Shielded bifunctional nanoreactor enabled tandem catalysis for plasma methane coupling

The direct conversion of methane into valuable unsaturated C₂ hydrocarbons (C₂H₂ and C₂H₄) attracts growing attention. Non-thermal plasma offers a promising approach for this process under mild conditions. However, the competing formation of C₂H₆ and excessive dehydrogenation limit the selectivity toward C₂H₂ and C₂H₄. Herein, we develop a promising shielded bifunctional nanoreactor with a hollow structure and mesoporous channels (Na₂WO₄-Mn₃O₄/m-SiO₂) that effectively limits CH₄ overactivation and promotes selective coupling to form C₂H₂ and C₂H₄ under plasma activation, achieving 39% CH₄ conversion with 42.3% C₂H₂ and C₂H₄ fraction. This nanoreactor features isolated Na₂WO₄ embedded within the channels and Mn₃O₄ confined in the cavity of the SiO₂ hollow nanospheres, enabling internal tandem catalysis at co-located active sites. Na₂WO₄ induces the conversion of diffused CH₄ and CH₃ into reactive intermediates (^*CH and ^*CH₂), which subsequently couple on the Mn₃O₄ surface to form C₂H₂ and C₂H₄. Furthermore, the mesoporous channels inhibit the plasma discharge within the nanoreactor, preventing deep dehydrogenation of CH_x species to solid carbon. This nanoreactor demonstrates a highly selective route for the nonoxidative conversion of methane to valuable C₂ hydrocarbons, offering a new paradigm for the rational design of catalysts for plasma-driven chemical processes.