2D/2D ZIF-L-Derived Zn<sup>δ+</sup> (0 ≤ δ ≤ 2) and N Codoped Carbon Skeleton@ZnIn<sub>2</sub>S<sub>4</sub> S-Scheme Heterojunction for Solar-Driven CO<sub>2</sub> Cycloaddition
Bin Jiang, Congcong Zhang, Na Yang, Qi Zhou, Longfei Zhang, Longfei Zhang, Jingshuai Li, Wei Yang, Xiaodong Yang, Luhong Zhang, Luhong Zhang
Abstract
Developing highly active photocatalysts that can directly utilize clean, cheap, and sustainable solar energy to achieve an efficient carbon dioxide (CO 2 ) cycloaddition reaction under mild reaction conditions (1 bar of CO 2 ) remains a great challenge. In this paper, 2D/2D ZnIn 2 S 4 /Zn-NC S-scheme heterojunction composites were constructed by the in situ growth of layered ZnIn 2 S 4 on the surface of two-dimensional (2D) ZIF-L-derived Zn δ+ (0 ≤ δ ≤ 2) and N codoped carbon skeletons (Zn-NC-T) via a low-temperature solvothermal method. The optimized ZnIn 2 S 4 /Zn-NC-T photocatalysts exhibited favorable photocatalytic CO 2 cycloaddition performance, and the yield of cyclic carbonate reached about 98.8% under 10 mmol epoxides reactant, 1 bar CO 2 pressure, and full-spectrum irradiation for 4 h. The favorable photocatalytic performance is attributed to the efficient photothermal conversion and effective separation of photogenerated carriers induced by the carbon matrix and heterojunctions, respectively. In addition, the stability of the heterojunction structure and activity were demonstrated through cyclic experiments. Furthermore, the possible mechanism of S-scheme heterojunction photocatalytic CO 2 cycloaddition is proposed through electron paramagnetic resonance (EPR) spectra, cyclic voltammetry (CV) experiments, and quenching experiments. The mechanism analysis proved that light irradiation is conducive to the transfer of photogenerated electrons from the conduction band of ZnIn 2 S 4 to epoxides, promoting the formation of ring-opening intermediates, and photogenerated holes may promote the coordination and polarization of adsorbed epoxides. This work not only prepared an S-scheme heterojunction catalyst with excellent photocatalytic CO 2 cycloaddition performance but also provided new insights for the rational design of heterojunction catalysts for photocatalytic CO 2 cycloaddition.