Self-powered exhaust gas purification by negative ions and photoelectric catalysis based on triboelectric nanogenerator

Industrial exhaust gas emissions have caused many environmental problems such as particulate matter (PM) pollution and volatile organic compounds (VOCs) emissions, seriously endangering human's health. Here, we demonstrate a new method for air purification and degradation of VOCs based on synergetic effects of electric-assisted photocatalysis and negative air ions generated by direct-current triboelectric nanogenerators (DC-TENG). The negative electrode of DC-TENG is connected to carbon fiber bundle (CFB) to generate negative air ions, while the positive electrode of DC-TENG is connected to dust collection board loaded with catalyst and can provide a bias electric field for photocatalysis, allowing VOCs to be adsorbed onto the collection board and accelerating the efficiency of photocatalytic degradation. Under the driving of DC-TENG, 1.1 × 1013 negative ions are generated by CFB per second, which can reduce PM2.5 concentration in a sealed box from 999 μg·m−3 to less than 50 μg·m−3 within 80 s. The proposed system combining negative ions and photoelectric catalysis can reduce formaldehyde concentration from 1.97 ppm to 0 ppm in 12 min, which is 2.4 times higher than the degradation rate of photocatalysis alone. This air purification system demonstrated here not only harvests the wasted environmental energies but also proposes a new strategy to sink particulate matter and degrade VOCs in the air, demonstrating a cleaner, more efficient, multifunctional, and self-powered exhaust gas treatment system that can provide new solutions for future air purification.