Heterostructure design on honeycomb borophene/Mo2C: A novel strategy for nitrogen fixation

Abstract

In terms of its ecological and sustainable nature, electrochemical nitrogen reduction reaction (e-NRR) is widely recognized as the ideal solution to replace conventional ammonia production techniques. Unfortunately, poor Faraday efficiency (FE) with lower e-NRR selectivity limits its large-scale application. Previous studies have identified Mo2C as an optimistic electrocatalyst for e-NRR, exhibiting great ammonia yield. However, Mo2C suffers from Mo leaching during the electrochemical reaction process, thus reducing the stability of the catalyst. Herein, we propose a new electrocatalyst based on first-principles calculations: HB/α-Mo2C. This heterostructure is composed of Mo2C covered with a layer of Honeycomb Borophene (HB). The HB layer serves two purposes: to ensure the stability of the catalyst and improve the FE of the reaction. Our findings demonstrate the HB/α-Mo2C performs the highest catalytic activity via a mixed mechanism with a limiting potential as low as -0.16 V, which was determined to be caused by the transfer of electrons from the active sites of the boron atoms to the adsorbate. Furthermore, the limiting potential of HER, a competing reaction, was found to be as high as −0.56 V, confirming the high efficiency of HB/α-Mo2C towards e-NRR. This present work contributes to the development of new strategies for e-NRR catalyst design.