Mechanochemical carbon dioxide capture and conversion.

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