Gold-Modified Mo2C Nanoparticles Supported on Nitrogen-Doped Carbon Nanotubes for Electrochemical Nitrogen Fixation

Electrochemical N-2 reduction reaction ( NRR) provides an alternative approach to producing ammonia (NH3) under ambient conditions. However, the sluggish kinetic process and existence of the competitive reaction of hydrogen evolution reaction make the catalytic activity and selectivity of NRR catalysts still very low. To tackle this challenge, gold-modified molybdenum carbide (Mo2C) nanoparticles (NPs) supported on nitrogen-doped carbon nanotubes (Au/Mo2C/NCNTs) was synthesized using a strategy that combines laser irradiation and carbothermal reaction. For such a composite, pony-sized Mo2C nanocrystals play important roles in cleavage of the N.N bond and the occurrence of N-2 adsorption, while Au NPs promote charge transfer and intermediate protonation to enhance the selectivity of NRR. Using these advantages, the NH3 yield rate and Faradaic efficiency of Au/Mo2C/NCNTs reached 46.89 mu g mg(cat.)-1 h(-1) and 2.78% at -0.3 V versus reversible hydrogen electrode, which were 2.36 and 3.20 times those of Mo2C/NCNTs, respectively. Our effort provides a unique pathway for preparing Au/Mo2C/NCNTs composites and gives insight into the mechanism of the NRR performance enhanced by metal NP loading and heteroatom doping.