Black In₂O_3−x nanosheets for efficient solar-driven reverse water-gas shift reaction

Increasing the number of surface-active sites and light-harvesting capability of catalysts by regulating their electronic structures is critical for solar-driven reactions. Herein, we report an oxygen-defective rich catalyst, black In₂O_3−x nanosheets, as efficient catalysts for solar-driven CO₂ hydrogenation reaction. The efficiency of CO₂ hydrogenation can be enhanced through the combination of interband transition and active sites oxygen vacancies, coupled with exceptional photothermal conversion that rapidly elevates the catalyst surface temperature to 299 °C. Experimental results and characterization analyses reveal that the introduction of oxygen vacancies not only furnishes abundant adsorption and activation sites for CO₂ but also extends the light absorption range of In₂O_3−x and improves the photothermal conversion efficiency. Black In₂O_3−x nanosheets with oxygen-rich defects exhibit remarkable solar-driven catalytic performance in the reverse water-gas shift (RWGS) reaction, achieving a CO generation rate as high as 69.8 mmol·h⁻¹·m⁻² with a selectivity approaching 100%. This study demonstrates that structural engineering of In₂O₃ nanosheets via a mild room temperature lithium reduction strategy significantly enhances catalytic activity, a methodology promising for broader applications.