^“In‐Situ Grown Nickel‐Cobalt (NiCo) Alloy Nanoparticles Decorated on Petal‐Like Nitrogen‐Doped Carbon Spheres for Efficient OER Activity^”**

Abstract

Herein, we report in-situ NiCo alloy nanoparticle formation of extremely small diameter (1-5 nm) on nitrogen (N)-doped carbon spheres by the CVD method at 750 °C temperature, followed by its use in oxygen evolution reaction (OER) electrocatalysis. Secondary electron microscope (SEM) imaging shows the open as well as close cup-shaped spheres and discs, while transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies confirmed the ultrafine NiCo alloy particles' formation on nitrogen-doped multilayer graphitized carbon. Moreover, Raman spectroscopy revealed the I D /I G ratio to be about 1.57 for N-doped graphitic multilayer carbon, thereby suggesting the defective nature of graphitized carbon material, which may possibly be due to the incorporation of nitrogen atoms into graphitic carbon layers. The formation of extremely small NiCo alloy nanoparticles is attributed to the reducing carbonaceous environment of CVD constituted by ethanol and acetonitrile precursors, while carbon spheres/disks seem to be catalysed by silica substrate originated from an alcogel catalyst. In addition, synthesised hybrid nanocomposites materials were tested for OER electrocatalysis in alkaline conditions and it was found that synthesized NiCo alloy nanoparticles decorated on N-doped carbon spheres have an overpotential 310 mV at current density of 10 mA/cm 2 which is just 5 mV higher than that of benchmark Ir/C (20 wt % Ir) electrocatalyst. The multiphase components of synthesised material like; electrically conductive carbon, nitrogen-doped sites and well-separated ultrafine NiCo alloy nanoparticles synergistically contributed towards better OER activity in alkaline conditions.

NiCo alloy‐anchored self‐supporting carbon foam as a bifunctional oxygen electrode for rechargeable and flexible Zn–air batteries

“…The peaks at 777.8, 779.5, 782.6, and 786.2 eV correspond to metal elemental Co, Co 3+ , high-spin Co 2+ ion vibration peaks, and satellite peaks, respectively, in which the metallic Co species occupies dominates the Co 2p spectrum. 20,24 The above results echo the crystal structure characterizations, further confirming the formation of NiCo alloy structure. Figure 2E shows the high-resolution C ls XPS spectra of NiCo@SCF, which can be fitted into five peaks.…”

Heterostructure NiCo-Alloy Nanosheet Embedded Ceria Nanorods: A Highly Efficient Bifunctional Electrocatalyst toward Oxygen Evolution Reaction and Oxygen Reduction Reaction

“…They revealed a significant enhancement of catalytic efficiency for OER with η = 310 mV at 10 mA cm −2 . 24 In another study, Ding et al investigated the OER performance of bimetallic FeNi 3 alloy nanoparticles. 25 The resulting FeNi 3 alloy nanoparticles derived from the metal−organic framework (MOF) demonstrated excellent performance (η= 269 mV at 10 mA cm −2 ) with accelerated kinetics (Tafel slope ∼72 mV dec −1 ).…”

“…Recently, heterogeneous transition metal alloy based electrode materials have been explored for the ORR and OER because of their high catalytic performance and corrosion resistance in alkaline conditions. , For instance, Ali et al synthesized NiCo alloy nanoparticles decorated over nitrogen-doped carbon spheres. They revealed a significant enhancement of catalytic efficiency for OER with η = 310 mV at 10 mA cm –2 . In another study, Ding et al investigated the OER performance of bimetallic FeNi 3 alloy nanoparticles .…”

In‐situ Electrochemical Activation Enhances the OER Catalytic Performance of Ag NWs@ZIF‐67 in Alkaline Simulated Seawater

“…[9] Based on extensive research, compounds of transition metal elements such as Fe, Co, Ni, Mn, Cu and others, which are rich in the earth's crust, have been effectively developed in the field of electrolysis of water, and the catalytic activity of some of these compounds has even reached the standard of precious metal-based catalysts. [10] As one of the transition metal elements with multiple valencies, Co (Co II /Co III ) has long been of interest in theoretical practice due to the redox potential between valence states is closer to the theoretical decomposition potential of electrolysis of water (E = 1.23 V vs. RHE), and the element is abundant. [11,12] Metal organic frameworks (MOFs) have attracted extensive attention in the field of electrocatalysis due to their high specific surface area, abundant pore structure, and high design flexibility.…”

“…(2) Depositing a chloride impermeable cover layer on the surface of the electrode material to increase the OER catalytic selective activity of the material [9] . Based on extensive research, compounds of transition metal elements such as Fe, Co, Ni, Mn, Cu and others, which are rich in the earth‘s crust, have been effectively developed in the field of electrolysis of water, and the catalytic activity of some of these compounds has even reached the standard of precious metal‐based catalysts [10] . As one of the transition metal elements with multiple valencies, Co (Co II /Co III ) has long been of interest in theoretical practice due to the redox potential between valence states is closer to the theoretical decomposition potential of electrolysis of water (E=1.23 V vs. RHE), and the element is abundant [11,12] …”