Plasma-Enabled Active Site Regeneration for Selective Liquid Fuel Production across Catalyst Binding Regimes in CH4-CO2 Conversion

The selective conversion of CH4 and CO2 to liquid fuels is constrained in thermal catalysis by linear scaling relationships, overoxidation of oxygenate intermediates, and irreversible surface poisoning. Nonthermal plasma-enabled catalysis circumvents some of these limitations by introducing non-equilibrium excitation (e.g., vibrational, electronic, and dissociative) of molecular reactants. However, performance remains hindered by catalyst deactivation due to carbon and oxygen accumulation on active sites, driven by distinct mechanisms tied to metal-adsorbate interactions. Here, we show how continuous active-site regeneration during plasma-catalysis can be achieved by coupling plasma-driven dissociative chemisorption with targeted co-reactant activation. This strategy enables selective removal of surface poisons and is applicable across distinct catalyst regimes. On weakly binding catalysts like Cu, plasma-generated species remove adsorbed oxygen atoms, restore CH3O* intermediates and triple methanol selectivity. On strongly binding catalysts like Ni, accumulated CHx* fragments are selectively removed, doubling C2 hydrocarbon yields by reactivating C-C coupling. Unlike thermal systems, plasma excitation decouples regeneration from equilibrium constraints that correlate adsorption and desorption kinetics to a single gas temperature, enabling continuous, in situ removal of poisons without cycling and disrupting steady-state conversion. Using a combination of surface characterization methods and density functional theory calculations, we identify the mechanism by which plasma-co-reactant synergy tunes surface intermediates and redefines the design space of heterogeneous catalysis under mild conditions (Tsur = 473 K, Tvib = 4200 K, p = 1 atm).