High-performance bifunctional oxygen electrocatalysts for zinc-air batteries over nitrogen-doped carbon encapsulating CoNi nanoparticles

Abstract

The nitrogen doped carbon (NC) encapsulating metal particles (metal/NC) are promising low-cost bifunctional oxygen electrocatalysts for rechargeable Zn-air batteries. However, the states of the art catalytic performance are still significantly restricted by the limited content of active sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a series of NC encapsulating CoNi samples as a bifunctional catalyst for both ORR and OER were synthesized via a simple pyrolysis method. Large surface area and high content M-Nx active sites promote the ORR activity and accelerate the surface reconstruction layer for high OER performance. The NC encapsulating CoNi with optimized Co/Ni ratio (2 : 1) shows high ORR activity with a half-wave of potential (0.85 V) and a low overpotential of 309 mV for OER. Rechargeable Zn-air battery assembled by an air cathode with the NC encapsulating CoNi exhibits a power density of 143 mW cm−2 and good cyclability over 100 h at 10 mA cm-2. This mechanism work provides a feasible strategy for developing high activity and low cost bifunctional oxygen electrocatalysts.

Facile synthesis of MnO/NC nanohybrids toward high-efficiency ORR for zinc–air battery

“…The carbon support plays a crucial role in preventing MnO nanoparticles agglomeration, which is conducive to maintaining the high ORR stability for the MnO/NC nanohybrids. 31 The composition and bonding characteristics of all samples were further elucidated using XPS. In the wide XPS spectra (Fig.…”

“…The carbon support plays a crucial role in preventing MnO nanoparticles agglomeration, which is conducive to maintaining the high ORR stability for the MnO/NC nanohybrids. 31 …”

Facile Composition of CoNi and Graphene as a Free-Standing Cathode for a High-Performance Solid-State Zinc–Air Battery

“…Additionally, graphene can enhance the active sites and stability of the composites due to its accelerated ion diffusion property, and it is also easily regulated by nitrogen sources [11]. As two typical graphene materials, graphene oxide and reduced graphene oxide have different properties such as electrocatalyst adhesion, conductivity, porous structure, etc., because of the different oxygen levels and binding configurations [12][13][14]. Then, the optimized oxygen functional groups on the graphene surface are beneficial for film formation, and they can also reduce the conductivity to a certain extent and promote the formation of specific pore structures.…”

“…Recently, bimetallic alloys such as CoNi have emerged as a promising option for promoting the formation of a reconstruction layer, which can accelerate the ORR process. Compared to their single-element counterparts, these bimetallic alloys exhibit enhanced activity and stability [12,[15][16][17]. Here, we developed a free-standing CoNi/graphene composite cathode without current collectors and binders.…”