Mn3O4 nanoparticles@reduced graphene oxide composite: An efficient electrocatalyst for artificial N2 fixation to NH3 at ambient conditions

Abstract

Currently, industrial-scale NH3 production almost relies on energy-intensive Haber-Bosch process from atmospheric N2 with large amount of CO2 emission, while low-cost and high-efficient catalysts are demanded for the N2 reduction reaction (NRR). In this study, Mn3O4 nanoparticles@reduced graphene oxide (Mn3O4@rGO) composite is reported as an efficient NRR electrocatalyst with excellent selectivity for NH3 formation. In 0.1 M Na2SO4 solution, such catalyst obtains a NH3 yield of 17.4 μg·h−1·mg−1cat. and a Faradaic efficiency of 3.52% at −0.85 V vs. reversible hydrogen electrode. Notably, it also shows high electrochemical stability during electrolysis process. Density functional theory (DFT) calculations also demonstrate that the (112) planes of Mn3O4 possess superior NRR activity.