Tuning the density distribution of deep localized states of TiO 2 nanotube arrays through decoration with Pt and Pt@DLC
Creators: name: Shafiekhani, Azizollah
name: Zare, Maryam
name: Abdollah Mortezaali
Publisher: name: figshare
Year: 2020
Subjects: subject: 20301 Acoustics and Acoustical Devices; Waves
subject: FOS: Physical sciences
subject: FOS: Physical sciences
subject: Applied Physics
subject: Atomic Physics
subject: 20201 Atomic and Molecular Physics
subject: 20299 Atomic, Molecular, Nuclear, Particle and Plasma Physics not elsewhere classified
subject: 29901 Biological Physics
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: 20399 Classical Physics not elsewhere classified
subject: 20501 Classical and Physical Optics
subject: 29902 Complex Physical Systems
subject: 20302 Electrostatics and Electrodynamics
subject: 20404 Electronic and Magnetic Properties of Condensed Matter; Superconductivity
subject: 20601 Degenerate Quantum Gases and Atom Optics
subject: Entropy
subject: 20503 Nonlinear Optics and Spectroscopy
subject: 20202 Nuclear Physics
subject: 20599 Optical Physics not elsewhere classified
subject: 20203 Particle Physics
subject: 20504 Photonics, Optoelectronics and Optical Communications
subject: 29999 Physical Sciences not elsewhere classified
subject: Plasma Physics
subject: 20204 Plasma Physics; Fusion Plasmas; Electrical Discharges
subject: 20405 Soft Condensed Matter
subject: 91308 Solid Mechanics
subject: FOS: Mechanical engineering
subject: FOS: Mechanical engineering
subject: Special Relativity
subject: 20406 Surfaces and Structural Properties of Condensed Matter
subject: 29904 Synchrotrons; Accelerators; Instruments and Techniques
subject: Thermodynamics
subject: 20304 Thermodynamics and Statistical Physics

description: We demonstrate the possibility to tune the distribution of deep localized states and electronic transport properties of TiO 2 nanotube arrays (TNA)through decoration its surface with Pt or Pt@DLC (Diamond-like carbon). A quantitative calculation of the position of the deep trap states in the band gap and the amount of accumulated charge in deep traps of Pt/TNA and Pt-DLC/TNA electrodes are presented and compared based on photocurrent-voltage curves. Our findings demonstrate that both Pt NPs and Pt@DLC depositions could decrease the quantity of deep localized states in the band gap by saturating the dangling bonds on the surface of TNA. A decline in photoluminescence intensity in platinized samples confirmed the density of deep trap states acting as recombination centers reduced by these surface modifications. Also, the deep localized states in Pt/TNA and Pt-DLC/TNA electrodes shift down towards valence band, in comparison with pure TNA. The neighborhood of the trapped electrons in deep states to the hole sites (VB)in platinized samples leads to the reduction of the electron- hole life time in these samples. Moreover, higher anodic photocurrent density was observed for pure TNA, revealed that in pure TNA the free photoexcited electrons reached to the conduction band will transport to the external circuit whereas, in Pt/TNAs and Pt-DLC/TNAs some free electrons would transfer to Pt NPs via Schottky junction at the semiconductor/electrolyte interface or via hopping or tunneling of pi-electrons existing in the sp 2 nanoregions of DLC. Finally, Pt- and Pt@DLC-modified TNA electrodes absorbing light in the visible range and suppressing photoelectron recombination are worthy photocatalysts. In contrast, the deposition of Pt or Pt@DLC on TiO 2 nanotubes resulted in lower PEC response.