MOF-derived Fe2O3@MoS2: An efficient electrocatalyst for ammonia synthesis under mild conditions

Electrochemical ammonia synthesis (EAS) is considered to be an ecofriendly and sustainable method for artificial N-2 fixation. It is urgent to develop cost-effective and efficient electrocatalysts for EAS because present catalysts have low activity and poor selectivity. Herein, Fe2O3 nanoparticles anchored on MoS2 nanoflowers (Fe2O3@-MoS2) were developed as a highly efficient EAS electrocatalyst under ambient conditions. Electrochemical measurements indicate that Fe2O3@MoS2 achieves a remarkable NH3 yield of 112.15 mu g h(-1) mgcat(-1) at -0.6 V vs. reversible hydrogen electrode (RHE) and a high faradaic efficiency (FE) of 8.62% at -0.4 V vs. RHE in 0.1 M Na2SO4, much better than the EAS performance of separate MoS2 and Fe2O3. The superior electrochemical stability is confirmed by long-term (at least 24 h) continuous tests. Density functional theory (DFT) calculations show that Fe2O3@MoS2, compared to MoS2, is better able to activate inert N-2 molecules, as reflected by its greater adsorption energy (-0.32 eV vs. -0.10 eV), greater N equivalent to N bond distance (1.223 angstrom vs. 1.159 angstrom), lower energy barrier (0.40 eV vs. 0.78 eV), and greater charge transfer from active sites to N-2 molecules (1.16 e(-) vs. 0.62 e(-)). Thus, this work provides new perspectives on the development of efficient EAS catalysts using MoS2-based materials as the substrate.

Automated summary

This study presents a highly efficient electrocatalyst Fe2O3@-MoS2 for electrochemical ammonia synthesis (EAS) at ambient conditions. The Fe2O3@-MoS2 catalyst demonstrates remarkable ammonia yield and high faradaic efficiency, along with superior electrochemical stability. Density functional theory (DFT) calculations reveal that Fe2O3@-MoS2 is capable of activating inert N-2 molecules more effectively than MoS2.