Heteroatoms (N, F, O)-Doped CNTs on NiCo-Silica Nanocomposites for Oxygen Evolution Reaction
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RESEARCH ARTICLE-CHEMISTRY
Heteroatoms (N, F, O)-Doped CNTs on NiCo-Silica Nanocomposites for Oxygen Evolution Reaction Zulfiqar Ali1
· Mazhar Mehmood1 · Jamil Ahmad1 · Sumaira Naz2 · Yaqoob Khan3
Received: 1 April 2020 / Accepted: 13 August 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract The more electronegative atoms of element like nitrogen, fluorine and oxygen in CNTs are highly desirable for electrochemical catalytic reactions like oxygen evolution reaction (OER). Herein, we report the synthesis of in situ nitrogen-doped CNTs by CVD method on fcc NiCo alloy-silica nanocomposites in ethylene precursor containing 10% acetonitrile and their catalytic behaviour for oxygen evolution in alkaline media. The XPS analysis revealed that about 2 atomic% nitrogen was successfully doped in CNTs. Although the amount of doped nitrogen was not substantial, it played a significant role in the formation of bamboo-shaped CNTs by facilitating the conical shape of nanocatalyst. The internal core of the CNTs was analysed by TEM studies and it was found that CNTs have irregular cup and cone compartments repeated at a distance of about 50 nm. The oxygenated functional groups in the form of C=O and O–F were also found which owe their presence on the surface of CNTs to the aqueous HF treatment. The unique features like the presence of heteroatoms (N, F, O) at the graphitic planes of CNTs and its bamboo shape have collectively improved the OER performance of our synthesised carbonaceous material. As a result it exhibited OER overpotential of 315 mV at current density of 10 mA/cm2 , which was better than many reported carbonaceous materials in alkaline media. Keywords CNTs · OER · CVD · Alcogel electrolysis · NiCo-silica nanocomposites
1 Introduction Increasing clean energy demand has triggered the research activities for the production of hydrogen gas as a sustainable energy source through electrochemical water splitting [1–3]. The production of hydrogen in alkaline water electrolysers is well-established technology and it employs noble metals like iridium and platinum-based materials as electrodes for efficient water splitting process [4, 5]. Since noble metal-based electrocatalytic materials suffer from drawback of scarcity,
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Zulfiqar Ali [email protected]
1
National Centre for Nanotechnology, Department of Metallurgy and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad 45650, Pakistan
2
Materials Division, Directorate of Technology, Pakistan Institute of Nuclear Science and Technology (PINSTECH), Nilore, Islamabad 45650, Pakistan
3
Nanosciences and Catalysis Division, National Centre for Physics, Quaid-i-Azam University Campus, Islamabad, Pakistan
high price and stability issues. Therefore, development of alternatives to replace the noble metal-based electrocatalysts is desirable [6, 7]. In this regard, particularly the oxygen evolution reaction (OER) in electrochemical water splitting process requires more attention due to sluggish kin
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