Recycling PM_2.5 carbon nanoparticles generated by diesel vehicles for supercapacitors and oxygen reduction reaction

Particulate matter (PM) pollution has become a serious environmental problem, especially in developing countries, owing to its severe threat to human health. Particularly, airborne PM_2.5 (mean aerodynamic diameter ≤2.5 µm) particles are extremely harmful, because the tiny particles can enter human respiratory system and even penetrate into circulatory system. Herein, we propose an effective strategy to recycle PM_2.5 carbon nanoparticles generated by diesel vehicle engine for the applications of clean energy. After thermal treatment and purification, the PM_2.5 derived carbon nanoparticles show a diameter distribution between 25 and 40 nm, mesoporous characteristics (with an average pore size of ~3.3 nm), and homogeneous nitrogen incorporation (with N content of ~1.1 at%). The PM_2.5 derived N-doped mesoporous carbon nanoparticles were used as an advanced electrode material in supercapacitors, exhibiting excellent specific capacity and superb stability over long-term cycling. Moreover, the recycled PM_2.5 carbon nanoparticles show attractive electrocatalytic properties for oxygen reduction reaction, presenting high onset potential and good immunity to methanol crossover. We expect this research can provide inspiration for air pollution control and sustainable energy utilization.