Engineering NH2-MIL-125(Ti)@ZnIn2S4 S-scheme heterostructure for boosting CO2 photoreduction

Metal-organic framework (MOF) based heterojunctions offer a promising strategy for CO 2 photoreduction, contributing to carbon neutrality and environmental remediation. However, the precise design and control of these heterostructures remain critical challenges. Herein, we report the precise construction of a heterostructure by integrating 2D ZnIn 2 S 4 nanosheets with NH 2 -MIL-125(Ti) for efficient CO 2 photoreduction in a sacrificial agent-free environment. A comprehensive investigation demonstrates robust interfacial interactions and work function differences between NH 2 -MIL-125(Ti) and ZnIn 2 S 4 , facilitating the formation of an interfacial electric field and enabling the construction of an S-scheme heterojunction. The directional migration of photogenerated charge carriers effectively suppresses their recombination, retaining the strong oxidative and reductive potential of the heterostructure components. In-situ infrared spectroscopy provides concrete evidence that the S-scheme heterojunction significantly enhances the formation of key intermediates, which are crucial for CO generation. The optimized NMT-5@ZIS achieves a CO yield of 17.30 umol g -1 h −1 without sacrificial agents, representing 8.6 and 6.6-fold improvements over pristine NH 2 -MIL-125(Ti) and ZnIn 2 S 4 , respectively. This work bestows an innovative insight into the construction of MOF-based S-scheme heterojunctions, opening new avenues for practical applications in energy storage and photocatalysis.