Plasmonic Cu-Assisted In₂O₃ Photothermal Catalysts for Directional Hydrogenation of CO₂ to Desired Methanol Product

Hydrogenation of CO2 to methanol (HCM) is a promising approach to convert CO2 greenhouse gas into high value-added chemicals. However, the high-temperature conditions required for CO2 activation are not beneficial to the HCM reaction due to its thermodynamically exothermic properties. In this case, photothermal technology is an attractive method to induce the HCM process under mild conditions, avoiding excessive heating energy input. In this study, a Cu nanoparticle (NP)-loaded In2O3 (Cu–In2O3) photothermal catalytic platform was designed via a simple coprecipitation method and further exploited for HCM implementation. Compared to conventional thermal-driven HCM, Cu NPs improve the methanol generation rate of Cu–In2O3 under photothermal reaction conditions, achieving an optimal methanol generation rate of 1260.0 μmol g–1 h–1. Cu NPs introduce the LSPR effect and more oxygen vacancies into Cu–In2O3, leading to a photothermal effect that promotes CO2 activation. Owing to the enhanced optical properties and high charge mobility, Cu NPs contribute to the photoexcited charge generation/separation in Cu–In2O3. Additionally, in situ DRIFT spectroscopy and DFT calculations demonstrate that the photothermal effect further improves the efficiency and selectivity of the HCM reaction over Cu–In2O3. This work confirms the great potential of Cu NPs in improving photothermal catalytic HCM efficiency on a metal oxide matrix. With sustainable solar energy assistance, the Cu–In2O3-based photothermal platform is expected to efficiently produce high value-added chemicals, such as methanol, from CO2 greenhouse gas under mild conditions.