Capture-Backdonation-Recapture Mechanism for Promoting N2 Reduction by Heteronuclear Metal-Free Double-Atom Catalysts

Facing the increasingly serious energy and environmental crisis, the development of heteronuclear metal-free double-atom catalysts is a potential strategy to realize efficient catalytic nitrogen reduction with low energy consumption and no pollution because it could combine the advantages of flexible active sites in double-atom catalysts while also being pollution-free and have high Faraday efficiency in metal-free catalysts simultaneously. However, according to the existing mechanism, the finite orbits of other nonmetallic atoms, except the boron atom, reduce the possibility of metal-free catalysis and hinder the development of heteronuclear metal-free double-atom catalysts. Herein, we propose a new capture-backdonation-recapture mechanism, which skillfully uses the electron capture-backdonation-recapture between boron, the substrate, and other nonmetallic elements to solve the above problems. Based on this mechanism, by means of the first-principle calculations, the material structure, adsorption energy, catalytic activity, and selectivity of 36 catalysts are systematically investigated to evaluate their catalytic performance. B-Si@BP1 and B-Si@BP3 are selected for their good catalytic performance and low limiting potentials of -0.14 and -0.10 V, respectively. Meanwhile, the capture-backdonation-recapture mechanism is also verified by analyzing the results of adsorption energy and electron transfer. Our work broadens the ideas and lays the theoretical foundation for the development of heteronuclear metal-free double-atom catalysts in the future.

Automated summary

In this study, a new capture-backdonation-recapture mechanism is proposed to solve the issues in the development of heteronuclear metal-free double-atom catalysts. Based on this mechanism, the material structure, adsorption energy, catalytic activity, and selectivity are systematically investigated to evaluate the performance of 36 catalysts. B-Si@BP1 and B-Si@BP3 are selected as promising catalysts with good catalytic performance and low limiting potentials. The results also verify the validity of the capture-backdonation-recapture mechanism. This work expands the ideas and lays the theoretical foundation for future development of heteronuclear metal-free double-atom catalysts.