Interfacial Engineering Promoting Electrosynthesis Of Ammonia Over Mo/Phosphotungstic Acid With High Performance

Electrochemical nitrogen reduction reaction (eNRR) is recognized as a promising approach for ammonia synthesis, which is, however, impeded by the inert nitrogen and the unavoidable competing hydrogen evolution reaction (HER). Here, a Mo-PTA@CNT electrocatalyst in which Mo species are anchored on the fourfold hollow sites of phosphotungstic acid (PTA) and closely embedded in multi-walled carbon nanotubes (CNT) for immobilization is designed and synthesized. Interestingly, the catalyst presents a high ammonia yield rate of 51 +/- 1 mu g h(-1) mg(cat.)(-1) and an excellent Faradaic efficiency of 83 +/- 1% at -0.1 V versus RHE under ambient conditions. The concentrations of NH4+ are also quantitatively calculated by H-1 NMR spectra and ion chromatography. Isotopic labeling identifies that the N atom of the formed NH3 originates from N-2. The controlled experiments confirm a strong interaction between Mo-PTA and N-2 with an adsorption energy of 50.46 kJ mol(-1) and activation energy of 21.36 kJ mol(-1). More importantly, due to CNT's gas storage and hydrophobicity properties, there is a fourfold increase in N-2 content. The concentration of H2O is reduced by more than half at the interface of the electrode. Thus, the activity of eNRR can be significantly improved with ultrahigh electron selectivity.