Plasma-Driven Catalyst-Free CO 2 Conversion into Salicylic Acid at the Gas–Liquid Interface

Efficient CO2 conversion into high-value products is essential for addressing climate change. Despite advances in CO2 reduction, many existing methods rely on catalysts, reactive reactants, and conventional nucleophilic pathways, leaving room for more versatile, eco-friendly approaches. Here, we present a plasma-driven, catalyst-free strategy utilizing superacid chemistry within microdroplet reactors to convert CO2 into valuable products. By using CO2 as the nebulization gas, we successfully incorporate it into inert benzene to produce salicylic acid. Unlike traditional CO2 conversion mechanisms, our approach uses plasma to protonate CO2 based dominantly on plasma generated (H2O)2•+ and complementarily on its hydrolysis product, generating a highly reactive intermediate that facilitates subsequent nucleophilic reactions. This novel mechanism, validated by tandem mass spectrometry, isotopic labeling, and density functional theory calculations, highlights the crucial role of superacid formation and enrichment at the nonaqueous droplet interface in boosting reactivity. Additionally, we demonstrate that the reaction predominantly occurs at the droplet surface, with parameters such as flight distance and nebulization pressure enabling precise control over interfacial dynamics and reaction pathways. This work introduces a transformative strategy for CO2 utilization, showcasing the vast potential of microdroplet interfaces and plasma-driven superacid chemistry in revolutionizing sustainable carbon capture and chemical conversion.