Non-piezoelectric SiO₂ amorphous nanomaterials for highly tribocatalytic water purification

Being widely available in the earth's rock layers, SiO₂ is among the earth's most thoroughly distributed natural mineral resources. Here, non-piezoelectric amorphous SiO₂ mineral nanoparticles have been experimentally designed for efficient tribocatalytic dye degradation under mechanical friction provided by 400-1200 rpm low-velocity stirring. The friction between the catalyst surface and the stirring rod leads to the generation of positive and negative charges, which react with hydroxide and oxygen, respectively, in the dye solution to produce some active substances, resulting in tribocatalytic organic dye degradation. After being mechanically stirred at 1000 rpm for 6 h using amorphous SiO₂ mineral nanoparticle catalysts, ∼95.2% of Rhodamine B dye can be obviously degraded. Radical trapping experiments show that ˙OH and ˙O₂^- are the main active substances. Furthermore, increasing the contact area or the friction contact interface's roughness is helpful for enhancing the tribocatalytic performance. After 3 recycling cycles, the SiO₂ nanoparticles can still degrade ∼89.2% of RhB dye. These low-cost SiO₂ mineral nanoparticles, with the advantage of being widely distributed, have the potential to harvest common environmental mechanical friction energy for the purpose of organic pollutant degradation.