Biomimetic Gas-Trapping Electrode Toward N2 Electrofixation

Abstract

This work has been inspired by water striders’ hair structures, developing a class of gas self-storage electrodes for trapping N₂ for electrofixation. The electrode is comprised of nickel phosphides encapsulated by phosphorus-doped carbon shells, showing simultaneous “superaerophilic” and “superhydrophobic” domains on the surfaces with an underwater N₂ contact angle of 13.4° and water contact angle of 140.7°. Through mechanism studies combining molecular dynamics (MD) and density functional theory (DFT) simulations, it shows the superaerophilic domains that contribute to enriching N₂ at the electrode/electrolyte interfaces for favorable gas feedstock supply, while superhydrophobic domains suppressing competitive hydrogen evolution. Benefit from the directly trapping N₂ molecules, the electrode drives right shift of the reaction equilibrium with substantially increased Faradic efficiency up to 42.4%, rating it among the most efficient nitrogen electrofixation catalysts in aqueous electrolytes. The present finding is expected to provide an additional dimension to biomimetic mechanisms that manipulate systems beyond traditional constraint.