A novel one-step electrochemical method to obtain crystalline titanium dioxide films at low temperature

S. Karuppuchamy,N. Suzuki,S. Ito,T. Endo 한국물리학회 2009 Current Applied Physics Vol.9 No.1

A crystalline titanium dioxide (TiO2) thin film on various metal substrates such as hot-dip-galvanized (HDG), electrochemically galvanized (EG) and cold rolled steel (CRS) has been successfully prepared for the first time by simple one-step electrodeposition method from alkaline aqueous solution containing potassium titanium oxalate and hydroxylamine. The as-grown titanium dioxide films are composed of a mixture of anatase, rutile and brookite structures and have a good crystalline state. The present investigation reveals that the electrochemical deposition of crystalline titanium dioxide on different metal substrates from single electrochemical bath is possible and very promising as a preparation method for industrial applications. A crystalline titanium dioxide (TiO2) thin film on various metal substrates such as hot-dip-galvanized (HDG), electrochemically galvanized (EG) and cold rolled steel (CRS) has been successfully prepared for the first time by simple one-step electrodeposition method from alkaline aqueous solution containing potassium titanium oxalate and hydroxylamine. The as-grown titanium dioxide films are composed of a mixture of anatase, rutile and brookite structures and have a good crystalline state. The present investigation reveals that the electrochemical deposition of crystalline titanium dioxide on different metal substrates from single electrochemical bath is possible and very promising as a preparation method for industrial applications.

Synthesis and characterization of TiO2/MoO3/carbon clusters composite material

H. Matsui,S. Nagano,S. Karuppuchamy,M. Yoshihara 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Nano-sized TiO2/MoO3/carbon clusters composite material has been successfully obtained by the calcinations of a TiO(acac)2/MoO2(acac)2/epoxy resin complex under an oxygen atmosphere. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis and surface characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The ultraviolet–visible (UV–Vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. ESR spectra of the composite materials suggest that they have visible light-responsive catalytic ability with an electron transfer process of carbon clusters → MoO3 → carbon clusters → TiO2. Nano-sized TiO2/MoO3/carbon clusters composite material has been successfully obtained by the calcinations of a TiO(acac)2/MoO2(acac)2/epoxy resin complex under an oxygen atmosphere. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis and surface characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The ultraviolet–visible (UV–Vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. ESR spectra of the composite materials suggest that they have visible light-responsive catalytic ability with an electron transfer process of carbon clusters → MoO3 → carbon clusters → TiO2.

The electronic behaviors of visible light sensitive Nb2O5/Cr2O3/carbon clusters composite materials

H. Matsui,K. Kira,S. Karuppuchamy,M. Yoshihara 한국물리학회 2009 Current Applied Physics Vol.9 No.3

Nano-sized Nb2O5/Cr2O3/carbon clusters composite material has been successfully obtained by the calcination of a Nb(HC2O4)5/CrCl3/starch complex under an argon atmosphere. The compositions of the resulting composite materials were determined using ICP, elemental analysis and surface characterization by XRD and TEM. The UV–VIS and XPS spectra of the composites were also obtained. ESR spectral examinations suggest the possibility of an electron transfer in the process of Nb2O5→carbon clusters→Cr2O3. The reduction reaction of methylene blue with the resulting composite material has also been examined. Nano-sized Nb2O5/Cr2O3/carbon clusters composite material has been successfully obtained by the calcination of a Nb(HC2O4)5/CrCl3/starch complex under an argon atmosphere. The compositions of the resulting composite materials were determined using ICP, elemental analysis and surface characterization by XRD and TEM. The UV–VIS and XPS spectra of the composites were also obtained. ESR spectral examinations suggest the possibility of an electron transfer in the process of Nb2O5→carbon clusters→Cr2O3. The reduction reaction of methylene blue with the resulting composite material has also been examined.

The electronic behaviors of TiO2/MnO2/carbon clusters composite materials obtained by the calcination of a TiO(acac)2/Mn(acac)3/epoxy resin complex

H. Matsui,Y. Saito,S. Karuppuchamy,M. Yoshihara 한국물리학회 2009 Current Applied Physics Vol.9 No.6

The calcination of a TiO(acac)2/Mn(acac)3/epoxy resin complex under an oxygen atmosphere successfully produced nano-sized TiO2/MnO2/carbon clusters composite material. The surface characterizations of the resulting composites indicate that they are composed of nano-sized particles of TiO2, MnO2 and carbon clusters. ESR spectral examination suggests the possibility of an electron transfer in the process of MnO2→carbon clusters→TiO2. The visible light-responsive oxidation–reduction function of the composite materials has also been confirmed. The calcination of a TiO(acac)2/Mn(acac)3/epoxy resin complex under an oxygen atmosphere successfully produced nano-sized TiO2/MnO2/carbon clusters composite material. The surface characterizations of the resulting composites indicate that they are composed of nano-sized particles of TiO2, MnO2 and carbon clusters. ESR spectral examination suggests the possibility of an electron transfer in the process of MnO2→carbon clusters→TiO2. The visible light-responsive oxidation–reduction function of the composite materials has also been confirmed.

Electronic behavior of visible light sensitive ZrO2/Cr2O3/carbon clusters composite materials

H. Miyazaki,H. Matsui,Y. Kita,S. Karuppuchamy,S. Ito,M. Yoshihara 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Nano-sized ZrO2/Cr2O3/carbon clusters composite materials were successfully obtained by the microwave-irradiated calcinations of a Zr(acac)4/Cr(acac)3/epoxy resin complex. The compositions of the resulting composite materials were determined using ICP, elemental analysis and surface characterization by XRD, SEM and TEM. The UV–Vis spectra of the composites were also obtained. ESR spectral examinations of the composites indicate that an electron transfer takes place in the process Cr2O3 → carbon clusters → ZrO2. The composite materials have been found to show visible light-responsive catalytic activities. Nano-sized ZrO2/Cr2O3/carbon clusters composite materials were successfully obtained by the microwave-irradiated calcinations of a Zr(acac)4/Cr(acac)3/epoxy resin complex. The compositions of the resulting composite materials were determined using ICP, elemental analysis and surface characterization by XRD, SEM and TEM. The UV–Vis spectra of the composites were also obtained. ESR spectral examinations of the composites indicate that an electron transfer takes place in the process Cr2O3 → carbon clusters → ZrO2. The composite materials have been found to show visible light-responsive catalytic activities.

Electronic behavior of carbon clusters/hafnium oxide composite material

H. Matsui,T. Kuroda,T. Kawahara,S. Karuppuchamy,R. Kudoh,M. Yoshihara 한국물리학회 2009 Current Applied Physics Vol.9 No.1

An alternating hafnium-O-phenylene hybrid copolymer was calcined under the reduced pressure at 400–700 ℃ to obtain black-colored materials. XRD and TEM analyses showed that the calcined materials were composed of carbon clusters with the diameters of 20 nm and hafnium oxide particles with the diameters of a few nm. ESR spectral examinations revealed that the calcined materials formed a stable cation radical on the carbon clusters and exhibited an oxidation–reduction function. When Au particles were supported on the material, an efficient oxidation–reduction function was found to appear. An alternating hafnium-O-phenylene hybrid copolymer was calcined under the reduced pressure at 400–700 ℃ to obtain black-colored materials. XRD and TEM analyses showed that the calcined materials were composed of carbon clusters with the diameters of 20 nm and hafnium oxide particles with the diameters of a few nm. ESR spectral examinations revealed that the calcined materials formed a stable cation radical on the carbon clusters and exhibited an oxidation–reduction function. When Au particles were supported on the material, an efficient oxidation–reduction function was found to appear.

A vacuum pressure sensor based on graphene/ZnO nanorod Schottky junction

Sakthivel P.,Ramachandran K.,Malarvizhi M.,Karuppuchamy S.,Manivel P. 한국탄소학회 2024 Carbon Letters Vol.34 No.1

We present a practical vacuum pressure sensor based on the Schottky junction using graphene anchored on a vertically aligned zinc oxide nanorod (ZnO-NR). The constructed heterosystem of the Schottky junction showed characteristic rectifying behavior with a Schottky barrier height of 0.64 eV. The current–voltage (I–V) features of the Schottky junction were measured under various pressures between 1.0 × 103 and 1.0 × 10−3 mbar. The maximum current of 38.17 mA for the Schottky junction was measured at – 4 V under 1.0 × 10−3 mbar. The high current responses are larger than those of the previously reported vacuum pressure sensors based on ZnO nanobelt film, ZnO nanowires, and vertically aligned ZnO nanorod devices. The pressure-sensitive current increases with the vacuum pressure and reaches maximum sensitivity (78.76%) at 1.0 × 10−3 mbar. The sensitivity and repeatability of the Schottky junction were studied by the current–time (I–T) behavior under variation of vacuum pressure. The sensing mechanism is debated from the surface charge transfer doping effect by oxygen chemisorption. The results suggest that this simple graphene/ZnO-NR Schottky junction device may have potential in the fabrication of vacuum pressure sensor with high sensitivity.