Regulating nitrogen activation and proton supply to boost photocatalytic nitrogen fixation via Co-ZnO/ MIL-125(SH)2 S-scheme heterojunction

More efficient N 2 activation and carrier dynamics are needed for effective solar-driven ammonia synthesis. Herein, a heterojunction photocatalyst (Co-ZnO/MIL-125(SH) 2 ) was constructed by using MIL-125(Ti) with sulfhydryl functionalization and Co-doped ZnO for photocatalytic nitrogen fixation. A series of characterization reveal that the formation of S-scheme charge transfer greatly enhances interfacial charge separation for more available carriers. The presence of Ti 3 + sites in MIL-125(SH) 2 also facilitates the adsorption and activation of N 2 , effectively leveraging the photogenerated electrons for N 2 conversion. Moreover, the introduction of Co-ZnO increases the hydrophilicity of the catalytic surface. This allows more water molecules to be oxidized by photogenerated holes to release H + for the N 2 hydrogeneration process. As a result, a high photocatalytic ammonia production rate of 50.8 μmol•g −1 •h −1 is achieved under visible light irradiation. This study presents an insight into engineering S-scheme heterojunction composite by coupling molecular coordinate activation and improved protons supply for efficient photocatalytic nitrogen fixation.