From pollution to wealth: Soot-graphene hybrid structure as supercapacitor electrode for high-performance alternating current filtering

Efficiently employing air pollution substances as functional materials cannot only realize recycling environmental wastes into wealth, but also alleviate the air pollution and respiratory disease problems. Herein, we report a soot-graphene hybrid structure as supercapacitor electrode materials for achieving good alternating current (AC) filtering performances. Soot particles, which cause environmental pollution, can be readily renewable from daily combustion wastes with abundant natural resources, enabling fast electrolyte-ion migration on their surface. Graphene can be grown from either methane or renewable peanut oil to reduce interfacial resistance between soot and current collector, assisting in making the most of structural advantages of soot. The synergistic effect offers supercapacitor with good frequency-response ability and AC filtering performances in both aqueous and organic electrolytes: high impedance phase angle of −80.7° and high energy density of 509 μF V² cm⁻² at 120 Hz, short RC time constant of 0.213 ms, excellent electrochemical stability, as well as a good ability for filtering AC signals with different waveforms into direct current signals. This study offers a sustainable strategy to recycle environmental pollution into value-added electrode materials for high-performance AC filtering supercapacitors, which displays promising potential in eco-friendly and cost-effective development of small-volume AC filters for miniaturized electronics.