High-Performance Nitrogen Fixation over Mo Atom Modified Defective α-MnO2 (001)

The production of ammonia under ambient conditions through electrocatalytic nitrogen reduction reaction is significant but challenging. The lack of an available active NRR electrocatalyst with a high selectivity impedes the development of the electrochemical ammonia synthesis. In this work, via first-principles density functional theory calculations, we investigated various transition metal atoms (Fe, Cr, V, and Mo) substitution modified defective (with an oxygen vacancy) alpha-MnO2(001) as NRR electrocatalyst. It was found that the incorporation of a single Mo atom substituent at Mn site of alpha-MnO2(001) shows the best performance of nitrogen fixation through enzymatic mechanism with a favorable limiting potential of -0.14 V. The superior selectivity for NH(3)over H(2)is observed with high Faradaic efficiency of 99 %. The dz2-like characteristics of occupied states around the Fermi level of Mo active center maximizes thep-dorbital hybridization and thus promotes the stabilities of *N(2)and *N2H, which leads to the superior NRR performance. These findings provide theoretical guidance to the development of highly efficient NRR electrocatalysts via defect engineering.