Rhodium-molybdenum oxide electrocatalyst with dual active sites for electrochemical ammonia synthesis under neutral pH condition

Abstract

Electrochemical nitrogen reduction reaction (NRR) process has attracted significant attention recently as an alternative route for green ammonia (NH3) production to replace conventional, energy intensive Haber-Bosh process. However, a major challenge in NRR process is the relatively poor selectivity of NRR process over its competing hydrogen evolution reaction (HER) process. Herein, we report the synthesis of molybdenum oxide decorated on the rhodium (RhMoOx/C) catalyst for an efficient NRR with high selectivity. RhMoOx/C catalyst exhibits an outstanding NH3 yield rate of 57.2 μg h−1 mgcat−1 at −0.6 V vs. RHE and a high faradaic efficiency of 22% at −0.2 V vs. RHE in 0.1 M Na2SO4 electrolyte. This study reveals the interdependent relationship between the catalyst structure, operating conditions, and the reaction selectivity in the electrochemical NH3 synthesis. Moreover, this study also demonstrates the effectiveness of the bimetallic materials in enhancing the NRR process which is an important finding for designing a future electrocatalyst for electrochemical NH3 production.