Evolutionary mechanism of particulate matter degradation by non-thermal plasma

Particulate matter (PM) emitted by power machinery severely harms air quality and ecological balance, making the development of efficient and green PM-removal technologies a key global environmental challenge. This work built a visualization system for diesel engine PM decomposition via non-thermal plasma (NTP), conducting multi-stage NTP oxidation at 120°C to clarify reaction pathways. The results demonstrate that NTP significantly influences the microcrystalline reconstruction and chemical evolution of PM. Early oxidation removes surface short crystallites, increasing crystallite length, reducing tortuosity, narrowing D1 peak, and boosting graphitization. Mid-stage sees NTP active substances penetrate inside, shortening crystallites and regularizing structure. Late-stage primary particles form “hollow shells” with few long crystallites, and order/graphitization rises again. Chemically, NTP reduces high-carbon components while increasing low-carbon ones in PM soluble organics, decomposes C=C bonds to form oxygen-containing groups, enhances PM oxidation activity, weakens π* peaks, and strengthens σ* peaks, clearly confirmed by the carbon K-edge electron energy loss spectra. This study clarifies the mechanistic pathways of NTP-driven PM decomposition, supporting clean energy advancement and atmospheric governance.