Formaldehyde degradation by soft-sliding-electrification-induced air ionization

Formaldehyde (HCHO), a highly toxic and carcinogenic gas, is the most common indoor air pollutant and a threat to human health. Developing simple and effective technological routes to achieve sustainable degradation of HCHO has become a common goal. In this work, we reported a self-powered air-ionized HCHO degradation system based on a soft-sliding freestanding mode triboelectric nanogenerator (SSF-TENG). The sliding-electrification process between soft rabbit fur and a robust PTFE film enables the generation of electrical outputs of up to ten thousand volts that can trigger air breakdown. The generated O₃, ·OH and other highly oxidizing substances could degrade HCHO into CO₂ and H₂O. Through a standard ball gap platform based on two hollow Cu balls, the voltage of air discharge was measured to be between 11.2 kV and 14.4 kV. For demonstration, the SSF-TENG was applied to two parallel disk-shaped Cu electrodes to continuously breakdown the air with a peak discharge current of 6 mA. The system can produce a maximum O₃ concentration of 1.2 ppm within 50 minutes. Moreover, the HCHO concentration can be reduced from 1.6 ppm to 0 within 20 minutes, and the degradation speed reaches 0.08 ppm/min. This work highlights the application of triboelectric microplasma in pollutant removal, which has great potential in self-powered environmental purification.