Recently, we reported on the phenomena of the formation of the novel composite material based on titania nanotubes (TiO₂ NTs) over-grown by thin boron-doped diamond (BDD) produced in microwave plasma enhanced chemical vapor deposition (MW PE CVD) [1,2]. Under microwave plasma treatment, the structure TiO₂ NTs underwent transformation from stoichiometric anatase into non-stochiometric oxide with Ti(III) phase and some rutile phase arises. Furthermore, obtained material was characterized with a significantly enhanced conductivity and capacitance comparing to pristine titania. The electrochemical studies showed that the specific areal capacitance of TiO₂/BDD raised up to 7.46 mF cm^-2 whereas for the pure BDD it reached only 0.11 7.46 mF cm^-2.

Because of such strong modification of titania and application potential in energy storage devices we decided to initiate growth of boron nanocrystalline diamond (B-NDC) on the highly ordered TiO₂ nanotube arrays. TiO₂ NTs are fabricated via two-step anodization of titanium metal plate followed by a short immersion in diluted HF in order to remove any surface debris [3]. Titanium plate covered by uniform titania nanotube layer provides a large specific surface area as well as a direct pathway for charge transport, thus holding promising capabilities of being support for another materials deposition. Afterwards, similarly to formation of TiO₂NTs/BDD material, the deposition of boron nanocrystalline diamond will be also realized under microwave plasma conditions and Ti/TiO₂ NTs will act as a substrate. The morphology and the structure of obtained composite material will be investigated using scanning electron microscopy and Raman spectroscopy. Electrochemical activity will be identified applying cyclic voltammetry and electrochemical impedance spectroscopy techniques performed in aqueous electrolyte. The influence of boron-doping level will be observed as a change in registered capacitive current and impedance behaviour.

References:

[1] K. Siuzdak, R. Bogdanowicz, M. Sawczak, M. Sobaszek, Enhanced capacitance of composite TiO₂ nanotube/boron-doped diamond electrodes studied by impedance spectroscopy, Nanoscale 7 (2015) 551

[2] M. Sawczak, M. Sobaszek, K. Siuzdak, J. Ryl, R. Bogdanowicz, K. Darowiski, M. Gazda, A. Cenian, Formation of highly conductive boron-doped diamond on TiO₂ nanotubes composite for supercapacitor or energy storage devices, J Electrochem Soc 162 (2015) A2085

[3] M. Szkoda, K. Siuzdak, A. Lisowska-Oleksiak, J. Karczewski, J. Ryl, Facile preparation of extremely photoactive boron-doped TiO₂ nanotube arrays, Electrochem Comm. 60 (2015) 212

Financial support from the Polish National Science Center – under grant No. 2012/07/D/ST5/02269 and No. 2011/03/D/ST7/03541 is gratefully acknowledged.