Wurtzite/Kesterite Cu2ZnSnS4 S-Scheme Heterophase Junction: A Robust Catalyst for Photothermal-Assisted Photocatalytic CO2 Reduction and Environmental Remediation

Heterophase junction engineering offers a revolutionary strategy for constructing polymorph photocatalysts with nearly perfect interfacial matching, thereby significantly optimizing charge dynamics. Nevertheless, existing heterophase junction systems still struggle to achieve both directional charge separation and efficient utilization of the full solar spectrum. In this study, a wurtzite-phase Cu2ZnSnS4 (W-CZTS)/kesterite-phase Cu2ZnSnS4 (K-CZTS) S-scheme heterophase junction was successfully constructed through the precise regulation of the spatial assembly between W-CZTS nanoparticles and K-CZTS nanosheets. This strategic structural design achieved three key breakthroughs: (i) the formation of atomically intimate interfaces with strong built-in electric fields, (ii) the integration of superior photothermal conversion capability, and (iii) directional charge separation while preserving optimal redox potentials. The developed heterophase junction catalyst demonstrated outstanding photothermal-assisted photocatalytic performance: under UV–vis–IR illumination, the average CO yield reached 68.4 μmol g–1 h–1, which represented a 9.6-fold enhancement compared to that without IR irradiation, and 76-fold and 114-fold higher than the performance of pristine K-CZTS and W-CZTS, respectively, under UV–vis irradiation. Furthermore, the catalyst demonstrated near-complete removal efficiency for both Cr(VI) reduction and Congo red degradation. This study establishes a paradigm for the development of high-performance heterophase junction photocatalysts and provides crucial insights for advancing solar-driven environmental remediation and fuel production.