One-step hydrothermal synthesis of Co–Ni–S/Ni foam as an electrocatalyst for nitrogen reduction reaction

Ammonia as a chemical substance is closely related to our daily life, and its production process has attracted researchers' attention. Due to its high energy consumption and high emission characteristics, the industrial Haber−Bosch process obviously cannot adapt to the sustainable development concept of low-carbon and environmental protection in today's society. The electrocatalytic nitrogen reduction reaction (NRR) technology is a promising method of converting unstable electrical energy into fuel for storage at ambient conditions. Here, a bimetallic catalyst, Co–Ni–S/Ni foam, is reported as an electrocatalyst to realize N₂ reduction. The in-situ growth strategy promotes the effective combination of Co₉S₈ and Ni₃S₂ on the Ni foam without any adhesive. The active centers of the bimetallic Co and Ni reasonably regulate the adsorption of various complex intermediates in the N₂ activation process, so that the Co–Ni–S/Ni foam has good N₂ activity. In 0.1 M Na₂SO₄, the designed electrocatalyst achieved an NH₃ yield of 5.05 × 10⁻¹⁰ mol s⁻¹ cm⁻² at −0.6 V vs. RHE and an optimum Faradaic efficiency of 6.23% with good electrochemical stability and selectivity. Besides, the electrocatalytic sites were also evaluated in conjunction with density functional theory.