NH3 Synthesis via Electrocatalytic N2 Reduction Reaction on the Defective Surfaces of Nb2Mo2C3Tx MXenes: Theoretical and Experimental Studies

Electrocatalytic N2 reduction reaction (NRR) is a low-cost and environmental friendly strategy for NH3 synthesis but yet needs more fundamental and applied research. Herein, we explored the NRR activity of a bimetal Nb2Mo2C3Tx MXene catalyst via both theoretical and experimental studies. Density functional theory calculations revealed that horizontal adsorption can be the most stable adsorption mode of the N2 molecule, and the alternating mechanism showed a downhill free energy input all through the reaction. More importantly, both surface Nb and Mo terminations of Nb2Mo2C3Tx MXenes facilitate N2 adsorption and demonstrate NRR activity comparable to that of the benchmark Ru. In the experiment, the Nb2Mo2C3Tx MXene catalyst achieved an NH3 yield of 20.77 μg h–1 mgcat–1 and a high Faraday efficiency of 31.0%, demonstrating an excellent selectivity and durability. Internal carbon layers of Nb2Mo2C3Tx MXenes ensured fast electron transfer and avoided self-aggregation of active sites. Structural defects also played an important role in its high NRR activity because of the formation of vast unsaturated Nb/Mo atoms.