Ti-MOF-derived Ti3+-TiOx/CdIn2S4 heterojunction with a hollow structure for enhanced photocatalytic activity under visible light

The removal of refractory organic contaminants in the environment is vital, but developing highly active catalysts with a simple synthesis process remains a challenge. Herein, NH2-MIL-125(Ti) (Ti-MOF) as a template, Ti3+TiOx clusters of different quantities were embedded in the CdIn2S4 nanosheets to construct Ti3+-TiOx/CdIn2S4 (TiCIS) heterojunction by an in-situ self-assembly strategy, which had a hollow structure, strong visible light absorption, high separation rate of carriers, and more active sites. During the degradation experiment of Rhodamine B (RhB), TiCIS25 exhibited the best photocatalytic performance, and 98.0% of RhB was degraded within 60 min of visible irradiation. The intermediates in the RhB degradation and their ecotoxicity were analyzed, which revealed that RhB degradation was a detoxification process. The radical trapping experiments and electron spin resonance (ESR) tests indicated that e-, 1O2, and & sdot;O2- are the main active species for RhB degradation. Moreover, a possible photocatalytic mechanism was proposed based on electrochemical tests. The photodegradation performance of the as-prepared TiCIS catalyst under different reaction parameters (authentic water matrices, initial pH, coexisting anions, organic matter concentration, actual sunlight, reaction temperature, and multiple pollutants) and circulating experiments, as well as the photo-reduction process CO2, reflected that TiCIS25 possessed excellent practicability, cyclic stability, and universal applicability. Above all, TiCIS25 exhibited great potential in photocatalytic processes, and the work provided a feasible strategy for designing high-performance photocatalysts.