Synergy of Bi O and RuO 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 NH yield and low Faradaic efficiency, especially at low overpotentials. Herein, we report the synthesis of nano-sized RuO and Bi O particles grown on functionalized exfoliated graphene (FEG) through in situ electrodeposition, denoted as RuO -Bi O /FEG. The prepared self-supporting RuO -Bi O /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 NH yield of 4.58±0.16 μg  h  cm with a high Faradaic efficiency of 14.6 % at -0.2 V versus reversible hydrogen electrode in 0.1 M Na SO electrolyte. This performance benefits from the synergistic effect between Bi O and RuO 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.