Rational Design of Transition Metal–Phosphorus Dual-Atom Catalysts in Defective h-BN for CO2 Hydrogenation and Cycloaddition

Dual-atom catalysts (DACs) have emerged as a promising platform for converting CO2 into valuable chemicals, addressing critical energy and environmental challenges. Here, we theoretically designed M1-P1/VBN catalysts by embedding single transition metal (M = Ir, Rh, and Co) and phosphorus atoms into defective h-BN. Extensive first-principles calculations were employed to investigate the mechanisms of CO2 thermal hydrogenation to HCOOH and CO2 cycloaddition with propylene oxide (PO) to produce propylene carbonate (PC). The metal-phosphorus dual-active sites were predicted to facilitate simultaneous activation and adsorption of CO2, H2, and PO, enabling detailed exploration of the reaction pathways. By combining static electronic structure calculations and microkinetic simulations, this work demonstrates that M1-P1/VBN sheets show excellent catalytic performance for both reactions under relatively mild conditions, particularly for CO2 hydrogenation on Co1-P1/VBN and cycloaddition on Rh1-P1/VBN. Stability analysis confirms the robustness of transition-metal-doped M1-P1/VBN systems. Notably, the binding strength of small molecules strongly correlates with metal type, and a strong linear correlation was observed between the adsorption free energies of reactive intermediates. This study offers valuable theoretical insights into the thermocatalytic mechanisms of CO2 hydrogenation and cycloaddition mediated by M1-P1/VBN catalysts, laying a foundation for designing multifunctional DACs to advance CO2 utilization technologies.