Alloying of Cu with Ru Enabling the Relay Catalysis for Reduction of Nitrate to Ammonia.

Abstract

Involving eight electron transfer process and multiple intermediates of nitrate reduction reaction (NO3 RR) leads to a sluggish kinetic and low Faradic efficiency, therefore, it's essential to get an insight into the reaction mechanism to develop highly efficient electrocatalyst. Herein, a series of reduced graphene oxide supported RuCu alloy catalysts (Rux Cuy /rGO) were fabricated and used for the direct reduction of NO3 - to NH3 . It is found that the Ru1 Cu10 /rGO shows the ammonia formation rate of 0.38mmol cm-2 h-1 (loading 1mg/cm2 ) and the ammonia Faradic efficiency (FE) of 98% under an ultralow potential of -0.05V versus RHE, which is comparable to Ru catalyst. The highly efficient activity of Ru1 Cu10 /rGO can be attributed to the synergetic effect between Ru and Cu sites via a relay catalysis, in which the Cu shows the exclusively efficient activity for the reduction of NO3 - to NO2 - and Ru exhibits the superior activity for NO2 - to NH3 . In addition, the doping of Ru into Cu tunes the d-band center of alloy and effectively modulates the adsorption energy of the NO3 - and NO2 - , which promotes the direct reduction of NO3 - to NH3 . This synergetic electrocatalysis strategy opens a new avenue for developing highly efficient multifunctional catalysts. This article is protected by copyright. All rights reserved.