Modulating CoFeO X Nanosheets Towards Enhanced CO 2 Photoreduction to Syngas: Effect of Calcination Temperature and Mixed-Valence Multi-Metals.

CoFeO X nanosheets were synthesized by a facile coprecipitation and calcination method. The effect of calcination temperature on the crystal texture, morphology and surface areas of CoFeO X were fully explored. CoFeO X sample calcined at 600 °C (CoFeO X -600) showed superior catalytic performance for the reduction of CO 2 under visible light. Compared with the pure Ru(bpy) 3 2+ -sensitized CO 2 reduction system, the CoFeO X -added system achieved 19-fold enhancement of CO production (45.7 μmol/h). The mixed valence state and nanosheet-like structure of CoFeO X cocatalyst support its ultra-high charge transfer and abundant CO 2 active adsorption sites exposure, which promote the separation of photogenerated charges, and thus improve the photocatalytic CO 2 reduction activity. Carbon source of CO from CO 2 was verified by 13 CO 2 isotopic labelling experiment. Repeated activity experiments confirmed the good stability of CoFeO X in the CO 2 photoreduction system. This work would provide prospective insights into developing novel cost-effective, efficient, and durable non-precious metal cocatalysts to improve the efficiency of photocatalytic reduction of CO 2 .