Efficient CO ₂ Capture and In Situ Electrocatalytic Conversion on Heavy Metal-Doped Graphene Surface: A Comprehensive DFT Study

The recovery of heavy metals and the capture and conversion of CO2 are both highly energy-intensive processes. Nevertheless, they exhibit considerable synergistic potential, and integrating these technologies presents a promising approach for improving environmental sustainability while lowering operational costs. In this study, we utilized density functional theory (DFT) calculations to elucidate the mechanism through which nitrogen-doped graphene (NG) surfaces simultaneously capture five heavy metal atoms from coal-fired power plant flue gas and catalyze the in situ electrochemical reduction of CO2 to CH3OH and CH4. Calculations of electronic properties reveal that the NG surface exhibits strong binding affinity toward all investigated heavy metals except Hg. Analysis of reaction pathways indicates that Cd@C–N4 demonstrates the minimal overpotential (0.32 eV) among the examined systems. This study, underpinned by density functional theory calculations, illustrates the feasibility of simultaneously attaining heavy metal recovery and electrocatalytic CO2 reduction. Additionally, it offers a theoretical framework for employing NG adsorbents to capture and stabilize heavy metals in coal-fired power plants, along with their subsequent use for in situ CO2 electrocatalysis.