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

MXene Schottky Functionalized Z‑scheme Ternary Heterostructure for Enhanced Photocatalytic H₂O₂ Production and H₂ Evolution

The design and development of a multiheterostructure interface signifies a promising route to overcome the drawbacks of single-component and traditional heterostructured photocatalysts. Herein, a one-dimensional (1D)/two-dimensional (2D)/2D heterostructure, α-MnO2@B/O-g-C3N4/d-Ti3C2, is constructed by a facile two-step synthesis method to ensure charge separation and is utilized for photocatalytic H2O2 production and H2 evolution. The formation of the individual materials and nanohybrids as well as the 1D/2D/2D interfacial interaction is ascertained by X-ray diffraction, Raman, and electron microscopy studies, respectively. 5-MX/MBOCN shows optimum photocatalytic H2O2 production (2846.4 μmol h–1 g–1) with 10% ethanol and H2 evolution (897.2 μmol h–1), which is, respectively, 2.5 and 1.6 times higher than that of the binary MBOCN counterpart. The greater cathodic current density from linear sweep voltammetry, hindered charge recombination from electrochemical impedance spectroscopy and photoluminescence measurement, and better photodurability all systematically demonstrated the improved photocatalytic performance. The mechanistic investigation shows that in the ternary hybrid, electrons flow from MnO2 to boron-doped g-C3N4 through a Z-scheme charge dynamics and then electrons flow to the d-MXene surface, which acts as a cocatalyst. The charge transfer dynamics is corroborated by time-resolved photoluminescence, cyclic voltametric analysis, trapping experiment, and ESR analysis. This work instigates the design and development of a high-efficiency cocatalyst-integrated Z-scheme photocatalyst with strong interfacial interaction and high redox ability for solar to chemical energy conversion