In-situ growth of MOF nanosheets with controllable thickness on copper foam for photoelectrocatalytic CO2 reduction

CuBDC (BDC = 1, 4-benzenedicarboxylate) nanosheets, growing on copper foam (CF) in situ, were synthesized by solvothermal method for photoelectrocatalytic CO2 reduction. Importantly, the thicknesses of nanosheets could be well-regulated by controlling the volume ratio of a mixed solvent [N, N-dimethylformamide (DMF), absolute ethanol (EtOH), and deionized water (H2O)]. In the mixed solvent, DMF and EtOH acted as common solvents, and nanosheets grew perpendicular with the substrate. Intriguingly, H2O was introduced to the Cu sites of CuBDC in the coordination process. Nanosheets began to become thick because of the strong attraction of hydrogen bonds of water molecules. Using CuBDC/CF material as photocathode, the photoelectrocatalytic performance of CO2 reduction was evaluated. It has been demonstrated that CuBDC/CF prepared by using the mixed solvent (VDMF:VEtOH:\({\text{V}}_{\text{H}_2{\text{O}}}\) = 16:1:1) exhibited high catalytic activity for CO2 reduction under photoelectrocatalytic conditions. Owing to proper thickness, it can achieve good CO2 adsorption and effective electron transfer. Faradaic efficiency of total products of C1 chemicals such as CO, CH4 reached 13%.