Construction of PANI/Zn2In2S5 Heterojunction for Synergistically Enhanced Photocatalytic C-C Coupling of Methanol to Ethylene Glycol

The photocatalytic dehydrogenative coupling of methanol to produce the high-value-added chemical ethylene glycol (EG) has garnered widespread attention owing to its environmental benignity and mild reaction conditions. The ternary metal sulfide Zn2In2S5(ZIS), by virtue of its unique stoichiometric ratio, demonstrates a high intrinsic selectivity for the activation of the α-C-H bond in methanol. However, pristine ZIS faces the challenge of rapid recombination of photogenerated electron-hole pairs, which severely restricts its photocatalytic efficiency. In this study, the conductive polymer polyaniline (PANI) was successfully coupled with the ZIS photocatalyst via a simple one-step hydrothermal polymerization method to fabricate a series of PANI/ZIS nanocomposite photocatalysts. Systematic evaluation results indicate that the optimal catalyst, 7.5%-PANI/ZIS, exhibits exceptional catalytic performance under visible light, achieving an ethylene glycol generation rate as high as 4.87 mmol/g/h, representing a 6.76-fold enhancement over pristine ZIS (0.72 mmol/g/h). The significant performance enhancement is attributed to the synergistic effects of PANI and ZIS, which formed Type-II heterojunction effectively promotes the separation and transport of photogenerated charges and significantly reduces the charge transfer resistance. This research provides new insights into interfacial engineering based on conductive polymers and is of significant scientific importance for the high-value utilization of C1 small molecules.