Greatly enhanced tribocatalytic degradation of organic pollutants by TiO2 nanoparticles through efficiently harvesting mechanical energy

Many piezoelectric nanomaterials have recently been revealed an attractive capability to degrade organic pollutants through utilizing mechanical energy via a tribocatalytic mechanism. Presently we have explored tribocatalytic degradation of organic pollutants for TiO2 nanoparticles. While degradation of organic dyes was observed for TiO2 nanoparticles under ordinary magnetic stirring, the degradation was greatly enhanced when the magnetic stirring was modified through using Teflon magnetic rotating disks, which are circular Teflon disks with a cross-shaped groove on one side and magnets mounted on the other side. With TiO2 nanoparticles under the modified magnetic stirring, as much as 99.7% of 40 mg/L Rhodamine B and 94.7% of 20 mg/L Methyl violet were degraded after 200 min, and 93.1% of 20 mg/L Methylene blue was degraded after 250 min, which are highly outstanding among catalytic dye degradations by metal oxide nanoparticles. Active radicals were detected through fluorescence spectroscopy and electron paramagnetic resonance spectroscopy for TiO2 nanoparticles under magnetic stirring, which supports a tribocatalytic mechanism for the dye degradations. These results suggest that tribocatalysis can be an appealing technology to utilize mechanical energy for environmental remediation, especially in areas of insufficient solar energy.