MgCr2O4/MgIn2S4 Spinel/Spinel S-Scheme Heterojunction: A Robust Catalyst for Photothermal-Assisted Photocatalytic CO2 Reduction

Photocatalytic CO₂ reduction technology has engaged significant attention due to its high efficiency, high selectivity, and environmental friendliness. However, its application is severely restrained by issues such as low separation efficiency of photogenerated carriers and a limited light absorption range. This work proposes an innovative MgCr₂O₄/MgIn₂S₄ magnesium-based spinel/spinel heterostructure photocatalyst to improve the photocatalytic CO₂ reduction efficiency through the synergistic contributions of S-scheme heterojunction and photothermal effect. On the one hand, the unique S-scheme charge transfer mechanism enables the effective separation of photogenerated carriers. On the other hand, the photothermal effect allows an accelerated charge migration by increasing the reaction center temperature. Moreover, the abundant oxygen vacancies serve as electron traps and CO₂ adsorption sites, unifying reaction and adsorption sites and substantially improving catalytic efficiency. Under UV-vis and UV-vis-NIR illumination, the average CO yields of the MgCr₂O₄/MgIn₂S₄ composite are 8.03 and 15.62 μmol g^-1 h^-1, respectively, greatly higher than those of pure MgCr₂O₄ and MgIn₂S₄ samples. Furthermore, the fabricated photocatalyst demonstrates excellent performance and structure stability. Therefore, this work may offer a new strategy for designing efficient and stable photocatalysts.