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

Abstract

Electrochemical ammonia synthesis (EAS) is considered to be an ecofriendly and sustainable method for artificial N2 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 μg 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 N2 molecules, as reflected by its greater adsorption energy (−0.32 eV vs. − 0.10 eV), greater N≡N bond distance (1.223 Å vs. 1.159 Å), lower energy barrier (0.40 eV vs. 0.78 eV), and greater charge transfer from active sites to N2 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.