Unveiling the role of N species in Co/NC catalysts for photothermal CO2 hydrogenation

Abstract

Generally, researchers focus on the regulation of metal sites rather than surrounding nonmetals in photothermal CO₂ hydrogenation reaction. Herein, concerning the role of non-metallic N species, a series of Co/NC-T catalysts have been fabricated via high-temperature pyrolysis of Zeolitic Imidazolate Frameworks-67. The CO₂ conversion rate shows a consistent tendency with the ratio of graphitized-N species while the product selectivity is closely related to the coordination state of Co-N_x species. Co/NC-800 catalyst achieves high CO₂ conversion rate of 758 mmol g_cat^-1 h^-1 with CH₄ selectivity of 99.6 %. After adding extra graphitized-N species, the CO₂ conversion rate could further enhance to 80.2 % for N-Co/NC-2. The role of N species in photothermal CO₂ hydrogenation reaction has been investigated in details, providing new insights for the design of metal organic frameworks derived metal/N-doped carbon catalysts.