Tuning the morphology of ZnCdS@CeO2 Z-scheme heterostructures from core–shell to core–satellite for superior photocatalytic performance

Abstract

In addition to solar cells, photocatalysis is an alternative way for the direct utilization of clean and sustainable solar energy. Currently, the core challenge in photocatalysis is the efficiency of the separation and transfer of the photogenerated electrons (e⁻) and holes (h⁺) in photocatalysts. Herein, continuous tuning of ZnCdS–CeO₂ heterostructures via a seed-mediated growth approach yielded two typical hybrid structures: ZnCdS–CeO₂ core–satellite (ZCSC I) and ZnCdS@CeO₂ core–shell (ZCSC II). Leveraging the Janus configuration of the ZCSC I structure, a marked improvement in charge separation and transfer efficiency was observed in photocurrent and transient fluorescence tests. This enhancement should be due to the electron “sink effect” in the ZCSC I structure, as well as the spatial separation of the ZnCdS (ZCS) and CeO₂ domains. Furthermore, the photocatalytic activity of the heterostructures was evaluated using the photocatalytic degradation of methylene blue (MB) as a model reaction. Consistent with the above tests, the ZCSC I structure showed the highest MB degradation rate of 91% within 60 minutes. From the calculated kinetic rate constants (k values), the k value of the ZCSC I structure is 4, 2.1, and 1.5 times higher than those of the CeO₂, ZCS, and ZCSC II structures, respectively. Through radical trapping experiments, the ZnCdS–CeO₂ heterostructures were identified as Z-scheme heterojunctions. This work provides solid mechanistic understanding and valuable insights for improving the catalytic efficiency of hybrid photocatalysts, which is helpful for the rational design and precise control of hybrid photocatalysts with high catalytic efficiency and would assist their applications in diverse catalytic reactions.