Challenges and perspectives of tribocatalysis in the treatment for dye wastewater

Recently, there appears an emerging tribocatalysis technology which works well under water flow disturbance without any photo-energy or additional electric-energy. At present, investigations about tribocatalysis have focused on catalytic mechanism, resulting in a lack of researches on the types, structure and catalytic performance of tribocatalyst, so it is necessary to analyze systematically tribocatalysis and give some valuable insights in application of dye wastewater. In this review, the types and structures of friction catalysts were both classified and discussed. Meanwhile, factors influencing tribocatalytic degradation and mechanism were also analyzed detailedly. Factors affecting tribocatalytic efficiency can be divided into internal and external two aspects. The internal factor mainly refers to electronic structure of catalysts and the external aspect involves in the hydraulic conditions of tribocatalytic reactions. The essence of tribocatalsis is the transfer of charges or electrons, so it is important to clarify the generation and transfer pathway of charges or electrons in tribocatalytic reaction. Some researches regard as electron transfer should be responsible for tribocatalytic mechanism, and the other think that the transition of electron coming from conductive band of catalyst should be in charge of tribocatalytic mechanism. In fact, the tribocatalytic mechanism strongly depends on catalyst's electronic structure and bandgap width, which was analyzed wholly in this review. This work aims to provoke a meaningful discussion and provide some valuable insights and prospects for tribocatalysis in dye wastewater treatment.