Si-C atomic line achieving efficient electrocatalytic nitrogen reduction reactions

In this study, the concept of a Si-C atomic line (SCAL) featuring fully exposed atomic sites is introduced for the first time, and the SCAL serves as a highly efficient electrocatalyst for nitrogen reduction reactions (NRR). Thanks to the strong binding strength of the Si-C bonds (polar covalent bonds), the SCAL exhibits exceptional structural stability at 298.15 K. With a band gap of 1.86 eV characterized by a semiconductor, SCAL exhibits relatively high conductivity which is advantageous for electrocatalytic processes. N2 is adsorbed on the C sites in an end-on mode due to the most negative adsorption energy (–0.39 eV), and the nature of adsorption is s-p orbital hybridization. Based on the end-on N2 adsorption, the entire NRR pathway is simulated and shows a relatively low energy barrier of 0.50 eV, which is relatively low compared to reported metal-free NRR electrocatalysts. The charge transfer mechanism reveals that the active sites (C atoms) are responsible for charge transfer, while other parts of SCAL act as storage warehouses for charge. Moreover, SCAL demonstrates a preference for NRR over hydrogen evolution reaction (HER), underscoring its excellent electrocatalytic selectivity. This study opens new avenues for designing high-performance catalysts. [Display omitted] •The Si-C atomic line is established for the first time.•The SCAL shows fully exposed atomic sites, high stability and high conductivity.•As an NRR electrocatalyst, the SCAL presents a low energy barrier of 0.5 eV.•SCAL demonstrates a preference for NRR over HER, demonstrating excellent selectivity.•The charge transfer mechanism is revealed during NRR.