Nanoporous B13C2 towards Highly Efficient Electrochemical Nitrogen Fixation

The electrochemical nitrogen fixation under mild conditions is a promising alternative to the current nitrogen industry with high energy consumption and greenhouse gas emission. Here, a nanoporous boron carbide (np-B13C2) catalyst is reported for electrochemical nitrogen fixation, which is fabricated by the combination of metallurgical alloy design and chemical etching. The resulting np-B13C2 exhibits versatile catalytic activities towards N-2 reduction reactions (NRR) and N-2 oxidation reaction (NOR). A high NH3 yield of 91.28 mu g h(-1) mg(cat.)(-1) and Faradaic efficiency (FE) of 35.53% at -0.05 V versus the reversible hydrogen electrode are obtained for NRR, as well as long-term stability of up to 70 h, making them among the most active NRR electrocatalysts. This catalyst can also achieve a NO3- yield of 165.8 mu g h(-1) mg(cat.)(-1) and a FE of 8.4% for NOR. In situ Raman spectroscopy and density functional theory calculations reveal that strong coupling between the B-C sites modulates the electronic structures of adjacent B atoms of B13C2, which enables the B sites to effectively adsorb and activate chemical inert N-2 molecules, resulting in lowered energy required by the potential-determining step. Besides, the introduction of carbon can increase the inherent conductivity and reduce the binding energy of the reactants, thus improving N-2 fixation performance.

Automated summary

The study introduces a nanoporous boron carbide catalyst for electrochemical nitrogen fixation, demonstrating high catalytic activity and stability. Through strong coupling between B-C sites, the catalyst is able to lower the energy required for activating inert N-2 molecules, resulting in improved nitrogen fixation efficiency.