Optimizing Materials\nto Boost the Valorization of\nCO<sub>2</sub>: Tuning Cobalt–Cobalt Interactions on In<sub>2</sub>O<sub>3</sub>‑Based Photothermal Catalysts

The valorization of CO<sub>2</sub> is an important challenge\nwithin\nthe current panorama, since this molecule is probably the main contributor\nto climate change. In this study, the synthesis of materials based\non a nanostructured batonnet-type indium oxide is carried out. In\nthem, different amounts of Co are introduced, varying between 2 and\n8% mol. It is verified that the most active sample in the transformation\nof carbon dioxide to carbon monoxide contains 6 mol %. of Co. This\nsample’s activity under dual excitation exceeds the thermal\ncounterpart by more than 30%. After carrying out a complete physical\nand chemical characterization with the help of X-ray absorption spectroscopy\nand other techniques, it is shown that catalysts with amounts of cobalt\nequal to or below 4 mol % contain isolated single-atom species, while\nthose with higher amounts of metal display a Co–Co interaction\nwhich triggers the evolution of the samples under reaction conditions.\nThe optimum control of this Co–Co interaction and the nature\nof the final cobalt-containing species determine dual photothermal\ncatalytic properties. This work establishes a structure–activity\nrelationship to interpret the catalytic behavior of highly dispersed\nsubnanometric cobalt species, and thus an avenue to optimize the photothermal\nvalorization of carbon dioxide.