Synergetic Effect of Heterojunction and Sulfur Vacancy on ZnIn₂S₄/CeO₂ to Enhance the Photocatalytic Performance of 5‐Hydroxymethylfurfural into 2,5‐Diformylfuran

Abstract The efficient separation of photocarriers and facile generation of superoxide radicals are crucial for enhancing the performance of photocatalysts in the selectively photo‐oxidizing 5‐hydroxymethylfurfural (HMF) into 2,5‐diformylfuran (DFF). Herein, a ZnIn₂S₄/CeO₂ composite with S‐scheme heterojunction and sulfur vacancies (S_V) is successfully developed through a one‐step hydrothermal method. The optimal catalyst (S_V‐ZnIn₂S₄/CeO₂) exhibits excellent catalytic activity with 100% conversion of HMF and 96.1% selectivity of DFF in 80 min under ambient conditions, the production rate of DFF is up to 952.6 µmol g⁻¹ h⁻¹. Intriguingly, the performance remains significant even when the concentration of HMF is increased from 8 to 100 mм. Experimental and theoretical investigations discover that the synergistic effect of S‐scheme heterojunction and sulfur vacancies contribute to the separation of photocarriers and the activation of oxygen, which facilitate the generation of superoxide radicals, thus boosting the catalytic oxidation reactions.