University of Oulu

Chem. Mater. 2021, 33, 17, 6813–6824

What determines the electrochemical properties of nitrogenated amorphous carbon thin films?

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Author: Etula, Jarkko1; Wester, Niklas1; Liljeström, Touko1;
Organizations: 1Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
2Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
3Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, 90570 Oulu, Finland
4Department of Physics, University of Jyväskylä, 40500 Jyväskylä, Finland
5Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, 02150 Espoo, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe2021110453733
Language: English
Published: American Chemical Society, 2021
Publish Date: 2021-11-04
Description:

Abstract

Linking structural and compositional features with the observed electrochemical performance is often ambiguous and sensitive to known and unknown impurities. Here an extensive experimental investigation augmented by computational analyses is linked to the electrochemical characterization of in situ nitrogen-doped tetrahedral amorphous carbon thin films (ta-C:N). Raman spectroscopy combined with X-ray reflectivity shows nitrogen disrupting the sp3 C–C structure of the reference ta-C, supported by the observations of graphitic nitrogen substitution in X-ray absorption spectroscopy. The surface roughness also increases, as observed in atomic force microscopy and atomic-level computational analyses. These changes are linked to significant increases in the hydrogen and oxygen content of the films by utilizing time-of-flight elastic recoil detection analysis. The conductivity of the films increases as a function of the nitrogen content, which is seen as a facile reversible outer-sphere redox reaction on ta-C:N electrodes. However, for the surface-sensitive inner-sphere redox (ISR) analytes, it is shown that the electrochemical response instead follows the oxygen and hydrogen content. We argue that the passivation of the required surface adsorption sites by hydrogen decreases the rates of all of the chemically different ISR probes investigated on nitrogenated surfaces significantly below that of the nitrogen-free reference sample. This hypothesis can be used to readily rationalize many of the contradictory electrochemical results reported in the literature.

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Series: Chemistry of materials
ISSN: 0897-4756
ISSN-E: 1520-5002
ISSN-L: 0897-4756
Volume: 33
Issue: 17
Pages: 6813 - 6824
DOI: 10.1021/acs.chemmater.1c01519
OADOI: https://oadoi.org/10.1021/acs.chemmater.1c01519
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Subjects:
Funding: We acknowledge the provision of facilities by RawMatters Finland Infrastructure (RAMI, no. 292884), Aalto University Bioeconomy, and OtaNano - Nanomicroscopy Center (Aalto- NMC). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract no. DE-AC02- 76SF00515. We acknowledge CSC − IT Center for Science, Finland, for computational resources. S.S. acknowledges funding from the Walter Ahlström Foundation. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 841621 and the Business Finland FEPOD 2117731 project. M.A.C. acknowledges funding from the Academy of Finland under project number 30488.
EU Grant Number: (841621) TACOMA - Towards Application specific tailoring of CarbOn nanoMAterials
Copyright information: © 2021 The Authors. Published by American Chemical Society. Published under the CC-BY license.
  https://creativecommons.org/licenses/by/4.0/