Piezo-photocatalytic degradation and mechanism of rhodamine B by flexible MoSe2/PVDF composite foam

Photocatalysis is based on ultraviolet light, while piezoelectric catalysis is powered by mechanical energy and piezoelectric effect. Both types of catalysis have been employed in degradation of pollutants and wastewater treatment. In this work, molybdenum diselenide (MoSe2) was mixed with polyvinylidene difluoride (PVDF) to produce a MoSe2/PVDF composite foam with flexible porous structure. The composite foam exhibited excellent light absorption and effective Rhodamine B (RhB) removal. MoSe2 could enhance the piezoelectric catalytic performance of PVDF by promoting the formation of β-phase. In addition, this composite foam piezo-photocatalytically removed more than 99.1 % of RhB within 60 min under light irradiation and stirring. In electron spin resonance (ESR) and capture active species experiments, it was found that •OH, •O2− and h+ contribute to the removal of RhB. The Fukui function based on Density Functional Theory (DFT) and mass spectrometry were used to identify the degradation pathway of RhB. The evaluation results of toxicity evaluation software (T.E.S.T.) to degradation intermediates of RhB showed that the overall toxicity gradually decreased in degradation process. Due to the existence of MoSe2, the composite represented an outstanding evaporation rate (2.23 kg m−2 h−1) under one solar irradiation. Furthermore, MoSe2/PVDF also exhibited remarkable antibacterial properties, which is favorable to its practical application. This work presents a novel high-performance piezo-photocatalysis material, which proposes innovative environmental governance strategies for obtaining clean water through multi-component synergism.