Boosting tribo-catalytic degradation of organic pollutants by BaTiO3 nanoparticles through metallic coatings

Recently, tribo-catalysis has emerged as an appealing technology to harvest mechanical energy for environmental remediation. While most investigations have focused on catalyst optimization to enhance tribo-catalytic degradation, here we studied the effects of some metal disks placed on beaker bottoms (named coatings) on the tribo-catalytic degradation by BaTiO3 (BTO) nanoparticles under magnetic stirring. For 20 mg/L Rhodamine B (RhB) solution, Cr, Cu, and Ti coatings improved the kinetic constants of BTO nanoparticles by 3.1, 3.4, 5.2 folds, respectively. Ti coating was further found to result in 99 % degradation in just 3 h for 50 mg/L RhB solution, and elevate the kinetic constants by 19.1 and 16.6 folds for 20 mg/L methyl orange (MO) and 20 mg/L methylene blue (MB) solutions, respectively. EPR, FL and UV–vis spectroscopy verified that modifying vessel bottom with Ti coating enabled BTO nanoparticles to generate more active species. First-principles calculations of the work functions of Cr, Cu, and Ti surfaces, and the energy-band structure of BTO revealed a decreased electron-hole recombination rate due to the transfer of excited electrons to metallic coatings. These results suggest that modifying vessel bottoms with suitable metallic coatings is a simple, eco-friendly and efficient strategy to boost tribo-catalysis for environmental remediation.