Popcorn-like ZnCdS-based nanospheres with hierarchical tandem heterojunctions synergy for efficient photocatalytic performance

Abstract

Heterojunction engineering is widely recognized as one of the most effective strategies for enhancing photocatalytic performance and suppressing photocorrosion by promoting efficient carrier separation and transfer. In this work, popcorn-like ZnCdS-MoS2@Co3O4 nanospheres with large specific surface areas and hierarchical tandem heterojunctions were synthesized via one-pot in-situ self-assembly combined with hole-driven photodeposition. Based on the highly uniform dispersion of MoS2 as an electron collector in the system and precise deposition of Co3O4 as a photogenerated hole collector driven by photogenerated carriers at the hole enrichment position, it can efficiently catalyze the photocatalytic hydrogen evolution in water. Compared to ZnCdS, the optimized ZCS-M@0.5C exhibits a 50-fold increase in visible-light-driven hydrogen evolution efficiency, achieving 18.73 mmol·h−1·g−1 and maintaining stability after a 20-hour cycle test. Additionally, the apparent quantum yield reaches a remarkable 10.11% at 420 nm. Experimental characterization tests and differential charge density analysis have confirmed the efficient ability of Pt-like MoS2 to induce electron separation and transportation, while p-type semiconductor Co3O4 accumulates holes through the p-n junction. Both theoretical and experimental evidence show that the incorporation of dual-internal electric fields facilitates bi-directional charge separation and rapid transfer. The photocatalytic performance is improved through a synergistic effect involving hierarchical tandem heterojunctions. This work presents a novel approach to fabricating highly efficient photocatalysts with multi-heterojunctions through synergistic effects.