Interfacial Solid-State Mediator-Based Z-Scheme Heterojunction TiO2@Ti3C2/MgIn2S4 Microflower for Efficient Photocatalytic Pharmaceutical Micropollutant Degradation and Hydrogen Generation: Stability, Kinetics, and Mechanistic Insights

Interface engineering is a vital concern to achieve high efficiency in heterojunction photocatalysts. The judicious design of efficient interfacial electron mediators to accelerate the charge transfer efficiency in Z-scheme heterojunctions with interfacial contact for enhancing the performance of photocatalysts is essential and has been considered an immense challenge. Inspired by nature, multivariate all-solid-state Z-scheme TiO2@Ti3C2/MIS heterojunction composites were fabricated via a simple two-step oxidation strategy for highly promoted multiple photocatalytic applications. The morphological analysis of TiO2@Ti3C2/MIS composites demonstrated that MgIn2S4 (MIS) microflowers were accumulated on the surface of Ti3C2@TiO2 nanosheets, providing dense active sites to the MIS microflowers for efficient photocatalytic applications. The HRTEM and XPS characterization distinctly clarified the close interfacial interaction between MIS with Ti3C2 and TiO2. The optimized TiO2@Ti3C2/MIS-15 photocatalysts exhibited the highest photocatalytic ciprofloxacin degradation (92%) and hydrogen evolution (520.3 μmol h–1) as compared to those of their pristine counterparts. From the mechanistic insights, the charge migration pathway was observed between MIS and TiO2, where Ti3C2 nanosheets served as an electron bridge in constructing the Z-scheme and thus extended the lifetime of the charge carriers photoinduced by MIS and TiO2. The significant participation of •O2– and •OH radicals during photocatalytic CIP degradation was verified by active species trapping experiments, EPR, and liquid chromatography–mass spectrometry (LC-MS) analysis. The current study provides a strategy to design mediator-based Z-scheme heterojunction interfaces for improving the catalytic activity of MXene-derived photocatalysts.