Fe Foam-Supported FeS<sub>2</sub>–MoS<sub>2</sub> Electrocatalyst for N<sub>2</sub> Reduction under Ambient Conditions
Mengle Yang, Zhongxin Jin, Chenglong Wang, Xixian Cao, Xinming Wang, Huiyuan Ma, Haijun Pang, Lichao Tan, Guixin Yang
Abstract
Highly efficient catalysts with enough selectivity and stability are essential for electrochemical nitrogen reduction reaction (e-NRR) that has been considered as a green and sustainable route for synthesis of NH3. In this work, a series of three-dimensional (3D) porous iron foam (abbreviated as IF) self-supported FeS2–MoS2 bimetallic hybrid materials, denoted as FeS2–MoS2@IFx, x = 100, 200, 300, and 400, were designed and synthesized and then directly used as the electrode for the NRR. Interestingly, the IF serving as a slow-releasing iron source together with polyoxomolybdates (NH4)6Mo7O24·4H2O as a Mo source were sulfurized in the presence of thiourea to form self-supported FeS2–MoS2 on IF (abbreviated as FeS2–MoS2@IF200) as an efficient electrocatalyst. Further material characterizations of FeS2–MoS2@IF200 show that flower cluster-like FeS2–MoS2 grows on the 3D skeleton of IF, consisting of interconnected and staggered nanosheets with mesoporous structures. The unique 3D porous structure of FeS2–MoS2@IF together with synergy and interface interactions of bimetallic sulfides would make FeS2–MoS2@IF possess favorable electron transfer tunnels and expose abundant intrinsic active sites in the e-NRR. It is confirmed that synthesized FeS2–MoS2@IF200 shows a remarkable NH3 production rate of 7.1 ×10–10 mol s–1 cm–2 at −0.5 V versus the reversible hydrogen electrode (vs RHE) and an optimal faradaic efficiency of 4.6% at −0.3 V (vs RHE) with outstanding electrochemical and structural stability.