MgCr<sub>2</sub>O<sub>4</sub>/MgIn<sub>2</sub>S<sub>4</sub> Spinel/Spinel\nS‑Scheme Heterojunction: A Robust Catalyst\nfor Photothermal-Assisted Photocatalytic CO<sub>2</sub> Reduction

Photocatalytic\nCO<sub>2</sub> reduction technology has engaged\nsignificant attention due to its high efficiency, high selectivity,\nand environmental friendliness. However, its application is severely\nrestrained by issues such as low separation efficiency of photogenerated\ncarriers and a limited light absorption range. This work proposes\nan innovative MgCr<sub>2</sub>O<sub>4</sub>/MgIn<sub>2</sub>S<sub>4</sub> magnesium-based spinel/spinel heterostructure photocatalyst\nto improve the photocatalytic CO<sub>2</sub> reduction efficiency\nthrough the synergistic contributions of S-scheme heterojunction and\nphotothermal effect. On the one hand, the unique S-scheme charge transfer\nmechanism enables the effective separation of photogenerated carriers.\nOn the other hand, the photothermal effect allows an accelerated charge\nmigration by increasing the reaction center temperature. Moreover,\nthe abundant oxygen vacancies serve as electron traps and CO<sub>2</sub> adsorption sites, unifying reaction and adsorption sites and substantially\nimproving catalytic efficiency. Under UV–vis and UV–vis-NIR\nillumination, the average CO yields of the MgCr<sub>2</sub>O<sub>4</sub>/MgIn<sub>2</sub>S<sub>4</sub> composite are 8.03 and 15.62 μmol\ng<sup>–1</sup> h<sup>–1</sup>, respectively, greatly\nhigher than those of pure MgCr<sub>2</sub>O<sub>4</sub> and MgIn<sub>2</sub>S<sub>4</sub> samples. Furthermore, the fabricated photocatalyst\ndemonstrates excellent performance and structure stability. Therefore,\nthis work may offer a new strategy for designing efficient and stable\nphotocatalysts.