Core–Shell MIL-125(Ti)@In<sub>2</sub>S<sub>3</sub> S-Scheme Heterojunction for Boosting CO<sub>2</sub> Photoreduction
Mazhar Khan, Zeeshan Akmal, Muhammad Tayyab, Seemal Mansoor, Dongni Liu, Junwen Ding, Ziwei Ye, Jinlong Zhang, Shiqun Wu, Lingzhi Wang
Abstract
Heterojunctions based on metal–organic framework (MOF) materials have emerged as promising systems for CO 2 photoreduction under sacrificial agent-free conditions. However, the rational design and precise construction of these heterostructures remain significant challenges. In this study, we report the development of a core–shell heterojunction via the in situ growth of In 2 S 3 nanosheets on MIL-125(Ti) for efficient CO 2 photoreduction. Comprehensive characterization elucidates strong interfacial interactions and substantial work function mismatches between MIL-125(Ti) and In 2 S 3, which drive the formation of a robust interfacial electric field (IEF) and facilitate the establishment of an S-scheme heterojunction. The S-scheme heterojunction retains the strong oxidative and reductive potentials of its components, promoting efficient charge separation and transfer. In situ infrared spectroscopy provides evidence that the formation of the S-scheme heterojunction significantly enhances the production of critical intermediates essential for the CO 2 reduction process. Moreover, density functional theory calculations reveal that the heterojunction construction significantly facilitates CO 2 activation and lowers the energy barrier. The optimized MT-2@IS achieves an exceptional CH 4 production rate of 27.65 μmol g –1 h –1 without the use of photosensitizers or sacrificial agents, representing 27-fold and 8.9-fold improvements compared to pristine MIL-125(Ti) and In 2 S 3 . This work provides valuable insights into the design of MOF-based heterojunctions and establishes a robust framework for advancing CO 2 photoreduction technologies.