Plasma-surface interaction mechanisms for CO2 recycling

CO2 recycling by plasma is one of the major applications of cold plasmas for a sustainable world, whether for methanation, methanol synthesis, or dry reforming of methane. Like all gas conversion processes using cold plasmas, these technologies rely on the advantages of non-equilibrium thermodynamic chemistry, making optimal use of radicals or vibrational and electronically excited states produced by the plasma. However, they must also address the same challenges regarding product selectivity and energy efficiency. To tackle these issues, several solutions are being explored: (i) the most traditional approach is to combine the plasma with catalysts but recently other possibilities have been investigated, such as (ii) association with ionic membranes or (iii) liquid solvents. Regardless of the chosen solution, the optimization of these technologies primarily suffers from a lack of data on the fundamental mechanisms. Thanks to reactors specifically dedicated to fundamental studies (pulsed RF and Glow discharge) and the implementation of in situ time-resolved diagnostics, a better understanding of the plasma-surface interaction mechanisms at the core of these technologies can be obtained. With this data, kinetic models that incorporate both gas-phase and adsorbed-phase processes are beginning to be developed with systematic experimental validation.