Self-confined oxidation domains in dual-metal sulfide catalyst enables active sites for selective photoconversion of carbon dioxide to methanol by pure water

The selective photoreduction of carbon dioxide (CO₂) into high-value products, such as methanol, is a highly desirable yet challenging research area. Herein, we report a facile hydro-solvothermal-assisted method (HSM) for constructing dual-metal-site (Sn, In)-based photocatalysts. The resulting composites function as synergistic catalysts, achieving nearly 100 % selectivity for methanol in pure water under an AM1.5 G solar simulator. The formation of a highly stable Sn–C–O–In configuration within the dual-metal-site catalyst (SnIn₄S₈) facilitates the promotion of key intermediates (*COOH/*CHO) essential for the selective photoreduction of CO₂ to methanol following protonation. Additionally, the oxidation domains confined on the SnIn₄S₈ surface can be self-regulated by adjusting the water to ethylene glycol ratio during the HSM process. Experimental and theoretical results indicate that these oxidation domains not only favor the methanol production pathway but also enhance CO₂ adsorption and activation, as well as charge separation and transport. Consequently, the photoreduction efficiency of CO₂ is boosted, achieving rates twenty times higher than those of prismatic SnIn₄S₈. This work provides valuable insights into the role of oxidation domains confined within dual-metal sulfides in CO₂ photoreduction, paving the way for higher CO₂ reduction efficiency while maintaining the selectivity of the parent catalyst.