Revealing the Origin of Nitrogen Electroreduction Activity of Molybdenum Disulfide Supported Iron Atoms

Despite encouraging progress in electrocatalytic nitrogen reduction reaction (NRR) catalyst development, efficient NRR has proven extremely challenging to achieve in practice, underscoring the fact that N 2 is a highly stable, non-polar molecule. Hence, discovering electrocatalysts with considerable yields for NRR is highly desired. In this work, combining the state-of-the-art ab initio molecular dynamics and the computational standard hydrogen electrode method, we studied the thermodynamics and kinetics of NRR on Fe x @MoS 2 ( x = 1–3) electrocatalysts under an applied electrochemical environment. NH 2 –NH 2 was determined to be an important intermediate, and its N–N bond breaking was proposed as the rate-determining step. On Fe 1 @MoS 2, we demonstrated that the NRR activity of Fe 1 @MoS 2 can be attributed to the electric field effect, which triggers the dynamical orientation of NH 2 –NH 2 from side-on adsorption mode to end-on one. The induced interaction between the dipole moment of the titled N–N bond with the local electric field facilitates the N–N bond cleavage. On the contrary, such an electric field effect on Fe 2 @MoS 2 and Fe 3 @MoS 2 is minor. Two Fe sites synergistically interacting with NH 2 –NH 2 leads to more efficient N–N bond activation than Fe 1 @MoS 2 . This work not only illuminates the NRR activity origin of single, double, and triple Fe sites supported by MoS 2 but also proposes two valuable strategies from the perspective of kinetics to accelerate the catalysis of NRR: one is by the electric field effect, the other is to use the synergistic effect.