Co-ZIF-derived dual Co and Co3S4 nanoparticles encapsulated in N-doped carbon matrix for efficient photocatalytic CO2 reduction

In this study, a novel N-doped carbon-coated dual Co and Co3S4 nanoparticles composite (Co-Co3S4@NC) has been developed by pyrolysis of an ideal flower-like Co-ZIF precursor followed via subsequent hydrothermal sulfidation. Under visible-light irradiation, the Co-Co3S4@NC exhibits outstanding performances for CO2 reduction with H2O vapor into CO (23.14 μmol g−1 h−1) and CH4 (0.62 μmol g−1 h−1) in a continuous flow system, significantly outperforming the single Co@NC photocatalyst. The experimental results demonstrate that the energy band structure in Co-Co3S4@NC can provide a more favorable reduction potential for the effective reduction of CO2. Moreover, the presence of Co3S4 is beneficial for the rapid separation and transfer of charges, thereby enhancing the utilization of photogenerated charge carriers. Thanks to its unique composition, Co-Co3S4@NC possesses abundant active sites for chemisorption and activation of CO2, which facilitates CO2 photoreduction. The reaction mechanism is revealed in detail by analyzing the key intermediate species obtained through in situ DRIFTS. The current work offers a facile route for the construction of MOF-derived composites for promising photocatalytic reactions.