Electrocatalytic N2 Fixation over Hollow VO2 Microspheres at Ambient Conditions

Electrochemical N-2 fixation has gained much attention as an environmentally friendly and sustainable process for NH3 production at ambient conditions. Its efficiency depends greatly on identifying highly active electrocatalysts with good stability. In this work, we propose the use of VO2 hollow microspheres as a robust non-precious metal catalyst for the N-2 reduction reaction (NRR). The catalyst operates efficiently and stably at neutral pH to high Faradaic efficiency (3.97%) and NH, yield (14.85 mu g h(-1) mg(cat)(-1)) under an applied potential of 0.7 V (vs. the reversible hydrogen electrode). Note that this catalyst also presents a high selectivity for NH, synthesis without N2H4 generation. Density functional theory reveals that the energetically favorable pathway for NRR is *N ->*NNH ->*NHNH ->*NHNH ->*NH2NH2 ->*NH2+NH3 ->*NH3+NH3 -> 2NH(3), where the first hydrogenation step to form NNH is the potential-determining step.