Superior Fenton-like and photo-Fenton-like activity of MoS2@TiO2/N-doped carbon nanofibers with phase-regulated and vertically grown MoS2 nanosheets

Molybdenum disulfide (MoS2) nanosheets were recently found to have great potential in heterogeneous Fenton-like reactions, but the synergistic effects of its phase and vertical structure on activating hydrogen peroxide (H2O2) remain ambiguous. Herein, a series of 1 T/2H MoS2@TiO2/NCNFs were constructed by vertically growing trigonal phase (1 T)/hexagonal phase (2H) MoS2 on self-supported titanium dioxide/nitrogen-doped carbon nanofibers (TiO2/NCNFs) for Fenton-like and photo-Fenton-like degradation of tetracycline (TC). It was found that metallic 1 T phase MoS2 favors the dark-Fenton-like reaction, but proper biphase 1 T/2H MoS2 benefit the photo-Fenton-like reaction. This depends on the high electron transport rate of 1 T MoS2 and the photocatalytic effect of 2H MoS2. Significantly, the vertical structure MoS2 nanosheets were much more effective in promoting H2O2 activation than phase regulation. In dark, the reaction rate constant for the optimized vertical 1 T/2H MoS2@TiO2/NCNFs was 0.0246 min−1, which was 16.4 times that for stacked MoS2 (0.0015 min−1). Quenching experiments indicated that •O2–, •OH and h+ were all involved in the photo-Fenton-like reaction, whereas •OH predominated the dark-Fenton-like reaction. The probable TC degradation pathways were investigated and proposed. Besides, the optimized 1 T/2H MoS2@TiO2/NCNFs demonstrated excellent stability, recyclability and adaptability. This work is instructive for designing highly efficient MoS2-based Fenton-like or photo-Fenton-like catalysts.