Self-templating hydrothermal synthesis of carbon-confined double-shelled Ni/NiO hollow microspheres for diphenylamine detection in fruit samples

Bifunctional electrocatalysts for water splitting from a bimetallic (V doped-NixFey) Metal–Organic framework MOF@Graphene oxide composite

The lack of well-performing, atom-economic, earth-abundant, transition metal electrocatalysts for the oxygen evolution reaction (OER) in water electrolysers and rechargeable metal–air batteries remains an impediment for their ubiquitous application. Accordingly, nickel oxide has attracted attention as a potential OER catalyst, but its inferior catalytic activity due to the non-participation of its concealed active sites is challenging. Herein, a reported nitrogen-doped graphitic carbon shell-embedded nickel nanoparticle electrocatalyst (Ni-D-700) was investigated to enhance its oxygen evolution activity via the surface dissolution method. This method, which is widely used for dealloying bimetallic nanoparticles to improve their activity, was employed to study the effect of leaching and its duration on a monometallic nanoparticle catalyst. The resultant oxide layer formed on the surface of the nickel nanoparticles (Ni0@Ni2+/Ni3+) exhibited outstanding oxygen evolution activity (1.52 V onset potential vs. RHE, 53.4 mV dec−1 Tafel slope and 360 mV overpotential at 10 mA cm−2 current density) and mass activity, much higher than that of the precursor catalyst. This is attributed to the participation of maximum metal/metal oxide interfaces generated in the process of leaching, which otherwise tend to remain subdued, leading to insufficient catalytic activity.

Enhancing the oxygen evolution activity of nitrogen-doped graphitic carbon shell-embedded nickel/nickel oxide nanoparticles by surface dissolution

Fe doped NiO incorporated porous carbon hybrid electrocatalyst: A state of the art analysis for the selective sensing of acetaminophen in biological and pharmaceutical samples

In this work, mesoporous nickel oxide (NiO) hierarchical nanostructures were synthesized by a facile approach by hydrothermal reaction and subsequent calcination. The phase structure, microstructure, element composition, surface area, and pore size distribution of the as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and the Brunauer–Emmett–Teller (BET) technique. The precursor of Ni3(NO3)2(OH)4 nanosheet, Ni3(NO3)2(OH)4 microsphere, and Ni(HCO3)2 sub-microsphere was obtained by hydrothermal reaction at 160 °C for 4 h when the ratio of Ni2+/HMT (hexamethylenetetramine) was 2:1, 1:2, and 1:3, respectively. After calcination at 400 °C for 2 h, the precursors were completely transformed to mesoporous NiO hierarchical nanosheet, microsphere, and sub-microsphere. When evaluated as additives of the thermal decomposition of ammonium perchlorate (AP), these NiO nanostructures significantly reduce the decomposition temperature of AP, showing obvious catalytic activity. In particular, NiO sub-microsphere have the best catalytic role, which can reduce the high temperature decomposition (HTD) and low temperature decomposition (LTD) temperature by 75.2 and 19.1 °C, respectively. The synthetic approach can easily control the morphology and pore structure of the NiO nanostructures by adjusting the ratio of Ni2+/HMT in the reactants and subsequent calcination, which avoids using expensive templates or surfactant and could be intended to prepare other transition metal oxide.

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HMT-Controlled Synthesis of Mesoporous NiO Hierarchical Nanostructures and Their Catalytic Role towards the Thermal Decomposition of Ammonium Perchlorate

Xiangfeng Guan

Papers

HMT-Controlled Synthesis of Mesoporous NiO Hierarchical Nanostructures and Their Catalytic Role towards the Thermal Decomposition of Ammonium Perchlorate