Significantly enhanced electrocatalytic N2 reduction to NH3 by surface selenization with multiple functions

Abstract

The electrochemical N₂ reduction reaction (NRR) under ambient conditions is highly attractive. However, it is still a challenge to achieve a high NH₃ yield rate at low overpotential. Herein, we report RuO₂ nanoparticles with different degrees of surface selenation, which show excellent NRR performance at low overpotential. The NH₃ yield rate and FE of RuO₂–Se_0.18/C reach 12.97 μg h⁻¹ cm⁻² and 26.01% at −0.1 V vs. RHE, respectively, which is the highest NH₃ yield rate reported at low overpotential. The RuO₂–Se_0.18/C catalyst also shows excellent stability. The related NH₃ yield rate stays pretty constant after 50 h of electrolysis. The density functional theory (DFT) calculations show multiple promoted-synergism of surface selenation on the RuO₂ catalyst. First, optimized surface selenization could drive the adsorption of N₂ on RuO₂ sites. Second, surface hydrogenation promoted by surface selenization can suppress the hydrogen evolution reaction (HER, competitive reaction), enabling high NRR performance at low potential. Third, optimizing the surface selenization on RuO₂ can promote N₂ activation (*N₂ → *NNH). Fourth, surface selenization can promote NH₃ desorption (the rate-limiting step).