Tribocatalytic Degradation of Organic Pollutants Using Fe2O3 Nanoparticles

Tribocatalysts possessing advantages of high performance, eco-friendliness, and low cost also without causing secondary pollution are ideally and highly desirable for practical applications but remain challenging. Here, we demonstrate that eco-friendly and low-cost Fe2O3 nanoparticles exhibit superior tribocatalytic performance through harvesting low-frequency mechanical energy. Rhodamine B (RhB) is completely degraded by Fe2O3 nanoparticles within 15 h under low-frequency magnetic stirring, and the catalytic efficiencies are always maintained above 96% during five consecutive cycles. Systematical experimental explorations indicate that the tribocatalytic performance of Fe2O3 can be improved by increasing the stirring speed and friction area, and the tribocatalytic activity is significantly enhanced under ultrasonic vibration. The friction between Fe2O3 nanoparticles and the magnetic rod and Fe2O3 and the glass cup bottom plays key roles in the degradation of RhB, while the friction between Fe2O3 and water also makes a weak contribution. Catalytic mechanism investigations reveal that the friction-generated positive charges directly decompose dyes, but electrons first react with oxygen to generate superoxide (•O2–) radicals, and then •O2– participates in the degradation of dyes. This work expands the range of tribocatalysts and demonstrates that Fe2O3 is advantageous for its eco-friendliness, low cost, and high performance, which can act as a tribocatalyst for organic pollutant degradation through mechanical friction.