Black phosphorus-based semiconductor multi-heterojunction TiO2-BiVO4-BP/RP film with an in situ junction and Z-scheme system for enhanced photoelectrocatalytic activity

A new method combined ball-milling with hydro-thermal was reported to fabricate black/red phosphorus (BP/RP) in situ junction, which was further utilized to prepare a novel multi-heterojunction TiO2-BiVO4-BP/RP film. The composite film was well characterized, which proved that multi-heterojunction had been formed, and faceto-face contacted Z-type channel between BiVO4 and BP played a key role in promoting the electrons transfer with a carrier density of 18.97 x 10(22) cm(-1). The TiO2-BiVO4-BP/RP film exhibited a significant enhancement in photoelectrocatalytic (PEC) activity towards degrading fluxapyroxad (FLX), an emerging fluorinated fungicide. The degradation rate achieved 96.5% in 120 min of simulated solar irradiation with an external voltage of 1 V, and notably, the defluorination rate reached 45.41%. The mechanisms and degradation pathways were further discussed, indicating TiO2-BiVO4-BP/RP film possessed a strong redox capacity and a direct hole oxidation process owing to the synergism of the multi-heterojunctions, and the increase in radical amount and apparent quantum yield (21.3%) according to ESR analysis and reaction kinetics. Furthermore, TiO2-BiVO4-BP/RP film showed an excellent PEC performance in comparison with TiO2-BiVO4-phosphonene due to the BP/RP in situ junction. The catalyst also showed excellent stability and recyclability, the degradation rate of FLX can still reach 90% after 10 runs of PEC experiment without any further treatment. Thus, the current study provided a novel way for design and fabrication of BP-based catalysts in removal of fluorinated organic pollutants in wastewater.

Automated summary

A novel method combining ball-milling with hydro-thermal was reported for fabricating a TiO2-BiVO4-BP/RP film, which exhibited enhanced photoelectrocatalytic activity towards degrading a fluorinated fungicide. The face-to-face contact between BiVO4 and BP, as well as the synergistic effects of the multi-heterojunctions, played key roles in promoting electron transfer and enhancing radical generation. The BP/RP in situ junction contributed to the superior performance of the catalyst in comparison with other phosphonene-based catalysts, leading to excellent stability and recyclability in the removal of fluorinated organic pollutants in wastewater.