Effect of Power Density on the Electrochemical Properties of Undoped Amorphous Carbon (a-C) Thin Films

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@article{ff1de65de8cc4a149a104ea0572dc36e,
title = "Effect of Power Density on the Electrochemical Properties of Undoped Amorphous Carbon (a-C) Thin Films",
abstract = "Undoped a-C thin films were deposited with varying power density from 10 to 25 W/cm2 using unbalanced closed-field magnetron sputtering (CFUBMS). The effect of power density on the physical and electrochemical properties was investigated by experimental characterization methods and atomistic simulations. XPS indicated that the films were composed mostly of sp2-bonded carbon (55–58 at.{\%}) with a small amount of oxygen (8–9 at.{\%}) in the surface region. The films appeared completely amorphous in XRD. The ID/IG ratio obtained by Raman spectroscopy indicated an increase from 1.76 to 2.34 with power density. The experimental and simulated data suggested a possible ordering and/or clustering of the sp2 phase with power density as the cause of the improved electrical properties of the a-C films. The electrochemical properties of a-C were between those of glassy carbon and tetrahedral amorphous carbon with potential windows ranging from 2.77 to 2.93 V and double-layer capacitance values around 0.90 μF cm−2. Electron transfer for Ru(NH3)6 3+/2+ and FcMeOH+1/0 was reversible whereas that for IrCl6 2−/3− was quasi-reversible. Peak potential separation of dopamine and oxidation potential of ascorbic acid decreased with power density, correlating with the structural and electrical changes of the films. The a-C thin films deposited by CFUBMS are inherently conductive and their physical properties can be adjusted by varying the deposition parameters to a wide range of electrochemical applications.",
keywords = "amorphous carbon, ascorbic acid, closed-field unbalanced magnetron sputtering, dopamine, electrochemical properties, CATALYSIS, HETEROGENEOUS ELECTRON-TRANSFER, PERFORMANCE, ELECTROANALYSIS, NITRIDE, BORON-DOPED DIAMOND, KINETICS, GROWTH, DOPAMINE, SURFACES",
author = "Tommi Palom{\"a}ki and Caro, {Miguel A.} and Niklas Wester and Sami Sainio and Jarkko Etula and Johansson, {Leena Sisko} and Han, {Jeon G.} and Jari Koskinen and Tomi Laurila",
year = "2019",
month = "4",
day = "1",
doi = "10.1002/elan.201800738",
language = "English",
volume = "31",
pages = "746--755",
journal = "ELECTROANALYSIS",
issn = "1040-0397",
number = "4",

}

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TY - JOUR

T1 - Effect of Power Density on the Electrochemical Properties of Undoped Amorphous Carbon (a-C) Thin Films

AU - Palomäki, Tommi

AU - Caro, Miguel A.

AU - Wester, Niklas

AU - Sainio, Sami

AU - Etula, Jarkko

AU - Johansson, Leena Sisko

AU - Han, Jeon G.

AU - Koskinen, Jari

AU - Laurila, Tomi

PY - 2019/4/1

Y1 - 2019/4/1

N2 - Undoped a-C thin films were deposited with varying power density from 10 to 25 W/cm2 using unbalanced closed-field magnetron sputtering (CFUBMS). The effect of power density on the physical and electrochemical properties was investigated by experimental characterization methods and atomistic simulations. XPS indicated that the films were composed mostly of sp2-bonded carbon (55–58 at.%) with a small amount of oxygen (8–9 at.%) in the surface region. The films appeared completely amorphous in XRD. The ID/IG ratio obtained by Raman spectroscopy indicated an increase from 1.76 to 2.34 with power density. The experimental and simulated data suggested a possible ordering and/or clustering of the sp2 phase with power density as the cause of the improved electrical properties of the a-C films. The electrochemical properties of a-C were between those of glassy carbon and tetrahedral amorphous carbon with potential windows ranging from 2.77 to 2.93 V and double-layer capacitance values around 0.90 μF cm−2. Electron transfer for Ru(NH3)6 3+/2+ and FcMeOH+1/0 was reversible whereas that for IrCl6 2−/3− was quasi-reversible. Peak potential separation of dopamine and oxidation potential of ascorbic acid decreased with power density, correlating with the structural and electrical changes of the films. The a-C thin films deposited by CFUBMS are inherently conductive and their physical properties can be adjusted by varying the deposition parameters to a wide range of electrochemical applications.

AB - Undoped a-C thin films were deposited with varying power density from 10 to 25 W/cm2 using unbalanced closed-field magnetron sputtering (CFUBMS). The effect of power density on the physical and electrochemical properties was investigated by experimental characterization methods and atomistic simulations. XPS indicated that the films were composed mostly of sp2-bonded carbon (55–58 at.%) with a small amount of oxygen (8–9 at.%) in the surface region. The films appeared completely amorphous in XRD. The ID/IG ratio obtained by Raman spectroscopy indicated an increase from 1.76 to 2.34 with power density. The experimental and simulated data suggested a possible ordering and/or clustering of the sp2 phase with power density as the cause of the improved electrical properties of the a-C films. The electrochemical properties of a-C were between those of glassy carbon and tetrahedral amorphous carbon with potential windows ranging from 2.77 to 2.93 V and double-layer capacitance values around 0.90 μF cm−2. Electron transfer for Ru(NH3)6 3+/2+ and FcMeOH+1/0 was reversible whereas that for IrCl6 2−/3− was quasi-reversible. Peak potential separation of dopamine and oxidation potential of ascorbic acid decreased with power density, correlating with the structural and electrical changes of the films. The a-C thin films deposited by CFUBMS are inherently conductive and their physical properties can be adjusted by varying the deposition parameters to a wide range of electrochemical applications.

KW - amorphous carbon

KW - ascorbic acid

KW - closed-field unbalanced magnetron sputtering

KW - dopamine

KW - electrochemical properties

KW - CATALYSIS

KW - HETEROGENEOUS ELECTRON-TRANSFER

KW - PERFORMANCE

KW - ELECTROANALYSIS

KW - NITRIDE

KW - BORON-DOPED DIAMOND

KW - KINETICS

KW - GROWTH

KW - DOPAMINE

KW - SURFACES

UR - http://www.scopus.com/inward/record.url?scp=85060661833&partnerID=8YFLogxK

U2 - 10.1002/elan.201800738

DO - 10.1002/elan.201800738

M3 - Article

VL - 31

SP - 746

EP - 755

JO - ELECTROANALYSIS

JF - ELECTROANALYSIS

SN - 1040-0397

IS - 4

ER -

ID: 31972277