Co-ZIF-derived dual Co and Co 3 S 4 nanoparticles encapsulated in N-doped carbon matrix for efficient photocatalytic CO 2 reduction

In this study, a novel N -doped carbon -coated dual Co and Co 3 S 4 nanoparticles composite (Co-Co 3 S 4 @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-Co 3 S 4 @NC exhibits outstanding performances for CO 2 reduction with H 2 O vapor into CO (23.14 mu mol g - 1 h -1 ) and CH 4 (0.62 mu mol 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-Co 3 S 4 @NC can provide a more favorable reduction potential for the effective reduction of CO 2 . Moreover, the presence of Co 3 S 4 is beneficial for the rapid separation and transfer of charges, thereby enhancing the utilization of photogenerated charge carriers. Thanks to its unique composition, CoCo 3 S 4 @NC possesses abundant active sites for chemisorption and activation of CO 2 , which facilitates CO 2 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.