Mechanochemistry-driven CO2 conversion under mild conditions

Abstract

Mechanochemistry, increasingly regarded as a “fourth wave” of chemistry, provides a highly dynamic non-equilibrium route in which impact, shear, friction, and fracture concentrate energy within transient contact zones. By continuously renewing defect-rich interfaces and intensifying gas–solid mass transfer, mechanochemical processes can enable efficient carbon dioxide (CO₂) activation and conversion under mild conditions. This review surveys mechanochemistry-driven CO₂ conversion from a sustainability-oriented perspective and classifies existing studies into two mechanistically distinct regimes. First, we discuss non-sustainable mechanochemical routes, in which reactive solids (such as light-metal hydrides, hydrogen-storage alloys, alkaline-earth metals, silicate minerals, or stainless-steel milling media) serve as stoichiometric reagents and are consumed during CO₂ transformation. Second, we highlight sustainable mechanocatalytic pathways, where mechanical actions activate CO₂ over reusable catalysts and sustain closed catalytic cycles, as exemplified by Ru-, Ir-, Ni-based, and metal-free systems. Finally, we outline key challenges and future perspectives, focusing on quantitative energy accounting, operando identification of active sites and intermediates, product diversification beyond methanation, catalyst exploration, scalable reactor engineering, and artificial-intelligence-assisted catalyst and process optimization. In summary, these perspectives aim to guide the development of mechanochemistry-driven CO₂ conversion as a practical route toward carbon-neutral energy systems.