Mechanochemical carbon dioxide capture and conversion

Developing a direct carbon dioxide (CO₂) capture and methanation method is one of the most important challenges to achieving carbon neutrality. However, converting CO₂ into methane (CH₄) kinetically requires the activation of stable CO₂ at high temperatures (300-500 °C), while the CO₂-to-CH₄ conversion thermodynamically favours low temperatures. Here we report an efficient mechanochemical CO₂ capture and conversion under mild conditions (65 °C). Using commercial zirconium oxide (ZrO₂) and nickel catalysts, the mechanochemical CO₂ capture capacity was 75-fold higher than the conventional thermochemical process. The mechanochemical CO₂ conversion reached a nearly quantitative CO₂ conversion (99.2%) with CH₄ selectivity (98.8%). We determined that repeatedly induced abundant oxygen vacancies on ZrO₂ by dynamic mechanical actions are responsible for efficient CO₂ capture and, thus, subsequently spontaneous methanation.