NH<sub>3</sub> Synthesis via Electrocatalytic N<sub>2</sub> Reduction Reaction on the Defective Surfaces of Nb<sub>2</sub>Mo<sub>2</sub>C<sub>3</sub>T<sub><i>x</i></sub> MXenes: Theoretical and Experimental Studies
Ru Feng, Hanqing Yin, Linlin Tian, Hui Zhang, Jiayi Zhang, Jingquan Liu, Aijun Du, Wenrong Yang, Zhen Liu
Abstract
Electrocatalytic N 2 reduction reaction (NRR) is a low-cost and environmental friendly strategy for NH 3 synthesis but yet needs more fundamental and applied research. Herein, we explored the NRR activity of a bimetal Nb 2 Mo 2 C 3 T x 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 N 2 molecule, and the alternating mechanism showed a downhill free energy input all through the reaction. More importantly, both surface Nb and Mo terminations of Nb 2 Mo 2 C 3 T x MXenes facilitate N 2 adsorption and demonstrate NRR activity comparable to that of the benchmark Ru. In the experiment, the Nb 2 Mo 2 C 3 T x MXene catalyst achieved an NH 3 yield of 20.77 μg h –1 mg cat –1 and a high Faraday efficiency of 31.0%, demonstrating an excellent selectivity and durability. Internal carbon layers of Nb 2 Mo 2 C 3 T x 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.