Engineering of sulfur defects in ZnIn ₂ S ₄ via pulsed laser ablation for enhanced photocatalytic CO ₂ reduction performance

Abstract Vacancy defect engineering represents one of the most effective strategies for enhancing photocatalytic performance. However, the wide applications of vacancy defect engineering are confronted with the problems of lack of precise control over vacancy defect engineering and poor stability. Herein, we employed an advanced pulse laser ablation in liquid (PLAL) method to introduce sulfur vacancies on the ZnIn2S4 nanosheets. Specifically, the vacancy concentration on the ZnIn2S4 can be easily modulated by changing the time for PLAL. In addition, it is discovered that the introduction of sulfur vacancies on the ZnIn2S4 nanosheets can provide enormous surface-active sites and facilitate the photogenerated charge carrier, thereby enhancing the photocatalytic CO2 conversion. Compared to the pristine ZnIn2S4, the sulfur vacancies-rich ZnIn2S4 nanosheets show 15-fold enhancement in photocatalytic CO2 conversion performance towards CO production, reaching 365 µmol·g−1·h−1. In addition, the sulfur vacancy-rich ZnIn2S4 shows a high stability for photocatalytic CO2 conversion, retaining its performance after 12 h of reaction. According to the mechanistic studies, it is revealed that the sulfur vacancies can also enhance the adsorption capability of ZnIn2S4, thereby reducing the potential barrier for subsequent conversion. This work demonstrates the potential of the PLAL strategy for not only precisely introducing vacancy defects on the semiconductors, but also enhancing the stability of the defects, which can pave new avenues for the photocatalytic applications.