Synergy of surface oxygen vacancies and built-in electric field in 0D/2D CeO2/SnSe2 S-scheme heterojunctions for enhanced photocatalytic malachite green degradation

Abstract Industrial effluents exacerbate aqueous contamination, necessitating the urgent remediation of toxic dyes such as Malachite Green (MG). In this study, a 0D/2D S-scheme heterojunction was constructed by anchoring CeO 2 nanocubes onto SnSe 2 hexagonal nanosheets via a precisely controlled two-step hydrothermal strategy. In-situ electron paramagnetic resonance (EPR) analysis corroborates that illumination triggers the proliferation of surface oxygen vacancies. These photo-induced oxygen vacancies (Ov) empower the CeO 2 /SnSe 2 heterostructure to sustain exceptional catalytic activity over five consecutive cycles. Moreover, the optimized 0.2 g CeO 2 /SnSe 2 composite exhibits a remarkable degradation efficiency of over 98% for MG within 30 minutes. Such performance enhancement is attributed by the synergy between the 0D/2D dimensional matching and a potent internal electric field (IEF), which triggers an S-scheme charge transfer mechanism to preserve high redox potential while accelerating carrier separation. This work provides a sophisticated blueprint for designing dimension-matched S-scheme heterojunctions for high-performance environmental remediation.