Coupling MOF-derived titanium oxide with CdIn2S4 formed 2D/3D core–shell heterojunctions with enhanced photocatalytic performance

Two-dimensional (2D) disk-like shape titanium oxide with controllable phase was prepared using NH2-MIL-125(Ti) as template by pyrolysis at different atmospheres process to acquire TiO2 (3.09 eV, air) and A/R-TiO2 (2.81 eV, N2). Subsequently, 2D/3D core–shell heterostructures (CdIn2S4@TiO2 and CdIn2S4@A/R-TiO2) were built by in-situ self-assembly tactics. Characterization displayed that the 3D CdIn2S4 shell with diameter 5.5 μm was uniformly wrapped on the surface of 2D A/R-TiO2 and TiO2 core with 3 μm. Compared with CdIn2S4@TiO2 (74.27 m2/g), the CdIn2S4@A/R-TiO2 possessed higher BET surface area (106.54 m2/g), providing larger contact areas and exposed more active sites. And CdIn2S4@A/R-TiO2-1.2 showed the best photocatalytic degradation and hydrogen production, which was much higher than that of CdIn2S4@TiO2-0.8. The mechanism of the proposed photocatalysis is further discussed: the CdIn2S4@TiO2 followed the Z-scheme mechanism while the Ti3+ and Ti4+ redox sites generated in A/R-TiO2 could be mutually transformed in situ and CdIn2S4@A/R-TiO2-1.2 followed the Ⅱ-scheme mechanism.