Cobalt Nanoparticles Confined in Defective Carbon Matrices for Robust Intermittent CO2 Methanation.

The development of robust catalysts for CO2 methanation under intermittent operating conditions is key to harnessing renewable energy sources such as wind and solar. However, this pursuit faces two major obstacles. The heating-cooling cycles induce prolonged thermal stress, resulting in catalyst deactivation. Moreover, the temperature-sensitive selectivity hampers the ability to maintain high methane yield, leading to undesired by-products. Herein, we report cobalt nanoparticles confined within carbon matrices, which achieved 82.3% CO2 conversion and > 99% CH4 selectivity over multiple heating-cooling cycles toward intermittent CO2 methanation. The catalyst robustness arises from the low coefficient of thermal expansion and high thermal conductivity of the carbon matrix, which effectively mitigates thermal stress during temperature fluctuations. Mechanistic studies confirm that the reaction proceeds via a formate pathway, which contributes to the high CH4 selectivity across a wide temperature range. These insights provide a design framework for developing robust catalysts, advancing CO2 methanation performance, and the efficient use of fluctuating renewable energy sources.