Hexagonal In2O3 short nanorods rich in O vacancy-defects toward promoting highly efficient photothermal CO2 reduction into C2H5OH

Abstract

Harnessing solar energy to catalytically reduce CO₂ into chemical fuels represents a promising solution to simultaneously address the energy crisis and global warming. However, the efficient and selective synthesis of high value-added products under relatively mild conditions remains a challenge. Herein, a catalyst composed of hexagonal In₂O₃ (abbrev. as h-In₂O₃) short nanorods with a high specific surface area was synthesized via a straightforward solvothermal method. Compared to commercial cubic In₂O₃ (abbrev. as com-In₂O₃), the h-In₂O₃ short nanorods exhibited high yield in the photothermal reduction of CO₂ to CO, CH₄, CH₃OH, and C₂H₅OH, using water vapor as the reducing agent. With oxygen vacancies being introduced into h-In₂O₃ through H₂ treatment, C₂H₅OH yield rate represents a remarkable 5.89 times and 13.22 times higher than h-In₂O₃ and com-In₂O₃, respectively. The product selectivity of C₂H₅OH for V_O-In₂O₃ reached an impressive 47.07%, far surpassing 11.37% for com-In₂O₃ and 12.84% for h-In₂O₃. Electrochemical measurement and in situ DRIFTS spectra indicate that the introduction of O vacancies could contribute to the reduced recombination of photogenerated carriers and the enhanced dissociation of H₂O, which may be beneficial to the improvement of C₂H₅OH yield and selectivity.