An advanced electrocatalyst for efficient synthesis of ammonia based on chemically coupled NiS@MoS2 heterostructured nanospheres

Abstract

The electrochemical reduction of nitrogen, as a sustainable alternative to the known Haber–Bosch process, possesses promising application prospects in the development of renewable energy storage systems. However, the yield of NH₃ and Faraday efficiency are usually very low owing to the loss of active electrocatalysts and competitive hydrogen evolution reactions. Herein, uniform NiS@MoS₂ core–shell microspheres are controllably prepared as a potential catalyst for an ambient electrocatalytic N₂ reduction reaction. The NiS@MoS₂ microspheres possess highly active intrinsic, sufficient accessible active sites, high structural porosity, and convenient transport channels, consequently boosting the transmission of electrons and mass. Additionally, the interfacial interaction between NiS and MoS₂ facilitates electron transfer, which further improves the catalytic activity by optimizing the free energies of reaction intermediates. As a result, the titled NiS@MoS₂ shows excellent electrochemical activity and selectivity, capable of achieving a relatively high NH₃ yield of 9.66 μg h⁻¹ mg_cat⁻¹ at −0.3 V (vs. the reversible hydrogen electrode, RHE) and a high FE of 14.8% at −0.1 V vs. RHE in 0.1 M Na₂SO₄. The work demonstrated here may open a new avenue for the rational design and synthesis of catalysts for the electrochemical synthesis of ammonia.