Synergy of Bi2O3 and RuO2 Nanocatalysts for Low‐Overpotential and Wide pH‐Window Electrochemical Ammonia Synthesis

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is still seriously impeded by the inferior NH3 yield and low Faradaic efficiency, especially at low overpotentials. Herein, we report the synthesis of nano-sized RuO2 and Bi2 O3 particles grown on functionalized exfoliated graphene (FEG) through in situ electrodeposition, denoted as RuO2 -Bi2 O3 /FEG. The prepared self-supporting RuO2 -Bi2 O3 /FEG hybrid with a Bi mass loading of 0.70 wt% and Ru mass loading of 0.04 wt% shows excellent NRR performance at low overpotentials in acidic, neutral and alkaline electrolytes. It achieves a large NH3 yield of 4.58±0.16 μgNH3 h-1 cm-2 with a high Faradaic efficiency of 14.6 % at -0.2 V versus reversible hydrogen electrode in 0.1 M Na2 SO4 electrolyte. This performance benefits from the synergistic effect between Bi2 O3 and RuO2 which respectively have a fairly strong interaction of Bi 6p orbitals with the N 2p band and abundant supply of *H, as well as the binder-free characteristic and the convenient electron transfer via graphene nanosheets. This work highlights a new electrocatalyst design strategy that combines transition and main-group metal elements, which may provide some inspirations for designing low-cost and high-performance NRR electrocatalysts in the future.