Fabricating freestanding electrocatalyst with bismuth-iron dual active sites for efficient ammonia synthesis in neutral media

Abstract

Electrocatalytic N₂ reduction (NRR) has been regarded as a promising approach for environment-friendly and sustainable ammonia (NH₃) synthesis. However, developing cost-effective electrocatalysts with high NRR efficiency at low overpotential in neutral media remains a great challenge. In this paper, a freestanding NRR electrocatalyst, BiFeO/FCC, has been developed by in situ growth of bismuth ferrite (Bi₂₅FeO₄₀) on functionalized carbon cloth (FCC), which exhibits high NRR activity with a maximum NH₃ yield of 3.88 μg h⁻¹ cm⁻² (at −0.40 V vs. reversible hydrogen electrode [RHE]) and a Faradaic efficiency of 12.71% (at −0.45 V vs. RHE) in 0.1 M Na₂SO₄. The synergistic effect of the abundant exposed bismuth and iron dual active sites confined in the lattice, the binder-free nature of the electrode and the excellent conductivity of the carbon substrate enable the easy adsorption/activation of N₂ and accelerate the electron transfer simultaneously, thus boosting its NRR performance. This work is significant to design low-cost, and high-efficient NRR catalysts for large-scale electrocatalytic NH₃ synthesis.