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.