NiCo Alloy Nanoparticles Anchored on Carbon Nanotube-Decorated Carbon Nanorods as a Durable and Efficient Oxygen Electrocatalyst for Zinc-Air Flow Batteries

Abstract

The exploring of oxygen electrocatalysts with outstanding durability and efficiency toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is greatly desired for zinc-air flow batteries (ZAFBs). Herein, NiCo alloy-based nanoparticles anchored on carbon nanotube-decorated carbon nanorods (CNRs) used as a durable and efficient oxygen electrocatalyst for ZAFBs were obtained from the pyrolysis of NiCo metal−organic frameworks synthesized by a facile oil bath method. By tailoring the ratio of Ni 2+ and Co 2+ , the prepared sample, Ni 2 Co 2 -CNR, exhibits excellent ORR (E 1/2 = 0.80 V) and OER catalytic performances (a low overpotential of 310 mV at 10 mA cm −2 ). Impressively, the ZAFB assembled with a Ni 2 Co 2 -CNR catalyst shows a narrow voltage gap and remarkable operation durability with 1200 cycles at 5 mA cm −2 with every cycle of 20 min.

Selective Conversion of HMF into 3‐Hydroxymethylcyclopentylamine through a One‐Pot Cascade Process in Aqueous Phase over Bimetallic NiCo Nanoparticles as Catalyst

“…In the bimetallic NPs, the XRD peaks are located between those of Ni 0 and Co 0 . These shifts of the XRD peak positions have been attributed in several studies to the alloying effect of Ni and Co, [35–41] and in our case the shift to lower angles can be associated to a gradual replacement of Ni with Co atoms at increasing cobalt content in the NiCo@C samples. Variation of the lattice parameter of the alloy phase with the Co content follows Vegard's law [42] (linear correlation coefficient R of 0.9984) as shown in Figure S1, indicating the formation of a solid solution between Ni and Co.…”

“…In the bimetallic NPs, the XRD peaks are located between those of Ni 0 and Co 0 . These shifts of the XRD peak positions have been attributed in several studies to the alloying effect of Ni and Co, [35][36][37][38][39][40][41] and in our case the shift to lower angles can be associated to a gradual replacement of Ni with Co atoms at increasing cobalt content in the NiCo@C samples. Variation of the lattice parameter of the alloy phase with the Co content follows Vegard's law [42] (linear correlation coefficient R of The morphology, atom distribution, and particle size of monometallic and bimetallic nanoparticles prepared starting from different molar ratios of metal salt precursors were characterized by high-resolution (HR)TEM and energy-dispersive X-ray spectroscopy (EDS) elemental mapping.…”

“…X‐ray diffraction (XRD) patterns of monometallic (Co@C, Ni@C) and bimetallic (Ni 0.25 Co 0.75 @C, Ni 0.5 Co 0.5 @C, Ni 0.75 Co 0.25 @C) nanoparticles (NPs) are presented in Figure 1. Diffraction peaks at 44.5, 51.8, and 76.3° corresponding to Ni 0 (44.5), (51.8), and (76.3) (PDF 00‐004‐0850) [35] are observed in the Ni@C sample (Figure 1, green line), while in the Co@C sample, the peaks appears at 44.3, 51.5, and 75.8°, assigned to Co 0 (44.2), (51.5), and (75.8) (PDF 00‐015‐0806) (Figure 1, black line). In the bimetallic NPs, the XRD peaks are located between those of Ni 0 and Co 0 .…”

“…Similar shifts in the Co 0 BE have been attributed to the formation of NiCo alloys. [35,38] The shift in the oxide component is more complicated to assign due to the different surface oxidation degrees of the sample. Regarding to the Ni 2p 3/2 core level the component at 852.0 � 0.6 eV is ascribed to Ni 0 , and the 853.3-856 eV peaks together with satellite peaks at higher BE (858.1-863.1 eV) are characteristic of Ni 2 + .…”

Preparation and Characterization of Multi-Doped Porous Carbon Nanofibers from Carbonization in Different Atmospheres and Their Oxygen Electrocatalytic Properties Research

“…From Figure 7 , the XRD characterization was done to study the crystal composition changes in different carbonization atmospheres. For Ni x Co y -ZIFs/PAN-Ar, the XRD pattern showed the diffraction peaks of two main metallic elements at 44.5° and 51.8°, which proved that Ni x Co y alloy metal doping was realized [ 33 ]. Examining Ni x Co y -ZIFs/PAN-Air, the XRD pattern revealed diffraction peaks of multiple metal oxides at 36.8°, 44.3°,59.8°, and 65.0°, indicating Ni x Co y metal oxides doping was achieved [ 34 , 35 ].…”