Isoelectric Si Heteroatoms as Electron Traps for N₂ Fixation and Activation

Doping the host materials with either electron-rich heteroatoms or electron-deficient heteroatoms have been applied as a straightforward and main-stream method to modify the electronic structures and boost the electrochemical activity for various reactions, including nitrogen reduction reactions (NRR). As the third type of dopants, isoelectric heteroatoms (exemplified with Si atoms in carbon framework in this work) have been designed as highly efficient active centers for NRR. As the same group element with a different size and electronegativity to carbon support, the isoelectric Si heteroatom (Iso-e Si) creates localized singularities with a lone orbital that can act as an electron trap for pre-adsorbed N₂ molecules through coulomb interaction and thus facilitates the following activation process for NRR. Iso-e Si atom thus functions as a special type of metal-free single atom-based electrocatalyst to largely boost the faradaic efficiency of pristine carbon support for NRR by a factor of 12, giving a remarkably high turnover frequency value of 0.52 h⁻¹, comparable to atomically dispersed transition metal-based electrocatalysts.