Efficient Asymmetrical Silicon-Metal Dimer Electrocatalysts for the Nitrogen Reduction Reaction.

The electrocatalytic nitrogen reduction reaction (ENRR) has been regarded as an eco-friendly and feasible substitute for the Haber-Bosch method. Identifying the effective catalysts for the ENRR is an extremely important prerequisite but challenging. Herein, asymmetrical silicon-metal dimer catalysts doped into g-C3N4 nanosheets with nitrogen vacancies (SiM@C3N4) were designed to address nitrogen activation and reduction. The concept catalysts of SiM@C3N4 can combine the advantages of silicon-based and metal-based catalysts during the ENRR. Among the catalysts investigated, SiMo@C3N4 and SiRu@C3N4 exhibited the highest activities towards the ENRR with ultra-low onset potentials of -0.20 and -0.39 V; meanwhile, they suppressed the competing hydrogen evolution reaction (HER) due to the relative difficulty in releasing hydrogen. Additionally, SiRu@C3N4 is demonstrated to possess strong hydrophobicity, which is greatly beneficial to the production of ammonia. This research provides insights into asymmetrical silicon-metal dimer catalysts and reveals a new method for developing dual-atom electrocatalysts. This asymmetrical dimer strategy can be applied in other electrocatalytic reactions for energy conversion.