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

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is still seriously impeded by the inferior NH 3 yield and low Faradaic efficiency, especially at low overpotentials. Herein, we report the synthesis of nanosized RuO 2 and Bi 2 O 3 particles grown on functionalized exfoliated graphene (FEG) through in situ electrodeposition, denoted as RuO 2 À Bi 2 O 3 /FEG. The prepared self-supporting RuO 2 À Bi 2 O 3 /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 3 yield of 4.58 � 0.16 μg NH3 h À 1 cm À 2 with a high Faradaic efficiency of 14.6 % at À 0.2 V versus reversible hydrogen electrode in 0.1 M Na 2 SO 4 electrolyte. This performance benefits from the synergistic effect between Bi 2 O 3 and RuO 2 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 maingroup metal elements, which may provide some inspirations for designing low-cost and high-performance NRR electrocatalysts in the future.

Nanoengineering Metal–Organic Frameworks and Derivatives for Electrosynthesis of Ammonia

“…With our continuous interest in the electrochemical synthesis of NH 3 [ 33 – 37 ], this review presents a systematic discussion of the MOFs and MOF-derived materials that are being studied for the electrosynthesis of ammonia from N 2 and NO 3 − . First, the fundamental principles of the electrosynthesis of NH 3 are illustrated.…”

Architecting Bismuth Molybdate Nanoparticles with Abundant Oxygen Vacancies and High Bismuth Concentration for Efficient N2 Electroreduction to NH3

“…Catalysts made of earth‐abundant elements display great potential as substitutes for noble‐metal‐based catalysts (e.g., Au, [ 8,9 ] Pd, [ 10 ] Ru, [ 11,12 ] and Rh [ 13 ] ) in practical applications due to their low cost and abundant reserves. Up to now, numerous cost‐efficient noble‐metal free NRR electrocatalysts have been developed, such as transition‐metal‐based catalysts (e.g., MoS 2 Qds, [ 14 ] defect‐rich MoS 2 nanoflowers, [ 15 ] MnO, [ 16 ] few‐layer antimonene, [ 17 ] and Fe 2 O 3 ‐CNT [ 18 ] ), main group metal‐based catalysts (e.g., bismuth nanoparticles, [ 19 ] SnO 2 , [ 20,21 ] Bi 2 O 3 /RuO 2 , [ 22 ] fluorine‐doped SnO 2 , [ 23 ] SnS 2 , [ 24,25 ] Bi 2 O 3 /FEG, [ 26 ] Bi 4 V 2 O 11 /CeO 2 , [ 27 ] and BiOCl/MXene [ 28 ] ) and metal‐free materials (boron‐doped graphene, [ 29 ] N‐doped porous carbon, [ 30 ] and Li + incorporated PEBCD [ 31 ] ). Despite encouraging progress in electrocatalytic NRR, three major bottlenecks seriously impede its practical applications.…”