Evidence for covalent bonding of aryl groups to MnO<sub>2</sub> nanorods from diazonium-based grafting

Bell, Kalib J.; Brooksby, Paula A.; Polson, Matthew I. J.; Downard, Alison J.

doi:10.1039/c4cc05606j

Cited by 33 publications

(32 citation statements)

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“…But the common drawback of low electronic and ionic conductivity of V 2 O 5 and MnO 2 has not improved. Downard et al 47 have modified the surface of MnO 2 nanorods with aryl groups by grafting from aryldiazonium salt solutions. They discovered that aryl groups are attached to the nanorod surface via Mn-O-C bonds however the possible involvement of Mn-C bonds cannot be discounted.…”

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A Synthesis Method of MnO₂/Activated Carbon Composite for Electrochemical Supercapacitors

Wang

Chen

2015

J. Electrochem. Soc.

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In this paper, a MnO 2 /activated carbon (AC) composite with high electrochemical performance is synthesized through a novel synthesis method (Grafting Oxidation Method). The structure and morphology are analyzed using X-ray diffraction, Fourier transmission infrared spectra, scanning electron microscopy and transmission electron microscopy. Additionally, the electrochemical properties are evaluated through cyclic voltammetry, electrochemical impedance spectra and galvanostatic cycling measurements. The results demonstrate this MnO 2 /AC composite owes homogeneous particle size of nanometer dimension. The quasi-rectangular and symmetric cyclic voltammetry curves of the composite, which are measured under a three-electrode electrochemical system with a 0.5 mol L −1 Na 2 SO 4 solution at room temperature, indicate it has an ability of rapidly reversible Faraday reaction and good electrochemical behavior. Compared to the MnO 2 /AC prepared through liquid-phase method, the composite prepared by grafting oxidation method exhibits a much higher specific capacitance which is up to 332.6 F g −1 at scanning rate of 2 mV s −1 . A laboratory capacitor assembled with this MnO 2 /AC composite electrode shows an average capacitance attenuation rate of just 0.0068% after 2000 cycles. Besides, the impedance tests results show that the charge transfer resistance of this composite is 0.92 , which is much lower than the composite (2.52 ) synthesized through liquid-phase method. Supercapacitors, also known as electrochemical capacitors or ultracapacitors, have attracted considerable interest worldwide, primarily because of their ability to provide higher power densities than batteries and higher energy densities than conventional dielectric capacitors. 1,2Because of these advantages, supercapacitors can be widely used in applications such as hybrid vehicles, electronic devices, and digital products. 3-6The most crucial factors determining the electrochemical performance rely on the electrode materials. The electrode-active materials that are widely used for supercapacitors include carbon, conducting polymers and transition-metal oxides. Considering the investigated electrode materials, transition metal oxides are considered to be good alternatives due to their high capacity from pseudocapacitance. 26 have investigated the charge storage mechanism of manganese dioxide compounds with various structures. They discovered that the capacitance of all amorphous compounds was due to faradaic processes localized at the surface and subsurface regions of the electrode. The capacitance of the crystallized materials is clearly dependent upon the crystalline structure, especially with the size of the tunnels that could be able to provide limited cations intercalation. It's also found that the interlayer spacing of the MnO 2 birnessite structure increased upon electrochemical oxidation in the presence of Na + cations in the electrolyte due to the deintercalation of Na + and the intercalation of H 2 O between the layers. 25However, a major drawba...

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A Synthesis Method of MnO₂/Activated Carbon Composite for Electrochemical Supercapacitors

Wang

Chen

2015

J. Electrochem. Soc.

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“…carbide), or both. For example, both M‐O‐C and M‐C bonds were observed on Cu, Al, and Mn oxides while only M‐O‐C bonds was detected on Cr and Fe oxides.…”

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confidence: 99%

Biocompatibility and Durability of Diazonium Adhesives on Dental Alloys

Oweis

Algizani

Mezour

et al. 2020

Journal of Prosthodontics

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Purpose A new type of diazonium‐based adhesive has been recently developed by our team to bind dental alloys (Titanium, stainless steel, and cobalt chromium) to dental polymers. Here, we explored the endurance of the resulting adhesive after thermal‐cycling and autoclave aging. Materials and Methods Polished samples of titanium (Ti), stainless steel (SS) and cobalt chromium (Co‐Cr) were coated with a diazonium‐based adhesive. Untreated samples served as controls (n = 12 per each condition). X‐ray photoelectron spectroscopy (XPS) was performed to characterize the elemental compositions of the different surfaces. Biocompatibility of the coated alloys was assessed with human gingival fibroblasts (HGF). Inductively coupled plasma (ICP) and total organic carbon (TOC) analyses were used to quantify the ions and organic matters released from the diazonium coated alloys. Endurance of the adhesives was assessed by exposing the samples to autoclaving and thermal‐cycling. The tensile strength of the poly(methylmethacrylate) (PMMA)‐alloy bond was also tested. Results Results of mechanical testing demonstrated a higher endurance of the coated CoCr, Ti, and SS compared to the uncoated alloys. The human fibroblasts cultured on the substrates remained alive and metabolically active, and the coatings did not release significant amounts of toxic chemicals in solutions. Conclusions The results further support the use of diazonium‐based adhesives as new coupling agents for dental applications.

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“…We thus focused on the O 1s peak as metal‐O‐carbon bonds are expected to be present at ca. 533 eV ,. Our analysis evidences first that the relative amount of oxygen atoms detected at the surface (i. e., the O/In ratio, Table S2) increases upon electrochemical grafting, despite the fact that the grafted porphyrin is free of oxygen atoms.…”

Section: Figurementioning

confidence: 99%

Introducing Molecular Functionalities within High Surface Area Nanostructured ITO Electrodes through Diazonium Electrografting

et al. 2018

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Efficient and homogeneous functionalization of 3D nanostructured transparent ITO electrodes was reproducibly achieved by electrochemical reduction of in‐situ generated free‐base porphyrin diazonium salts. The resulting modified electrodes were characterized by cyclic voltammetry and voltabsorptometry, UV‐visible absorption, resonance Raman and XPS. The overall results strongly support the formation of covalently linked electroactive porphyrin oligomers on the ITO surface, that are highly stable towards desorption or hydrolysis in organic as well as mild hydrolytic conditions. Further metalation by zinc ions was quantitatively achieved, thus opening new opportunities for the preparation of robust high‐surface area photoelectrodes with adjustable properties.

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Evidence for covalent bonding of aryl groups to MnO₂ nanorods from diazonium-based grafting

Abstract: We show here that the surface of MnO2 nanorods can be modified with aryl groups by grafting from aqueous and non-aqueous solutions of aryldiazonium salts. X-ray photoelectron spectroscopy provides direct evidence for covalent bonding of aryl groups to MnO2 through surface oxygens.

Cited by 33 publications

References 35 publications

A Synthesis Method of MnO₂/Activated Carbon Composite for Electrochemical Supercapacitors

A Synthesis Method of MnO₂/Activated Carbon Composite for Electrochemical Supercapacitors

Biocompatibility and Durability of Diazonium Adhesives on Dental Alloys

Introducing Molecular Functionalities within High Surface Area Nanostructured ITO Electrodes through Diazonium Electrografting

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Evidence for covalent bonding of aryl groups to MnO2 nanorods from diazonium-based grafting

Abstract: We show here that the surface of MnO2 nanorods can be modified with aryl groups by grafting from aqueous and non-aqueous solutions of aryldiazonium salts. X-ray photoelectron spectroscopy provides direct evidence for covalent bonding of aryl groups to MnO2 through surface oxygens.

Cited by 33 publications

References 35 publications

A Synthesis Method of MnO2/Activated Carbon Composite for Electrochemical Supercapacitors

A Synthesis Method of MnO2/Activated Carbon Composite for Electrochemical Supercapacitors

Biocompatibility and Durability of Diazonium Adhesives on Dental Alloys

Introducing Molecular Functionalities within High Surface Area Nanostructured ITO Electrodes through Diazonium Electrografting

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Evidence for covalent bonding of aryl groups to MnO₂ nanorods from diazonium-based grafting

A Synthesis Method of MnO₂/Activated Carbon Composite for Electrochemical Supercapacitors

A Synthesis Method of MnO₂/Activated Carbon Composite for Electrochemical Supercapacitors