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.