Highly Efficient Methane Electrosynthesis Enabled by Precise, Multifaceted Interface Regulation.

The electrocatalytic reduction of carbon dioxide (CO2) offers a pathway to transform greenhouse gas emissions into fuels and chemicals using renewable electricity. Among possible products, methane (CH4) is particularly attractive due to its high energy density and seamless integration with existing natural gas infrastructure, yet its electrosynthesis is hindered by demanding multi-electron kinetics and mass-transport constraints. Here, we report a four-channel copper tubular penetration electrode (TPE) with a honeycomb-like architecture that fundamentally reshapes the reaction environment for CO2 electroreduction. By precisely controlling electrode cross-sectional thickness, this multi-channel design regulates gas, electron, and electrolyte transport, stabilizing the three-phase interface required for efficient CH4 formation. The optimized TPE achieves a CH4 Faradaic efficiency of 87.5%, a half-cell energy efficiency of 43.46%, and stable operation for 100 hours. Combined experimental and theoretical analyses reveal that rational design of electrode architecture enables precise control over the CO2 adsorption configurations and reaction intermediates, thereby fine-tuning the reaction pathway toward CH4. These findings establish multi-channel TPEs as a powerful platform for efficient CO2 electromethanation.