Methanol-Mediated Electrosynthesis of Ammonia

Abstract

The development of electrochemical nitrogen reduction reaction (NRR) to ammonia currently faces the dilemma of low Faradaic efficiency (FE) due to the competing hydrogen evolution reaction (HER). The proton-donating ability of proton donor at the electrode–electrolyte interface plays a critical role in inhibiting HER and then boosting the selectivity of NRR. Depending on the intrinsic discrepancy of proton-donating ability between alcohol and water, herein, we demonstrate an innovatively well-controlled alcohol–water electrolyte system to modulate local proton concentration and the microenvironment at the electrode–electrolyte interface, wherein the availability and dissociation process of water can be substantially restricted, accompanied by an expanded electrochemical window and inhibited HER. In particular, the methanol-enabled electrolyte presents a record high NRR FE of 75.9 ± 4.1% and ammonia yield rate of 262.5 ± 7.3 micrograms per hour per milligram of catalyst (FeOOH/CNTs), indicative of ∼8-fold enhancements compared with that in conventional aqueous electrolytes and the universality over the other catalysts.