MOFs-derived Cu3P@CoP p-n heterojunction for enhanced photocatalytic hydrogen evolution

Abstract

In this study, we developed a novel in situ growth scheme to construct the Cu-MOFs@ZIF-9(Co) core-shell precursor material. The Cu-MOFs@ZIF-9(Co) core-shell precursor was treated by low-temperature phosphorization to obtain a Cu3P@CoP composite catalyst with a self-supporting structure. Cu3P@CoP composite catalyst not only had a hierarchical structure, but also built a p-n heterojunction at the interface. The unique structure and composition of Cu3P@CoP could promote charge migration and provide large surface area and rich active sites to drive water photolysis. In addition, by controlling the degree of phosphation of Cu-MOFs@ZIF-9(Co) material and adjusting the ratio of Cu and Co, it was found that the maximum hydrogen-producing activity of the composite photocatalyst reached 469.95 μmol (9399 μmol h−1 g−1), and it had a very excellent cycle stability. The results of photoelectrochemical and fluorescence tests showed that the proper conduction and valence band positions of Cu3P and CoP formed a more effective path way for the thermodynamic charge transfer. The construction of p-n type heterojunction provided a fast electron transfer channel in the Cu-P@Co-P interface. The formed special structrue and the existence of the bult-in electric filed in the p-n heterojunction made the photogenerated carriers in the composite have more effective separation and lower recombination rate, which significantly enhanced H2 production activity. At the same time, our work will provide a new strategy for the rational design of efficient catalysts of MOFs derivatives and a new direction for the design of transition metal phosphide photocatalysts.