Unravelling microstructure-electroactivity relationships in free-standing polycrystalline boron-doped diamond: A mapping study

Zhichao Liu, Simona Baluchová, Ziyu Li, Yaiza Gonzalez-Garcia, Clive E. Hall, Josephus G. Buijnsters*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)
37 Downloads (Pure)

Abstract

In this work, four different techniques were concurrently applied to study the interplay between local electroactivity and electrode surface characteristics of free-standing, polycrystalline boron-doped diamond (BDD). Scanning electron microscopy, electron back-scatter diffraction, Raman mapping and scanning electrochemical microscopy were used to probe the electrode morphology, grain orientation and boundaries, composition, and local electrochemical activity, respectively. Both nucleation and growth BDD surfaces together with the cross-section area were carefully investigated for the first time in a single study using the combination of all four techniques. This enabled us to obtain significant insights into the highly heterogeneous nature of the polycrystalline BDD material. Notably, boron dopants were confirmed to be non-uniformly distributed over the BDD material, which is characterized by a distinct columnar structure and composition of grains of various orientations. Particularly, the highest electrochemical activity was recorded on the highest doped (111) crystal orientation. In contrast, the averagely boron-doped (100)-oriented facet showed non-conductive nature. This highlights that the local electrochemical activity of the BDD surface is strongly grain-dependent and the most significant factors governing the obtained responses are crystallographic orientation and boron doping. Moreover, increased boron and sp2 carbon content in the boundary regions was recognized by Raman mapping. However, such localized enrichment in impurities did not translate into enhanced electrochemical activity, which implies that boron atoms at the inter-grain areas are predominantly inactive. Finally, it is crucial to consider all characteristics of the polycrystalline BDD including crystal orientation, which is particularly relevant if micro- and nanoscale probing is intended.

Original languageEnglish
Article number119671
Number of pages12
JournalActa Materialia
Volume266
DOIs
Publication statusPublished - 2024

Funding

Financial support from the Dutch Research Council (NWO) through the Open Technology Programme [project no. 16361] is gratefully acknowledged. The authors are thankful to Kees Kwakernaak and Ruud Hendrikx (Department of Materials Science and Engineering, Delft University of Technology, The Netherlands) for their help with the EBSD and XRD measurements, respectively, and to Mintres B.V. (The Netherlands) for providing the free-standing, polycrystalline BDD electrodes.

Financial support from the Dutch Research Council (NWO) through the Open Technology Programme [project no. 16361 ] is gratefully acknowledged. The authors are thankful to Kees Kwakernaak and Ruud Hendrikx (Department of Materials Science and Engineering, Delft University of Technology, The Netherlands) for their help with the EBSD and XRD measurements, respectively, and to Mintres B.V. (The Netherlands) for providing the free-standing, polycrystalline BDD electrodes.

Keywords

  • Boron-doped diamond (BDD)
  • Electron backscatter diffraction
  • Grain boundaries
  • Raman mapping
  • Scanning electrochemical microscopy (SECM)

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