Tunable C2 Products via Photothermal Steam Reforming of CO2 over Surface-Modulated Mesoporous Cobalt Oxides

The conversion of CO2 to high-value products by renewable energy is a promising approach for realizing carbon neutralization, but the selectivity and efficiency of C2+ products are not satisfying. Herein, we report the controllable preparation of highly ordered mesoporous cobalt oxides with modulated surface states to achieve efficient photothermal water-steam reforming of CO2 to C2 products with high activity and tunable selectivity. Pristine mesoporous Co3O4 exhibited an acetic acid selectivity of 96% with a yield rate of 73.44 μmol g–1 h–1. By rationally modifying mesoporous Co3O4 surface states, mesoporous Co3O4@CoO delivered a radically altered ∼100% ethanol selectivity with a yield rate of 14.85 μmol g–1 h–1. Comprehensive experiments revealed that the pH value could strongly influence the selectivity of C2 products over mesoporous cobalt oxides. Density functional theory verified that reduced surface states and rich oxygen vacancies on surface-modified mesoporous cobalt oxides could facilitate further variation of C2 products from acetic acid to ethanol.