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.