Mechanism-Guided Selective Hydrogenation of CO2 to Light Olefins: DFT-Informed Microkinetics and Surface Electronic Regulation Under Green Hydrogen Scenarios

Achieving high selectivity in the hydrogenation of CO2 to light olefins remains challenging because of the complex reaction network and the difficulty of regulating key intermediates. Motivated by green-hydrogen-enabled power-to-chemicals pathways, we combine density functional theory (DFT) with first-principles microkinetic simulation (FPMS) to construct a quantitatively predictive reaction-energy landscape and elucidate structure–selectivity relationships. A comprehensive reaction network is established through energy-surface fitting, and steady-state rate constants are solved to capture the microkinetic competition between elementary steps. By introducing electronic density-of-states (DOS) modulation as a design variable, we directly correlate surface structural parameters with rate-controlling steps, thereby enabling targeted regulation of C–C coupling and hydrogen transfer processes. The calculated barrier for CO2 adsorption to COOH* is 1.35 eV, while the transition state barrier for C–C coupling is 1.50 eV, corresponding to a reaction rate of 9.7 × 103 s−1; the olefin desorption rate reaches 1.7 × 107 s−1. Crucially, shifting the d-band center from −2.35 eV to −1.60 eV increases the C2–C4 olefin selectivity from 42.6% to 68.3%, establishing an actionable electronic structure lever for catalyst optimization. These results reveal the intrinsic mechanism by which surface electronic and geometric regulation governs intermediate stabilization and rate control, providing a verifiable, mechanism-based design principle for efficient CO2-to-olefin catalysts aligned with green hydrogen deployment.