Bimetallic NiCu catalyst derived from spent MOF adsorbent for efficient photocatalytic CO2 reduction

The metal–organic frameworks (MOFs) rich in porous structures and their derivatives have been widely developed and applied to heavy metal adsorption. However, little attention has been paid to the subsequent treatment and reutilization of spent MOFs adsorbents. A potential feasible strategy is to develop MOFs-derived bimetallic catalysts for energy conversion. Herein, a bimetallic Ni-Cu2O-Cu/C nanocomposite (Ni-Cu/C) derived from spent Cu-based MOFs (CuBTC) adsorbents was fabricated and applied to improve the performance of photocatalytic CO2 reduction. The results demonstrate that Ni doping could improve the charge transfer dynamics. The synthesized Ni-Cu/C catalyst exhibits a high CO yield (12.45 μmol g−1 h−1) in the pure water system in the absence of other photosensitizers and sacrificial agents, which is 2.05 folds higher compared to Cu/C. The CO2 conversion selectivity of the synthesized Ni-Cu/C catalyst reaches up to 99.0%. The mechanism of photocatalytic CO2 reduction reaction was further investigated by in-situ experiments and density functional theory calculation. The in-situ FT-IR characterization show that photogenerated electrons could effectively adsorb CO2 to produce CO2− and optimize *CO immediate. This work not only emphasizes the unique design of bimetallic catalyst derived from spent MOFs adsorbent, but also contributes a feasible solution to its reutilization for enhanced CO2 conversion.