Breaking-up CO₂ by Redox Reaction with Rhenium at High Pressure*

Over the past several decades, extensive research has been made in carbon capture and sequestration (CCS) to mitigate the rising amount of carbon dioxide (CO₂) in the atmosphere. Because of its high thermal stability, the CO₂ molecule is highly resistant to decomposition even at temperatures above 2000 K, making direct dissociation of CO₂ an inefficient approach to carbon sequestration. High pressure may facilitate the reduction of CO₂ at lower temperatures, as recently demonstrated in the CO₂-Re system between pressures of 8-48 GPa and temperatures as low as 1500K. In this study, the redox reaction between CO₂ and Re is investigated at high pressures (8-20 GPa) and temperatures (300K-4000K) via ab initio molecular dynamics simulations based on density functional theory. At high temperatures, CO₂ molecules break apart in the presence of Re atoms. Radial distribution functions (RDFs) provide strong evidence for Re-O and C-C bonding, which are stable upon quenching the system to room temperature. These results show that high pressure redox reactions with Re and other transition metals may provide a unique pathway to irreversible decomposition of the CO₂ molecule into solid carbon (graphite or diamond).