Nilay Kumar Dey | K.B.N.I.M.S/K.I.M.S (original) (raw)
Papers by Nilay Kumar Dey
Growth of TiO2 films prepared by atomic layer deposition (ALD) was studied on C fiber. Moreover, ... more Growth of TiO2 films prepared by atomic layer deposition (ALD) was studied on C fiber. Moreover, adsorption and photocatalytic decomposition of methylene blue on TiO2 thin films were studied. Preferential growth of TiO2 on steps of C surfaces could be identified by scanning electron microscopy (SEM). X-ray Photoelectron Spectroscopy (XPS) showed thickness-dependent positive core level shift of Ti, which can be interpreted in terms of enhanced final state charging for thicker films. Adsorption and photocatalytic behaviors of TiO2 thin films will be discussed in this poster.
Catalysis Letters, 2010
We studied the adsorption of toluene and its photodecomposition by TiO2 surfaces under UV irradia... more We studied the adsorption of toluene and its photodecomposition by TiO2 surfaces under UV irradiation using P-25 samples subjected to two different treatments. In order to shed light on the elementary steps of the photocatalytic decomposition of toluene, we employed X-ray photoelectron spectroscopy (XPS). A higher population of the surface OH-group of TiO2 increased the adsorption reactivity and initial rate of the photodecomposition of toluene. We also identified more efficient accumulation of toluene on the surface of TiO2 with high concentrations of OH-groups via XPS.Graphical Abstract
CO2 reforming of methane (CRM) based on Ni catalysts was studied using temperature programmed rea... more CO2 reforming of methane (CRM) based on Ni catalysts was studied using temperature programmed reaction (TPR). The onset temperature of the CRM reaction was increased in a repeated TPR experiments. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy showed formation of graphite structures on Ni during CRM reaction, which deactivate Ni-surfaces. Attempts were made for inhibiting deactivation of Ni surfaces and reducing onset-temperature of the CRM reaction by various surface modification techniques, which will be presented in this poster.
The photocatalytic decomposition of toluene gas was investigated with TiO₂on nano-diamond powder ... more The photocatalytic decomposition of toluene gas was investigated with TiO₂on nano-diamond powder (NDP) under UV irradiation. Atomic layer deposition (ALD) was used for the growth of TiO₂on the NDP. The structure and surface properties of catalysts were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The photocatalytic activity for the toluene decomposition was evaluated by measuring the concentration change of toluene and CO 2 gas with gas chromatography (GC)-flame ionization detector (FID) system. The photocatalytic activities of TiO 2 /NDP catalysts were compared with that of P-25. The rate of initial photocatalytic decomposition of toluene for the TiO 2 /NDP catalysts was relatively lower when compared to P-25. The photocatalytic activity of P-25 was rapidly decreased with time, whereas, the deactivation of TiO 2 /NDP catalysts was less pronounced. Therefore, as the reaction time increased, the photocatalytic activity of TiO 2 /NDP catalysts became higher than that of P-25. The intermediates such as benzaldehyde or benzoic acid, etc were more easily adhered to the active site on the P-25 surface during reaction, resulting in easier deactivation of P-25. These results could be confirmed using FT-IR spectroscopy. We suggest that the NDP used as substrate can reduce the deactivation of TiO 2 on the surface.
Journal of Molecular Catalysis A-chemical, 2011
TiO 2 films were grown on carbon fiber by atomic layer deposition (ALD), and adsorption and photo... more TiO 2 films were grown on carbon fiber by atomic layer deposition (ALD), and adsorption and photocatalytic decomposition of methylene blue (MB) on these TiO 2 films were studied. They showed very high adsorption capacities of MB, indicating that these films can be used as adsorbents for removing organic dyes under dark conditions. The adsorption capacities of used TiO 2 films could be regenerated by light exposure through the photocatalytic degradation of the adsorbed MB.
Defect and Diffusion Forum
Absolute diffusion rates of KMnO4 in vertical and flattened diffusimeters show the concentration ... more Absolute diffusion rates of KMnO4 in vertical and flattened diffusimeters show the concentration gradient force as being stronger than the gravitational force. Hot water molecules move downward on self-diffusion against buoyancy. Diffusive convection (DC) in warm water and double-diffusive convection (DDC) in warm, saline water take place inside the diffusimeter with DDC transferring more heat than DC. In the diffusing medium the original reagents change or retain their compositions to give the diffusate molecules to diffuse. In water, the change is mostly hydration. The syngener BaCl2.2H2O separately with congeners 3CdSO4.8H2O, ZnSO4.7H2O, and ZnSO4.H2O presents two distinct pairs of overlapping concentration versus rate curves, first for having very close MWs of BaCl2 and CdSO4 and second for having ZnSO4.H2O as the common congener for both the zinc sulfates. Chlorides of Li, Na, and K diffusing at hindered rates in glucose solution show the least rate for LiCl inevitably on groun...
Bulletin of the Korean Chemical Society
Table 1. The second-order rate constants (kH(D) × 10 2 /M-1 s-1), selectivity parameters (ρX and ... more Table 1. The second-order rate constants (kH(D) × 10 2 /M-1 s-1), selectivity parameters (ρX and βX), a and deuterium kinetic isotope effects (kH/kD) for the reactions of diethyl phosphinic chloride (2) with XC6H4NH2(D2) in MeCN at 50.0 o C X kH × 10 2 /M-1 s-1 kD × 10 2 /M-1 s-1 kH/kD 4-MeO 44.4 ± 0.2 b 45.6 ± 0.6 0.974 ± 0.001 i 4-Me 29.
Bulletin of the Korean Chemical Society
Catalysis Letters, May 22, 2010
ABSTRACT Abstract We studied the adsorption of toluene and its photodecomposition by TiO2 surface... more ABSTRACT Abstract We studied the adsorption of toluene and its photodecomposition by TiO2 surfaces under UV irradiation using P-25 samples subjected to two different treatments. In order to shed light on the elementary steps of the photocatalytic decomposition of toluene, we employed X-ray photoelectron spectroscopy (XPS). A higher population of the surface OH-group of TiO2 increased the adsorption reactivity and initial rate of the photodecomposition of toluene. We also identified more efficient accumulation of toluene on the surface of TiO2 with high concentrations of OH-groups via XPS. Graphical Abstract
Surface and Interface Analysis, 2010
Behaviors of Pd structures with different thicknesses supported by Ta 2 O 5 /Ta in the reaction w... more Behaviors of Pd structures with different thicknesses supported by Ta 2 O 5 /Ta in the reaction with oxygen and CO were studied by XPS and SEM. For the samples with a Pd thickness of 3 nm, a new low-binding-energy component appeared in the Pd 3d level upon O 2 exposure at ∼200 • C and was reduced in intensity after a subsequent CO exposure at 150 and 200 • C. The change in the Ta 4f state could also be found upon oxygen and CO exposure, indicating that both Pd and the Ta-oxide substrate participate in the chemical reactions. For the sample with a higher Pd thickness, a positive shift in the Pd 3d level due to the oxidation of Pd was observed after exposure to O 2 at a higher temperature (280 • C). A subsequent CO exposure at ∼150 • C could not reduce Pd-oxide layers, as confirmed by the unchanged Pd 3d spectra after CO treatment, i.e. Pd-oxide was not reactive for CO oxidation.
Procedia Engineering, 2012
Nickel nanoparticles and thin film on carbon fiber have been prepared through electroless deposit... more Nickel nanoparticles and thin film on carbon fiber have been prepared through electroless deposition. Moreover, carbon nanotubes were grown on carbon fiber covered by nickel nanoparticles using thermal chemical vapor deposition. The effects of changes in the thickness of the nickel catalyst layer and the growth temperature of carbon nanotubes were studied systemically, and the results are discussed in the present work.
Catalysis Letters, 2011
Abstract Atomic layer deposition (ALD) was used to deposit TiO2 on Ni particles, and the catalyt... more Abstract Atomic layer deposition (ALD) was used to deposit TiO2 on Ni particles, and the catalytic activity of Ni for CO2 reforming of methane (CRM) was evaluated. In the presence of TiO2 islands on Ni surfaces, the onset temperature of the CRM reaction was lower than that of bare Ni. During the CRM reaction, carbon was deposited on the surface of
Applied Surface Science, 2011
TiO 2 was treated by water in an ultrasonic bath, resulting in the enhancement of the photocataly... more TiO 2 was treated by water in an ultrasonic bath, resulting in the enhancement of the photocatalytic activity for the decomposition of methylene blue under UV and visible light irradiation. No change in the crystallinity and optical properties of TiO 2 by the H 2 O-treatment was observed. ...
Applied Catalysis A: General, 2011
The photocatalytic decomposition of toluene gas was investigated using TiO 2 prepared by atomic l... more The photocatalytic decomposition of toluene gas was investigated using TiO 2 prepared by atomic layer deposition (ALD) on nanodiamond (ND) under UV irradiation. The photocatalytic activities of NDsupported TiO 2 catalysts were compared with that of P-25. The photocatalytic activity of P-25 was rapidly decreased with time due to the accumulation of reaction intermediates formed on the surface as a result of partial oxidation of toluene. Comparing to P-25, deactivation of ND-supported TiO 2 catalysts was less pronounced. It is suggested that ND surface facilitates total oxidation of toluene on TiO 2 and reduces poisoning of TiO 2 surface with time.
Bulletin of the Korean Chemical Society, 2007
The aminolysis of diphenyl thiophosphinic chloride (2) with substituted anilines in acetonitrile ... more The aminolysis of diphenyl thiophosphinic chloride (2) with substituted anilines in acetonitrile at 55.0 °C is investigated kinetically. Kinetic results yield large Hammett ρ x (ρ nuc = -3.97) and Bronsted β x (β nuc = 1.40) values. A concerted mechanism involving a partial frontside ...
Organic and …, Jan 1, 2007
Applied Physics …, Jan 1, 2011
Sung-Woo Cho,1 Young Tae Kim,1 Won Hyun Shim,1,2 Sun-Young Park,1 Kwang-Dae Kim,3 Hyun Ook Seo,3 ... more Sung-Woo Cho,1 Young Tae Kim,1 Won Hyun Shim,1,2 Sun-Young Park,1 Kwang-Dae Kim,3 Hyun Ook Seo,3 Nilay Kumar Dey,3 Jae-Hong Lim,1 Yongsoo Jeong,1 Kyu Hwan Lee,1 Young Dok Kim,3,a) and Dong Chan Lim1,a) 1Materials Processing Division, ...
Journal of Physical Organic …, Jan 1, 2008
The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC6H4ND2)... more The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC6H4ND2) are reported for the reactions of dimethyl chlorophosphate (1), dimethyl chlorothionophosphate (2), diethyl chlorophosphate (3) and diethyl chlorothionophosphate (4) in acetonitrile at ...
Org. Biomol. Chem., Jan 1, 2010
The reactions of Z-aryl dimethyl (1), methyl phenyl (2), and diphenyl (3) phosphinates with X-ani... more The reactions of Z-aryl dimethyl (1), methyl phenyl (2), and diphenyl (3) phosphinates with X-anilines in dimethyl sulfoxide at 60.0 °C are studied kinetically. Kinetic results yield the primary normal deuterium kinetic isotope effects (DKIEs) involving deuterated aniline (XC(6)H(4)ND(2)) nucleophiles, k(H)/k(D) = 1.03-1.17, 1.15-1.29, and 1.24-1.51, and the cross-interaction constants (CICs), ρ(XZ) = 0.37, 0.34, and 0.65 for 1, 2, and 3, respectively. The steric effects of the ligands (R(1) and R(2)) on reaction rates play a role, but are relatively much smaller compared to other phosphinate systems. A stepwise mechanism with a rate-limiting leaving group expulsion from the intermediate is proposed on the basis of the CICs positive signs. The dominant frontside nucleophilic attack through a hydrogen-bonded, four-center-type transition state is proposed on the basis of primary normal DKIEs and large magnitudes of the CICs for 2 and 3, while both frontside and backside attack are proposed on the basis of relatively small primary normal DKIEs for 1.
Journal of Molecular …, Jan 1, 2011
Growth of TiO2 films prepared by atomic layer deposition (ALD) was studied on C fiber. Moreover, ... more Growth of TiO2 films prepared by atomic layer deposition (ALD) was studied on C fiber. Moreover, adsorption and photocatalytic decomposition of methylene blue on TiO2 thin films were studied. Preferential growth of TiO2 on steps of C surfaces could be identified by scanning electron microscopy (SEM). X-ray Photoelectron Spectroscopy (XPS) showed thickness-dependent positive core level shift of Ti, which can be interpreted in terms of enhanced final state charging for thicker films. Adsorption and photocatalytic behaviors of TiO2 thin films will be discussed in this poster.
Catalysis Letters, 2010
We studied the adsorption of toluene and its photodecomposition by TiO2 surfaces under UV irradia... more We studied the adsorption of toluene and its photodecomposition by TiO2 surfaces under UV irradiation using P-25 samples subjected to two different treatments. In order to shed light on the elementary steps of the photocatalytic decomposition of toluene, we employed X-ray photoelectron spectroscopy (XPS). A higher population of the surface OH-group of TiO2 increased the adsorption reactivity and initial rate of the photodecomposition of toluene. We also identified more efficient accumulation of toluene on the surface of TiO2 with high concentrations of OH-groups via XPS.Graphical Abstract
CO2 reforming of methane (CRM) based on Ni catalysts was studied using temperature programmed rea... more CO2 reforming of methane (CRM) based on Ni catalysts was studied using temperature programmed reaction (TPR). The onset temperature of the CRM reaction was increased in a repeated TPR experiments. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy showed formation of graphite structures on Ni during CRM reaction, which deactivate Ni-surfaces. Attempts were made for inhibiting deactivation of Ni surfaces and reducing onset-temperature of the CRM reaction by various surface modification techniques, which will be presented in this poster.
The photocatalytic decomposition of toluene gas was investigated with TiO₂on nano-diamond powder ... more The photocatalytic decomposition of toluene gas was investigated with TiO₂on nano-diamond powder (NDP) under UV irradiation. Atomic layer deposition (ALD) was used for the growth of TiO₂on the NDP. The structure and surface properties of catalysts were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The photocatalytic activity for the toluene decomposition was evaluated by measuring the concentration change of toluene and CO 2 gas with gas chromatography (GC)-flame ionization detector (FID) system. The photocatalytic activities of TiO 2 /NDP catalysts were compared with that of P-25. The rate of initial photocatalytic decomposition of toluene for the TiO 2 /NDP catalysts was relatively lower when compared to P-25. The photocatalytic activity of P-25 was rapidly decreased with time, whereas, the deactivation of TiO 2 /NDP catalysts was less pronounced. Therefore, as the reaction time increased, the photocatalytic activity of TiO 2 /NDP catalysts became higher than that of P-25. The intermediates such as benzaldehyde or benzoic acid, etc were more easily adhered to the active site on the P-25 surface during reaction, resulting in easier deactivation of P-25. These results could be confirmed using FT-IR spectroscopy. We suggest that the NDP used as substrate can reduce the deactivation of TiO 2 on the surface.
Journal of Molecular Catalysis A-chemical, 2011
TiO 2 films were grown on carbon fiber by atomic layer deposition (ALD), and adsorption and photo... more TiO 2 films were grown on carbon fiber by atomic layer deposition (ALD), and adsorption and photocatalytic decomposition of methylene blue (MB) on these TiO 2 films were studied. They showed very high adsorption capacities of MB, indicating that these films can be used as adsorbents for removing organic dyes under dark conditions. The adsorption capacities of used TiO 2 films could be regenerated by light exposure through the photocatalytic degradation of the adsorbed MB.
Defect and Diffusion Forum
Absolute diffusion rates of KMnO4 in vertical and flattened diffusimeters show the concentration ... more Absolute diffusion rates of KMnO4 in vertical and flattened diffusimeters show the concentration gradient force as being stronger than the gravitational force. Hot water molecules move downward on self-diffusion against buoyancy. Diffusive convection (DC) in warm water and double-diffusive convection (DDC) in warm, saline water take place inside the diffusimeter with DDC transferring more heat than DC. In the diffusing medium the original reagents change or retain their compositions to give the diffusate molecules to diffuse. In water, the change is mostly hydration. The syngener BaCl2.2H2O separately with congeners 3CdSO4.8H2O, ZnSO4.7H2O, and ZnSO4.H2O presents two distinct pairs of overlapping concentration versus rate curves, first for having very close MWs of BaCl2 and CdSO4 and second for having ZnSO4.H2O as the common congener for both the zinc sulfates. Chlorides of Li, Na, and K diffusing at hindered rates in glucose solution show the least rate for LiCl inevitably on groun...
Bulletin of the Korean Chemical Society
Table 1. The second-order rate constants (kH(D) × 10 2 /M-1 s-1), selectivity parameters (ρX and ... more Table 1. The second-order rate constants (kH(D) × 10 2 /M-1 s-1), selectivity parameters (ρX and βX), a and deuterium kinetic isotope effects (kH/kD) for the reactions of diethyl phosphinic chloride (2) with XC6H4NH2(D2) in MeCN at 50.0 o C X kH × 10 2 /M-1 s-1 kD × 10 2 /M-1 s-1 kH/kD 4-MeO 44.4 ± 0.2 b 45.6 ± 0.6 0.974 ± 0.001 i 4-Me 29.
Bulletin of the Korean Chemical Society
Catalysis Letters, May 22, 2010
ABSTRACT Abstract We studied the adsorption of toluene and its photodecomposition by TiO2 surface... more ABSTRACT Abstract We studied the adsorption of toluene and its photodecomposition by TiO2 surfaces under UV irradiation using P-25 samples subjected to two different treatments. In order to shed light on the elementary steps of the photocatalytic decomposition of toluene, we employed X-ray photoelectron spectroscopy (XPS). A higher population of the surface OH-group of TiO2 increased the adsorption reactivity and initial rate of the photodecomposition of toluene. We also identified more efficient accumulation of toluene on the surface of TiO2 with high concentrations of OH-groups via XPS. Graphical Abstract
Surface and Interface Analysis, 2010
Behaviors of Pd structures with different thicknesses supported by Ta 2 O 5 /Ta in the reaction w... more Behaviors of Pd structures with different thicknesses supported by Ta 2 O 5 /Ta in the reaction with oxygen and CO were studied by XPS and SEM. For the samples with a Pd thickness of 3 nm, a new low-binding-energy component appeared in the Pd 3d level upon O 2 exposure at ∼200 • C and was reduced in intensity after a subsequent CO exposure at 150 and 200 • C. The change in the Ta 4f state could also be found upon oxygen and CO exposure, indicating that both Pd and the Ta-oxide substrate participate in the chemical reactions. For the sample with a higher Pd thickness, a positive shift in the Pd 3d level due to the oxidation of Pd was observed after exposure to O 2 at a higher temperature (280 • C). A subsequent CO exposure at ∼150 • C could not reduce Pd-oxide layers, as confirmed by the unchanged Pd 3d spectra after CO treatment, i.e. Pd-oxide was not reactive for CO oxidation.
Procedia Engineering, 2012
Nickel nanoparticles and thin film on carbon fiber have been prepared through electroless deposit... more Nickel nanoparticles and thin film on carbon fiber have been prepared through electroless deposition. Moreover, carbon nanotubes were grown on carbon fiber covered by nickel nanoparticles using thermal chemical vapor deposition. The effects of changes in the thickness of the nickel catalyst layer and the growth temperature of carbon nanotubes were studied systemically, and the results are discussed in the present work.
Catalysis Letters, 2011
Abstract Atomic layer deposition (ALD) was used to deposit TiO2 on Ni particles, and the catalyt... more Abstract Atomic layer deposition (ALD) was used to deposit TiO2 on Ni particles, and the catalytic activity of Ni for CO2 reforming of methane (CRM) was evaluated. In the presence of TiO2 islands on Ni surfaces, the onset temperature of the CRM reaction was lower than that of bare Ni. During the CRM reaction, carbon was deposited on the surface of
Applied Surface Science, 2011
TiO 2 was treated by water in an ultrasonic bath, resulting in the enhancement of the photocataly... more TiO 2 was treated by water in an ultrasonic bath, resulting in the enhancement of the photocatalytic activity for the decomposition of methylene blue under UV and visible light irradiation. No change in the crystallinity and optical properties of TiO 2 by the H 2 O-treatment was observed. ...
Applied Catalysis A: General, 2011
The photocatalytic decomposition of toluene gas was investigated using TiO 2 prepared by atomic l... more The photocatalytic decomposition of toluene gas was investigated using TiO 2 prepared by atomic layer deposition (ALD) on nanodiamond (ND) under UV irradiation. The photocatalytic activities of NDsupported TiO 2 catalysts were compared with that of P-25. The photocatalytic activity of P-25 was rapidly decreased with time due to the accumulation of reaction intermediates formed on the surface as a result of partial oxidation of toluene. Comparing to P-25, deactivation of ND-supported TiO 2 catalysts was less pronounced. It is suggested that ND surface facilitates total oxidation of toluene on TiO 2 and reduces poisoning of TiO 2 surface with time.
Bulletin of the Korean Chemical Society, 2007
The aminolysis of diphenyl thiophosphinic chloride (2) with substituted anilines in acetonitrile ... more The aminolysis of diphenyl thiophosphinic chloride (2) with substituted anilines in acetonitrile at 55.0 °C is investigated kinetically. Kinetic results yield large Hammett ρ x (ρ nuc = -3.97) and Bronsted β x (β nuc = 1.40) values. A concerted mechanism involving a partial frontside ...
Organic and …, Jan 1, 2007
Applied Physics …, Jan 1, 2011
Sung-Woo Cho,1 Young Tae Kim,1 Won Hyun Shim,1,2 Sun-Young Park,1 Kwang-Dae Kim,3 Hyun Ook Seo,3 ... more Sung-Woo Cho,1 Young Tae Kim,1 Won Hyun Shim,1,2 Sun-Young Park,1 Kwang-Dae Kim,3 Hyun Ook Seo,3 Nilay Kumar Dey,3 Jae-Hong Lim,1 Yongsoo Jeong,1 Kyu Hwan Lee,1 Young Dok Kim,3,a) and Dong Chan Lim1,a) 1Materials Processing Division, ...
Journal of Physical Organic …, Jan 1, 2008
The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC6H4ND2)... more The deuterium kinetic isotope effects (KIEs) involving deuterated aniline nucleophiles (XC6H4ND2) are reported for the reactions of dimethyl chlorophosphate (1), dimethyl chlorothionophosphate (2), diethyl chlorophosphate (3) and diethyl chlorothionophosphate (4) in acetonitrile at ...
Org. Biomol. Chem., Jan 1, 2010
The reactions of Z-aryl dimethyl (1), methyl phenyl (2), and diphenyl (3) phosphinates with X-ani... more The reactions of Z-aryl dimethyl (1), methyl phenyl (2), and diphenyl (3) phosphinates with X-anilines in dimethyl sulfoxide at 60.0 °C are studied kinetically. Kinetic results yield the primary normal deuterium kinetic isotope effects (DKIEs) involving deuterated aniline (XC(6)H(4)ND(2)) nucleophiles, k(H)/k(D) = 1.03-1.17, 1.15-1.29, and 1.24-1.51, and the cross-interaction constants (CICs), ρ(XZ) = 0.37, 0.34, and 0.65 for 1, 2, and 3, respectively. The steric effects of the ligands (R(1) and R(2)) on reaction rates play a role, but are relatively much smaller compared to other phosphinate systems. A stepwise mechanism with a rate-limiting leaving group expulsion from the intermediate is proposed on the basis of the CICs positive signs. The dominant frontside nucleophilic attack through a hydrogen-bonded, four-center-type transition state is proposed on the basis of primary normal DKIEs and large magnitudes of the CICs for 2 and 3, while both frontside and backside attack are proposed on the basis of relatively small primary normal DKIEs for 1.
Journal of Molecular …, Jan 1, 2011