Achievement and electrochemical responsiveness of advanced boron-doped ultrananocrystalline diamond on highly ordered titanium dioxide nanotubes

• Published in: Diamond and related materials 2022-01, Vol.121, p.108793, Article 108793
• Main Authors: Vernasqui, Laís G., Kawata, Bianca A., Sardinha, A.F., Rodrigo, Manuel A., Ferreira, Neidenêi G.
• Format: Article
• Language: English
• Subjects: Boron; Boron-doped ultrananocrystalline diamond; Chemical vapor deposition; Composite; CVD growth without seeding; Diamonds; Diffusion layers; Doped films; Nanoclusters; Nanotubes; Porous walls; Raman spectra; Titanium carbide; Titanium dioxide; Titanium dioxide nanotubes
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2021.108793

Boron-doped ultrananocrystalline diamond grown on titanium dioxide nanotubes without seeding pre-treatment (B-UNCDWS/TDNT/Ti), as a porous composite, was successfully achieved. Innovative approaches concerning the highly ordered TDNT production as well as its singular diamond formation by hot filament chemical vapor deposition (CVD) were explored. The B-UNCD homogeneous cluster progress on the TDNT porous walls as a function of the growth times from 1 to 7 h led to remarkable composite morphologies, keeping the TDNT porosity, where the TiO2 – TiC conversion dominated the renucleation process facilitating the nanometric scale control. Scanning electron microscopy images confirmed the continuous ultrananocrystalline formation as nanoclusters on the TDNT walls with their size evolution as a function of growth time also showing an increase in the CVD diamond ballas clusters. Raman spectra and X-Ray patterns exhibited the diamond characteristics with defined peaks and TiC formation, as expected. The ID(220)/(111) and ID(311)/(111) ratio intensities pointed out the films governed by (220) diamond phase, due to their high renucleation process. Besides, the intensity ratios for both TiC (111) and TiC (200) phases with D(111) peak showed a carbon atoms competition between surface and bulk diffusion on the TiC layer. The electrode reversibility evaluated from cyclic voltammetry curves followed the quasi-reversible criteria for all samples, confirming their promising performance. Mott-Shottky plots are in good agreement with Raman spectra for boron-doped films from 1018 to 1019 B.cm−3 where the highest doped diamond was obtained for the thickest films of 5 and 7 h. [Display omitted] •B-UNCDWS/TDNT/Ti electrodes without seeding pre-treatment were successfully achieved.•The TDNT influence on UNCDWS formation is motivated by the TiO2 into TiC conversion.•SEM images showed a unique morphology with evolution as a function of growth time.•CVD ballas cluster were growth concomitantly, also a function of growth time.•The quasi-reversible behavior for all samples makes it a promising composite.