Impurity tuning for enhanced electrocatalytic reduction of N2 to NH3 over Fe/Co Co-doped MoS2 nanosheets

The electrochemical N2 reduction reaction (NRR) has attracted much attention for its use in the production of fertilizers and other chemicals. Herein, we demonstrate that the NRR can be enhanced when using Fe/Co co-doped MoS2 (FeCo–MoS2) nanosheets as the electrocatalyst. At the optimal doping concentration, the FeCo–MoS2 nanosheets provided a NH3 yield rate of 3.27 μg/h/cm2 at −0.55 V [vs reversible hydrogen electrode (RHE)], a value superior to those of undoped MoS2, Fe-doped MoS2, and Co-doped MoS2 samples by 191, 176, and 116%, respectively. Moreover, the Faradaic efficiency of 6.28% at −0.35 V (vs RHE) exceeded those of the undoped MoS2, Fe-doped MoS2, and Co-doped MoS2 samples by 217, 186, and 132%, respectively. Density functional theory calculations revealed that the preferred reaction mediated by the FeCo–MoS2 electrocatalyst followed a distal pathway, with its potential-determining step having an energy barrier (0.54 eV) lower than that of undoped MoS2 (1.13 eV), suggesting that the FeCo–MoS2 nanosheets possessed superior electrocatalytic activity. We conclude that Fe and Co are efficient dopants for boosting the NRR activity of MoS2 catalysts.