Disentangling metallic cobalt sites and oxygen vacancy effects in synergistic plasma-catalytic CO2/CH4 conversion into oxygenates

Plasma-catalysis is a highly promising renewable-energy-based solution for decarbonization of industrial and environmental catalysis. However, urgent insights how to develop plasma-specific catalysts and synergize with the unique plasma effects are vitally needed for CO 2 /CH 4 utilization. Herein we provide guiding principles for catalysts design enabling discriminative production of liquid oxygenates. Comprehensive tests revealed that metallic Co was critical to enhance the CH 3 COOH generation, while oxygen vacancies (O v ) contributed to the formation of CH 3 OH. The gaseous and interfacial simulations verified the strong chemisorption of CO 2 and key O-containing radicals (O, OH, COOH) on O v , thereby shifting the reaction from high-barrier surface to the gas phase via the barrierless Eley-Rideal mechanism. The specifically O v -assisted pathways for R-COOH/R-OH generation over the custom-designed Co-MgAlO-O v multiphase structures are proposed. This study confirms that the microstructure design can modulate the radical adsorption and kinetic factors of the plasma-induced interfacial catalysis leading towards the plasma-electrified energy conversion. Co-MgAlO-O v , a multiphase microstructure made of highly-dispersed Co nanoparticles, alkaline MgO promoter and O v -rich defects, is in-situ fabricated on Nickel Foam assisted by Ar plasma modification, showing excellent catalytic activity and sustainability for plasma-driven CO 2 /CH 4 conversion, as well as the discriminative production of acids and alcohols. We verified that metallic Co was critical to enhance the generation of CH 3 COOH, while oxygen vacancies (O v ) contributed to the formation of CH 3 OH. The comprehensive in-situ DRIFTS tests, plasma kinetic modelling and DFT calculations demonstrate the strong chemisorption of CO 2 and key O-containing radicals (O, OH, COOH) on O v , thereby undergoing the dominant Eley-Rideal mechanism, which is completely different from common thermal-catalysis. • Plasma-enabled CO 2 /CH 4 conversion using custom-designed Co-based catalysts. • Basic sites, metallic Co, and oxygen vacancies O v synergistically increase CO 2 /CH 4 conversion. • Multiphase Co-MgAlO-O v structure greatly improved the oxygenates selectivity. • Co is critical to CH 3 COOH formation, while O v controls CH 3 OH generation. • New O v -assisted reaction pathways are proposed for synergistic plasma-catalysis.