Formation of Highly Conductive Boron-Doped Diamond on TiO₂Nanotubes Composite for Supercapacitor or Energy Storage Devices

Abstract

In the present paper, we report the phenomena of the formation of the novel composite nanostructures based on TiO 2 nanotubes (NTs) over-grown by thin boron-doped diamond (BDD) film produced in Microwave Plasma Enhanced Chemical Vapor Deposition (PE MWCVD). The TiO 2 nanotube array overgrown by boron-doped diamond immersed in 0.1 M NaNO 3 can deliver high specific capacitance of 7.46 mF cm −2 . The composite electrodes were characterized by scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. The depth-resolved investigations reveal that the primary anatase structure of TiO 2 NTs was partially transformed into Ti 2 O 3 and non-stoichiometric TiC fractions. The explanation for this effect is the decomposing of TiO 2 NTs in the presence of activated hydrogen and carbon in the plasma leading to enhanced dehydration of NTs and carbon bonding originating from dissociated methane. This phenomena description fits also to processes demonstrated at hydrogenated TiO 2 (H-TiO 2 ) nanotube arrays used as electrode material for supercapacitors. Nevertheless, the increase of electrochemical performance can be attributed to several reasons: (1) the unique morphology of titania nanotubes and columnar BDD with intergrain defects and valley increasing specific area of electrode and (2) presence of TiC and Ti 2 O 3 fractions introducing additional capacitance.Nowadays, the world is directed towards green energy and its efficient storage. Supercapacitors are notably useful due to the highly reversible charge storage process, long cycle-life and ability of rapid charging and discharging. 1 Presently, the supercapacitors are divided into two main types: electrical double layer capacitors (EDLC) 2 and redox supercapacitors (pseudocapacitors), followed by Faradic reactions carried out at the electrode material. 3 Moreover, they can store substantially more energy than conventional capacitors due to the very small distance of charge separation in the electrical double layer and highly extended surface area of electrode material. 4 EDLC provide far larger charging and discharging times than typical capacitors or batteries up to 10 −6 s, charge/discharge efficiency close to ∼100% and nearly infinite cycle-life. 4 The titania nanotubes provide a large specific surface area, a direct pathway of charge transport but the specific capacitances are generally limited to less than 1 mF cm −2 without intentional doping or treatment. Lu and Li et al. 5,6 reported that hydrogenated TiO 2 by heating in hydrogen atmosphere resulted in an improvement of specific capacitance up to 3.24 mF cm −2 . Moreover, Wang and Leshuk et al. 7,8 received similar hydrogenated TiO 2 under hydrogen plasma treatment.Recently, there is interest in synthesis of a different type of titania/carbon composite materials such as nanotubes, 9-12 and porous titanium carbides 13,14 which showed the enhanced effectiveness of those materials in photocatalysis, 15 electrochemical biosensing, 16 photolum...

Laser-Assisted Synthesis and Oxygen Generation of Nickel Nanoparticles

“…Based on the proposed deconvolution, the share of the dehydrated NiO in the TiO 2 NTs decorated with NiNPs is around 20%. However, it should be noted that the observed change is not parallel with the modification of TiO 2 chemistry, based on recorded Ti2p spectra ( Figure 4 d), with Ti2p 3/2 peaking at 459.0 eV [ 61 , 62 ]. Finally, the O1s spectra for Ni colloid ( Figure 4 b) reveal the presence of multiple components; therefore, two spectral components were proposed for deconvolution.…”

Nano‐engineered Diamond‐based Materials for Supercapacitor Electrodes: A Review

“…The active surface area of TiO 2 NT/BDD‐10k was 1062 cm 2 . The detailed studies on the origin of the enhanced electrochemical activity of fabricated titania‐based diamond composites showed that such promising capacitive properties could be attributed to two main factors. The first concerns the specific architecture of TiO 2 NT, which provides a high real surface area and straight path for charge percolation, whereas the second is related to the modification of the titania structure induced by BDD coverage during the microwave plasma enhanced chemical vapor deposition (MWPE‐CVD) process involving: partial transformation from anatase to the rutile phase, Ti−C bonding that improves integration between titania and BDD, and the appearance of Ti 3+ , which affects the sample conductivity.…”

“…Titania nanotubes (TiO 2 NT) modified by boron‐doped diamond is a promising candidate for the fabrication of supercapacitors . On the contrary to Shi et al., the highly ordered layer of titania (8 μm in length and 30 nm in internal diameter) was produced by anodization of a Ti metal plate serving as a substrate for BDD growth (Figure A) during the CVD process with different diborane concentrations in the gas phase (B/C ratio equals 2000, 5000, and 10 000).…”

“…Various approaches have been utilized to achieve diamond nanostructuring, including selective top‐down etching and bottom‐up growth. The relevant fabrication methods for increasing the diamond surface area are shown in Figure . There are four common approaches for the preparation of nanostructured diamond electrodes: (i) nanodiamond‐based composites, (ii) porous CVD diamond, (iii) CVD diamond grown on Si nanowires (NWs), and (iv) CVD diamond composites.…”

“…Reproduced with permission from Refs. . Copyright 2015, Elsevier, MPDI, The Electrochemical Society, and American Chemical Society.…”