Plasma‐Assisted CO2 Reduction into Nanocarbon in Water Using Sonochemically Dispersed Liquid Gallium

Abstract Carbon dioxide is a greenhouse gas that contributes to global warming but fortunately can be removed via chemical conversion processes that often involve a reduction step. Dielectric barrier discharge (DBD) plasma is an effective way to promote chemical reduction processes but requires a catalyst for energetically demanding reactions. In this study, the rapid conversion of CO 2 into solid carbon via a DBD plasma is reported using dispersed liquid metal Ga which is first converted into GaOOH particles to ultimately form a GaOOH/C nanocomposite. Raman and X‐ray diffraction (XRD) experiments indicate that amorphous activated carbon is formed after the plasma treatment. Further analysis demonstrates that highly dispersed sub‐nano‐sized carbon particles containing oxygen functional groups are formed uniformly on the GaOOH surface. The CO 2 conversion mechanism suggests that plasma electrons activate CO 2 molecules, while plasma‐generated oxygen vacancies on the catalyst surface help dissociate CO 2 into solid carbon. This work opens a new approach for synthesizing materials comprising of highly dispersed sub‐nano‐sized carbon on a metal oxide support suitable for other applications such as adsorption, heterogenous catalysis, and energy conversion.