Solvent-free mechanochemical conversion of CO₂ into mesoporous SiC: a green route to high-performance catalysts

Silicon carbide (SiC) is a critical material across structural, electronic, and catalytic applications; however, its conventional synthesis via the Acheson process is highly energy-intensive, operating at 2200–2400 °C with low carbon efficiency. Herein, we report a novel, solvent-free mechanochemical synthesis of mesoporous SiC using CO₂ as a sustainable carbon feedstock and SiO₂/Mg as earth-abundant precursors. Through a two-step ball-milling process, SiO₂ is first reduced by Mg to form Mg₂Si, which then spontaneously reacts with CO₂ to form SiC and MgO, achieving a high CO₂ conversion efficiency of 84% at only 10% of the energy cost of conventional methods. Density functional theory (DFT) calculations confirm the thermodynamic feasibility of CO₂ activation on Mg₂Si. The produced mesoporous SiC exhibited excellent durability and served as a highly stable support for Ni catalysts in dry reforming of methane (CH₄ + CO₂ → H₂ + CO), maintaining performance over 100 hours with minimal coke formation. This work introduces a green, scalable route for synthesizing high-value SiC, integrating CO₂ utilization and catalyst development under the principles of green chemistry.