NiFeMo Nanoparticles Encapsulated within Nitrogen‐Doped Reduced Graphene Oxide as Bifunctional Electrocatalysts for Zinc‐Air Batteries

Abstract

Rechargeable metal‐air batteries (MABs) have emerged as promising candidates for portable energy storage technologies because of their favorable energy/power density, safety, and cost‐effectiveness. However, the lack of advanced bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) restricts the commercial realization of rechargeable MABs. Herein, we developed a facile fabrication route to prepare N‐doped graphene oxide encapsulating nanoparticles of a ternary NiFe metal oxide (NiFeMo@N‐rGO) serving as an efficient bifunctional catalyst. The obtained NiFeMo@N‐rGO bifunctional catalyst demonstrates a comparable catalytic reactivity when compared to precious metal catalysts in alkaline electrolytes regarding ORR/OER performance (ORR: half‐wave potential of 0.82 V; OER: overpotential of 330 mV; ▵E: 0.73 V at 10 mA cm−2). The assembled zinc‐air batteries (ZABs) catalyzed by NiFeMo@N‐rGO exhibit a high power density of 120 mW cm−2 and a capacity of 721 mAh gZn−1, coupled with long‐term durability of over 200 h. This contribution paves a practical avenue to prepare efficient bifunctional catalysts for superior ZABs.

Optimal rule-of-thumb design of NiFeMo layered double hydroxide nanoflakes for highly efficient and durable overall water-splitting at large currents

“…21 A Cu-nanowire core–cell structure was used to grow NiFeMo by electrodeposition; it required 1.82 V for overall water splitting, 29 whereas NiFeMo@N-rGO exhibits a high OER overpotential of 330 mV. 30 Amorphous NiFeMo outperforms its crystalline structure for the OER catalysis, which undergoes rapid self-reconstruction. 24 Moreover, NiFeMO has not been investigated at industry-relevant current densities, which plays a key role in the industrialisation process.…”

“…Recently, NiFeMO has been widely investigated, and it has proved to be a promising candidate for industrial-relevant hydrogen production due to its excellent OER activity and scientic signicance. 21,23,24,[26][27][28][29][30][31][32][33] A careful investigation of the literature survey (Table S1, ESI †) indicated that the enhanced catalytic performance is either due to the improved quantity and quality of the active sites through compositions or the design of the nanostructures. NiFeMO is expected to be a bifunctional catalyst for overall water splitting; however, the reaction mechanism of the enhanced catalytic activity for which most active compositions is still not clearly presented.…”