Tribo-catalytic degradation of organic pollutants through bismuth oxyiodate triboelectrically harvesting mechanical energy

As an old physical concept, triboelectrification is a common phenomenon in different mechanical movements and always plays a negative effect on our daily life. Collection of triboelectricity from ambient mechanical energy recently has been realized via a triboelectric nanogenerator (TENG). Herein, we successfully used the triboelectricity from the magnetic stirring induced friction to catalytic degradation of organic dyes, therefore realizing the conversion of mechanical energy to electric energy and finally to chemical energy. The tribo-catalyst of BiOIO3 exhibited an efficient catalytic activity where the dye degradation reached >90% after 6 h magnetic stirring, and meanwhile showed a superior durability. The charge exchange during the friction between catalyst and magnetic bar or beaker and the subsequent reaction of charges with aqueous solution to produce reactive oxygen species are considered to be responsible for the tribo-catalysis. However, due to the positive edge potential of conduction band (CB) of BiOIO3, superoxide radicals cannot be generated by the reduction of dissolved oxygen with the electrons on CB. As a result, the holes on valence band (VB) and the hydroxyl radicals are mainly active species for dye degradation. This finding well demonstrates that catalysis reactions can be initiated by triboelectric charges on catalyst during harvesting small ambient mechanical energy.