Efficient Nitrogen Fixation to Ammonia through Integration of Plasma Oxidation with Electrocatalytic Reduction.

Abstract

Present one-step N2 fixation is impeded by tough activation of the N≡N bond and low selectivity to NH3 . Here we report fixation of N2 -to-NH3 can be decoupled to a two-step process with one problem effectively solved in each step, including: 1) facile activation of N2 to NOx - by a non-thermal plasma technique, and 2) highly selective conversion of NOx - to NH3 by electrocatalytic reduction. Importantly, this process uses air and water as low-cost raw materials for scalable ammonia production under ambient conditions. For NOx - reduction to NH3 , we present a surface boron-rich core-shell nickel boride electrocatalyst. The surface boron-rich feature is the key to boosting activity, selectivity, and stability via enhanced NOx - adsorption, and suppression of hydrogen evolution and surface Ni oxidation. A significant ammonia production of 198.3 μmol cm-2 h-1 was achieved, together with nearly 100 % Faradaic efficiency.