In2Cu3O6 Nanocluster in Siliceous Zeolite for Efficient CO2 Methanation

This work reports CO₂ methanation with high Faraday efficiency and production selectivity on In₂Cu₃O₆ nanoclusters encapsulated in siliceous MFI zeolite (In₂Cu₃O₆@zeolite) by modulating the pH and buffering capacity of electrolytes. Using an aqueous electrolyte of KHCO₃ and K₂CO₃ saturated with CO₂, the In₂Cu₃O₆@zeolite electrode achieves a superior electrocatalytic Faraday efficiency of 74.1% for CO₂ methanation and a retention rate of ∼90% after a 40 h long stability test. This represents one of the highest Faraday efficiency values for CO₂ methanation. In situ spectroscopic characterization of intermediates shows that the high selectivity for methanation in aqueous electrolytes is due to the enriched protonation and associated pH buffering effect enabled by the encapsulation of In₂Cu₃O₆ nanoclusters in MFI zeolite channels. When such an In₂Cu₃O₆@zeolite catalyst is used as the cathode of an aprotic Li-CO₂ battery, a high full-discharge capacity of 28,992 mAh g^–1 at 100 mA g^–1 and excellent cycling performance over 200 cycles at 400 mA g^–1 can be achieved.