrent density of 0.23 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE), representing a 35.3% enhancement over pristine ZnO. This dual-function design provides a promising strategy for developing high-performance photoanodes for photocatalytic applications.