ZrN@g-C3N4 Heterojunction Mimicking Thylakoid to Enhance Photoelectrochemical Reduction of Carbon Dioxide to C2 Chemicals

Abstract

The photoelectrochemical (PEC) reduction of carbon dioxide to value-added chemicals presents a promising strategy for mitigating the energy crisis and environmental issues. Herein, we report a facile approach for constructing an inorganic/organic semiconductor heterojunction between g-C3N4 and ZrN, which is endowed with intrinsically stable radical species. The ZrN@Nv-CN-x electrodes demonstrated high activity in PEC CO2 reduction in light of good CO2 adsorption, narrowed band gap, efficient charge separation, and stable N-heterocyclic radicals verified by EPR experiments. The C2+ selectivity of the optimal catalyst ZrN@Nv-CN-2 rose to 84.31%. The ZrN@Nv-CN-2|SCE|BiVO4 cell efficiently generates organic chemicals at a rate of 30.86 μmol L–1 h–1 cm–2, exhibiting an evidently synergetic effect between photocatalysis and electrocatalysis. Furthermore, a plausible mechanism was suggested according to the active species (*═C═O, *CHO, *COO–, and *COCHO) presented in in situ FTIR spectra and was verified by DFT calculations. This simple strategy might provide a perspective for the development of robust catalysts for C2+ products.