Surface-selective growth of noble-metal-free nanodumbbells photocatalyst with spatially separated redox sites using in-situ ion exchange for simultaneous microplastics upcycling and H2 evolution

Abstract

Solar-driven photocatalytic upcycling of harmful microplastics (MPs) coupled with H2 production is a promising avenue to alleviate global environmental and energy issues. However, developing stable and cost-effective photocatalysts with efficient carrier separation remains a considerable challenge. Herein, based on surface-selective growth followed by in-situ ion exchange method, MoS2 and Cu2S are selectively grown on the tips and sidewalls of CdS nanorods to construct precious-metal-free ternary MoS2-CdS/Cu2S heterojunction nanodumbbells, featuring orderly and spatially separated redox sites. In the nanoarchitecture, site-specific MoS2 and Cu2S serve as electron and hole collectors, respectively, to decouple the collection direction of photogenerated carriers, achieving the spatial separation of redox half-reaction and strong photostability of nanodumbbells. Additionally, the heterojunctions (Schottky junction of MoS2-CdS and p-n junction of CdS/Cu2S) allow the charge to quickly flow in selective directions, resulting in an efficient separation rate of photogenerated excitons. With the joint action of spatially separated redox sites and ternary heterojunction, MoS2-CdS/Cu2S achieves an effective conversion of MPs into acetic acid (acetic acid concentration of 2870.0 µg·L-1 within 20 h) along with H2 evolution (305.0 µmol·g-1 within 4 h) without any sacrificial reagents.