Vit Kalousek - Academia.edu (original) (raw)
Papers by Vit Kalousek
SID Symposium Digest of Technical Papers
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
SID Symposium Digest of Technical Papers, 2021
Inorganica Chimica Acta, 2018
We synthesized novel 4,4′-diamino-2,2′-bipyridine (dabpy) complexes of Cu(II), Co(III), and Ni(II... more We synthesized novel 4,4′-diamino-2,2′-bipyridine (dabpy) complexes of Cu(II), Co(III), and Ni(II), and determined their molecular structures by single-crystal XRD analysis. As a result, we found that [Cu(dabpy) 2 ] 2+ had a four-coordinated Cu center and distorted square-planar geometry, while the Co(III) and Ni(II) complexes contained six-coordinated metal centers and exhibited an octahedral geometry. The prepared complexes were investigated as co-catalysts for H 2 evolution from aqueous media in the presence of erythrosin B as a photosensitizer. Notably, the Cu(II) complex demonstrated a much higher co-catalyst activity than the corresponding Co(III) and Ni(II) species. Additionally, the H 2 evolution mechanism and the redox potentials of the metal dabpy complexes were elucidated using electrochemical studies, and it was found that the reduction of protons to H 2 was accompanied by a Cu(II)/Cu(I) redox reaction. In addition, it was suggested that the high co-catalyst activity of the Cu(II) complex was due to the low protonation-induced overpotential compared to those of Co(III) and Ni (II). Furthermore, the photo-sensitized H 2 evolution activity of the metal complex/K 2 PtCl 4 mixed systems were shown to exceed that of the K 2 PtCl 4-only control system. The Cu(II) complex was found to be low-cost and effective co-catalyst for homogeneous H 2 evolution system.
Journal of Solid State Chemistry, 2019
Fe-based oxides with bimodal pores in the meso-and macro-size range were synthesized using spheri... more Fe-based oxides with bimodal pores in the meso-and macro-size range were synthesized using spherical porous polymer monolith templates containing bicontinuous pore structures for use as a CO 2 adsorbent. The porous K-Al-Fe-based oxides showed higher CO 2 adsorption capacity than the corresponding non-porous sample. Lowering the calcination temperature during porous K-Al-Fe-based oxide synthesis from 900 C to 450 C led to further increases in CO 2 adsorption capacity. The CO 2 adsorption capacity of this porous K-Al-Fe-based oxide was significantly enhanced after H 2 O vapor treatment. FT-IR analysis showed that the treatment allowed for the formation of an additional CO 2 capture species. The improved CO 2 adsorption capacity was due to the change in the adsorption mode of CO 2 from the monodentate carbonate to a bicarbonate after a reaction with H 2 O vapor. The thermal and structural stability of the porous K-Al-Fe-based oxide was maintained even after treatment in H 2 O vapor.
![Research paper thumbnail of Carbon-Nanotube-based photocatalysts for Water Splitting in Cooperation with BiVO4 and [Co(bpy)3]3+/2+](https://attachments.academia-assets.com/90052166/thumbnails/1.jpg)
](Chemistry Letters, 2019
Physical modifications of single-walled carbon nanotubes (SWCNTs) with fullerodendrons, followed ... more Physical modifications of single-walled carbon nanotubes (SWCNTs) with fullerodendrons, followed by complexation with RuCl 3 leads to the formation of CNT-photocatalysts that exhibit high quantum yields (QY = 12.8%) for the production of H 2 from water, even under illumination with NIR light (λ irr = 1005 nm) in the presence of sacrificial donor. A Z-scheme photocatalytic system, consisting of such a CNT-photocatalyst, BiVO 4 , and [Co(bpy) 3 ] 3+/2+ shows a production of H 2 (17 mol/h) and O 2 (5.5¯mol/h) under illumination from a solar simulator (AM-1.5) with a solar-to-hydrogen (STH) efficiency of 0.089%.
Materials Letters, 2017
A low-cost photocatalytic system using a nickel-mercaptoethanol complex (Ni-ME) with a polymeric ... more A low-cost photocatalytic system using a nickel-mercaptoethanol complex (Ni-ME) with a polymeric structure and graphitic carbon nitride (g-C 3 N 4) for a hydrogen evolution reaction in the presence of triethanolamine (TEOA) as a sacrificial agent has been studied. To the best of our knowledge, this is the first study on this topic. We have found that 0.44 wt% Ni-ME/g-C 3 N 4 system exhibits the highest photocatalytic performance with high stability. There is an induction period between the first H 2 evolution and the main acceleration of the reaction. The crystalline Ni-ME on g-C 3 N 4 was converted into an amorphous phase, which was a more stable and active Ni complex for the photocatalytic reaction. Ni-ME/g-C 3 N 4 is easy to prepare and is economically effective for solar hydrogen evolution.
Chemical Physics Letters, 2017
K-Al-based mixed oxides (KAl 6 O 9.5) with mullite structures were synthesized as CO 2 adsorption... more K-Al-based mixed oxides (KAl 6 O 9.5) with mullite structures were synthesized as CO 2 adsorption materials using a polymerized complex method. Al 3+ sites in the octahedral AlO 6 units of K-Al-based mixed oxides were substituted with various metal ions with +2 or +3 valence states to enhance basicity. Among these samples, the Fe-introduced sample (KAl 5.5 Fe 0.5 O 9.5) showed 130 times higher CO 2 adsorption capacity than that of Li 4 SiO 4. Raman spectra of these samples indicated that large distortions of the AlO 6 unit were observed only for the Fe-introduced sample. Local polarization caused by such distortions could induce increased basicity of this sample.
ChemSusChem, 2014
Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be h... more Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be harnessed as an alternate fuel source, which paves the way to a clean-energy future. A photoelectrochemical (PEC) system with a Nb:SrTiO3 photoelectrode for oxygen evolution from an aqueous electrolyte and a Pt/C electrode for toluene (TL) hydrogenation to MCH was investigated under UV irradiation. A Nb:SrTiO3 single-crystal electrode and an ionomer/Pt/C membrane-electrode assembly (MEA) were used as the photoanode and cathode, respectively. A steady-state current density of 0.12 mA cm(-2) was observed for the two-electrode system without any bias voltage for >2 h, and a Faradaic efficiency of 97% was obtained for MCH production from TL. This is the first demonstration of the production of MCH from TL and water using only light energy. This means that light energy was converted directly into MCH from TL and water without any electricity. The PEC properties of the devices are discussed.
Superlattices and Microstructures, 2008
... [7] S. Barman and L. Philip, Environ. Sci. Technol. 40 (2006), p. 1035. Full Text via CrossRe... more ... [7] S. Barman and L. Philip, Environ. Sci. Technol. 40 (2006), p. 1035. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (14). [8] JS Dalton, PA Janes, NG Jones, JA Nicholson, KR Hallam and GC Allen, Environ. Pollut. 120 (2002), p. 415. ...
Photochem. Photobiol. Sci., 2011
We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is... more We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is based on spraying a sol containing titanium alkoxide, concentrated HCl, a suitable block-copolymer serving as a structure directing agent and a solvent, the viscosity of the spraying sol and the conditions of spraying being precisely adjusted in order to achieve uniform coverage of the surface. The thickness of the films can be readily controlled by varying the number of deposited layers, their porosity being homogeneous and their surface area and pore volume increasing practically linearly with the increasing number of deposited layers. The mesoporous films of TiO 2 are highly promising photocatalysts for the oxidation of NO at low concentrations and the removal of liquid layers deposited on their surface.
Langmuir, 2014
Nanometric thin films were prepared by dip-coating and inkjet printing ZnO nanosheets on glass pl... more Nanometric thin films were prepared by dip-coating and inkjet printing ZnO nanosheets on glass plates. The side-by-side alignment of the ZnO nanosheets on the substrate resulted in thin, transparent, oriented ZnO surfaces with the high-energy {001} facets exposed. The method of nanosheet deposition affected the film morphology; the dip-coated films were very smooth and nonporous, while the inkjet-printed films were rough and porous with the estimated void volume approximately 60−70% of the total film volume. The first-order rate constants for the photocatalytic degradation of 4-chlorophenol on the nanosheet-based films were approximately 2 times larger than those on nanocolumnar ZnO films or ZnO films prepared by the sol−gel technique. We attribute the high photocatalytic activity of the ZnO nanosheets to the fact that their {001} facets were predominantly exposed to the oxidized substrate. This surface arrangement and the simplicity of fabricating the ZnO nanosheet-based films make them promising for the construction of optical devices and dye-sensitized solar cells.
Journal of the American Chemical Society, 2010
Ultrasmall and highly soluble anatase nanoparticles were synthesized from TiCl 4 using tertbutyl ... more Ultrasmall and highly soluble anatase nanoparticles were synthesized from TiCl 4 using tertbutyl alcohol as a new reaction medium. This synthetic protocol widens the scope of nonaqueous sol-gel methods to TiO 2 nanoparticles of around 3 nm with excellent dispersibility in ethanol and tert-butanol. Microwave heating was found to enhance the crystallinity of the nanoparticles and to drastically shorten the reaction time to less than 1 h at temperatures as low as 50°C. The extremely small size of the nanoparticles and their dispersibility make it possible to use commercial Pluronic surfactants for evaporationinduced self-assembly of the nanoparticulate building blocks into periodic mesoporous structures. A solution of particles after synthesis can be directly used for preparation of mesoporous films without the need for particle separation. The mesoporous titania coatings fabricated using this one-pot procedure are crystalline and exhibit high surface areas of up to 300 m 2 /g. The advantages of the retention of the mesoporous order with extremely thin nanocrystalline walls were shown by electrochemical lithium insertion. The films made using microwave-treated nanoparticles showed supercapacitive behavior with high maximum capacitance due to quantitative lithiation with a 10-fold increase of charging rates compared to a standard reference electrode made from 20 nm anatase particles.
Journal of Photochemistry and Photobiology A: Chemistry, 2010
We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is... more We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is easy to use and applicable for objects of various shape and size. This technique is based on spraying a sol containing titanium alkoxide, HCl, a suitable block-copolymer serving as a structure directing agent, and a solvent. Both the viscosity of the sol and the spraying conditions were precisely adjusted in order to achieve uniform coverage of the surface. The thickness of the films can be readily controlled by varying the number of deposited layers, their porosity being homogeneous and their surface area and pore volume increasing practically linearly with the increasing number of deposited layers. The mesoporous films of TiO 2 are suitable photocatalysts for the oxidation of NO and the removal of liquid layers deposited on their surface. The effect of the flow rate of the gaseous mixture through the reactor on the photocatalytic conversion of NO was analyzed.
Journal of Hazardous Materials, 2012
A series of mesoporous films of titania of different thicknesses are prepared and their surface a... more A series of mesoporous films of titania of different thicknesses are prepared and their surface areas and porosities determined by physical adsorption using Kr as the adsorbate. The amounts of acid orange 7 (AO7) adsorbed by these films are found to be proportional to their measured surface areas and so the possibility of using this as a method of determining the surface area of thin titania films is discussed. The initial rates of UV-driven photocatalytic-and visible-driven photosensitised-bleaching of AO7 in solution, upon UVA and visible light irradiation, respectively, are also directly dependent upon the measured surface areas of the titania films. The quantum efficiencies for the UV photocatalytic-and visible photosensitised-bleaching of AO7 by the thickest of the AO7 films were estimated to be 0.08 and 0.01%, respectively.
Chemistry of Materials, 2009
Titania-silica composite films with a high content of crystalline titania phase and periodic meso... more Titania-silica composite films with a high content of crystalline titania phase and periodic mesoporous structure were fabricated by a low temperature "brick and mortar" approach. Pre-formed titania nanocrystals were fused with surfactant-templated sol-gel silica, which acts as a structure-directing matrix and as a chemical glue. The nature of the surfactant plays the decisive role in the mesostructure formation. Using Pluronic P123 as the structure-directing agent, the structure formation of the mesoporous silica is greatly disturbed as a result of the presence of titania nanoparticles. On the contrary, the use of Pluronic F127, whose molecules are larger and whose poly(ethylene oxide) blocks are more hydrophilic, enables the preparation of composite titania-silica mesoporous architectures that can accommodate up to 50 wt % of nanocrystals and yet retain the periodicity of the porous structure. In this way, films with a high degree of crystallinity were obtained at temperatures as low as 100-150°C and employed as active layers for the photooxidation of NO. The surface of the titania particles is not deactivated with respect to their photocatalytic activity by the surrounding silica matrix or by covalently attached ligands. The "brick and mortar" approach results in periodic mesoporous nanocomposites with photocatalytically active sites leading to functional coatings that are processed at low temperatures and thus opens new perspectives for their applicability on a wide range of substrates.
Chemistry of Materials, 2009
We present a novel "brick and mortar" strategy for creating highly efficient transparent TiO 2 co... more We present a novel "brick and mortar" strategy for creating highly efficient transparent TiO 2 coatings for photocatalytic and photovoltaic applications. Our approach is based on the fusion of preformed titania nanocrystalline "bricks" through surfactant-templated sol-gel titania "mortar", which acts as a structuredirecting matrix and as a chemical glue. The similar chemical composition of both bricks and mortar leads to a striking synergy in the interaction of crystalline and amorphous components, such that crystallization is enhanced upon thermal treatment and highly porous and highly crystalline structures are formed at very mild conditions. Coatings with a broad variety of periodic mesostructures and thicknesses ranging from few nanometers to several micrometers are accessible using the same organic template, and the final structures are tunable by varying the fraction of the "bricks". The beneficial combination of crystallinity and porosity leads to greatly enhanced activity of the films in photocatalytic processes, such as the photooxidation of NO. Acting as the active layers in dye-sensitized solar cells, films of only 2.7 µm in thickness exhibit a conversion efficiency of 6.0%.
Catalysis Today, 2014
Anatase TiO 2 coatings were grown on electrospun polymeric nanofibers (polyamide 6, polystyrene, ... more Anatase TiO 2 coatings were grown on electrospun polymeric nanofibers (polyamide 6, polystyrene, and polyurethane) via heterogeneous nucleation in an acidic aqueous solution of titanium oxysulfate at 60 • C. X-ray diffraction patterns confirmed a nanocrystalline anatase structure, and scanning electron microscopy observations revealed continuous coverage of the nanofiber surfaces by TiO 2. The morphology of the TiO 2 coatings was affected by the nature of the polymer. In all cases, the coatings generated hydroxyl radicals when irradiated with ultraviolet radiation. The materials were used for the photocatalytic oxidative removal of gaseous NO from air under irradiation at 365 nm. The functionalized polyamide 6 and polystyrene nanofibers were the most effective materials for converting NO to NO 2 and HNO 3. Based on our results, the anatase-coated nanofibers are promising materials for the removal of NO x pollutants from air.
SID Symposium Digest of Technical Papers
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
SID Symposium Digest of Technical Papers, 2021
Inorganica Chimica Acta, 2018
We synthesized novel 4,4′-diamino-2,2′-bipyridine (dabpy) complexes of Cu(II), Co(III), and Ni(II... more We synthesized novel 4,4′-diamino-2,2′-bipyridine (dabpy) complexes of Cu(II), Co(III), and Ni(II), and determined their molecular structures by single-crystal XRD analysis. As a result, we found that [Cu(dabpy) 2 ] 2+ had a four-coordinated Cu center and distorted square-planar geometry, while the Co(III) and Ni(II) complexes contained six-coordinated metal centers and exhibited an octahedral geometry. The prepared complexes were investigated as co-catalysts for H 2 evolution from aqueous media in the presence of erythrosin B as a photosensitizer. Notably, the Cu(II) complex demonstrated a much higher co-catalyst activity than the corresponding Co(III) and Ni(II) species. Additionally, the H 2 evolution mechanism and the redox potentials of the metal dabpy complexes were elucidated using electrochemical studies, and it was found that the reduction of protons to H 2 was accompanied by a Cu(II)/Cu(I) redox reaction. In addition, it was suggested that the high co-catalyst activity of the Cu(II) complex was due to the low protonation-induced overpotential compared to those of Co(III) and Ni (II). Furthermore, the photo-sensitized H 2 evolution activity of the metal complex/K 2 PtCl 4 mixed systems were shown to exceed that of the K 2 PtCl 4-only control system. The Cu(II) complex was found to be low-cost and effective co-catalyst for homogeneous H 2 evolution system.
Journal of Solid State Chemistry, 2019
Fe-based oxides with bimodal pores in the meso-and macro-size range were synthesized using spheri... more Fe-based oxides with bimodal pores in the meso-and macro-size range were synthesized using spherical porous polymer monolith templates containing bicontinuous pore structures for use as a CO 2 adsorbent. The porous K-Al-Fe-based oxides showed higher CO 2 adsorption capacity than the corresponding non-porous sample. Lowering the calcination temperature during porous K-Al-Fe-based oxide synthesis from 900 C to 450 C led to further increases in CO 2 adsorption capacity. The CO 2 adsorption capacity of this porous K-Al-Fe-based oxide was significantly enhanced after H 2 O vapor treatment. FT-IR analysis showed that the treatment allowed for the formation of an additional CO 2 capture species. The improved CO 2 adsorption capacity was due to the change in the adsorption mode of CO 2 from the monodentate carbonate to a bicarbonate after a reaction with H 2 O vapor. The thermal and structural stability of the porous K-Al-Fe-based oxide was maintained even after treatment in H 2 O vapor.
Chemistry Letters, 2019
Physical modifications of single-walled carbon nanotubes (SWCNTs) with fullerodendrons, followed ... more Physical modifications of single-walled carbon nanotubes (SWCNTs) with fullerodendrons, followed by complexation with RuCl 3 leads to the formation of CNT-photocatalysts that exhibit high quantum yields (QY = 12.8%) for the production of H 2 from water, even under illumination with NIR light (λ irr = 1005 nm) in the presence of sacrificial donor. A Z-scheme photocatalytic system, consisting of such a CNT-photocatalyst, BiVO 4 , and [Co(bpy) 3 ] 3+/2+ shows a production of H 2 (17 mol/h) and O 2 (5.5¯mol/h) under illumination from a solar simulator (AM-1.5) with a solar-to-hydrogen (STH) efficiency of 0.089%.
Materials Letters, 2017
A low-cost photocatalytic system using a nickel-mercaptoethanol complex (Ni-ME) with a polymeric ... more A low-cost photocatalytic system using a nickel-mercaptoethanol complex (Ni-ME) with a polymeric structure and graphitic carbon nitride (g-C 3 N 4) for a hydrogen evolution reaction in the presence of triethanolamine (TEOA) as a sacrificial agent has been studied. To the best of our knowledge, this is the first study on this topic. We have found that 0.44 wt% Ni-ME/g-C 3 N 4 system exhibits the highest photocatalytic performance with high stability. There is an induction period between the first H 2 evolution and the main acceleration of the reaction. The crystalline Ni-ME on g-C 3 N 4 was converted into an amorphous phase, which was a more stable and active Ni complex for the photocatalytic reaction. Ni-ME/g-C 3 N 4 is easy to prepare and is economically effective for solar hydrogen evolution.
Chemical Physics Letters, 2017
K-Al-based mixed oxides (KAl 6 O 9.5) with mullite structures were synthesized as CO 2 adsorption... more K-Al-based mixed oxides (KAl 6 O 9.5) with mullite structures were synthesized as CO 2 adsorption materials using a polymerized complex method. Al 3+ sites in the octahedral AlO 6 units of K-Al-based mixed oxides were substituted with various metal ions with +2 or +3 valence states to enhance basicity. Among these samples, the Fe-introduced sample (KAl 5.5 Fe 0.5 O 9.5) showed 130 times higher CO 2 adsorption capacity than that of Li 4 SiO 4. Raman spectra of these samples indicated that large distortions of the AlO 6 unit were observed only for the Fe-introduced sample. Local polarization caused by such distortions could induce increased basicity of this sample.
ChemSusChem, 2014
Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be h... more Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be harnessed as an alternate fuel source, which paves the way to a clean-energy future. A photoelectrochemical (PEC) system with a Nb:SrTiO3 photoelectrode for oxygen evolution from an aqueous electrolyte and a Pt/C electrode for toluene (TL) hydrogenation to MCH was investigated under UV irradiation. A Nb:SrTiO3 single-crystal electrode and an ionomer/Pt/C membrane-electrode assembly (MEA) were used as the photoanode and cathode, respectively. A steady-state current density of 0.12 mA cm(-2) was observed for the two-electrode system without any bias voltage for >2 h, and a Faradaic efficiency of 97% was obtained for MCH production from TL. This is the first demonstration of the production of MCH from TL and water using only light energy. This means that light energy was converted directly into MCH from TL and water without any electricity. The PEC properties of the devices are discussed.
Superlattices and Microstructures, 2008
... [7] S. Barman and L. Philip, Environ. Sci. Technol. 40 (2006), p. 1035. Full Text via CrossRe... more ... [7] S. Barman and L. Philip, Environ. Sci. Technol. 40 (2006), p. 1035. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (14). [8] JS Dalton, PA Janes, NG Jones, JA Nicholson, KR Hallam and GC Allen, Environ. Pollut. 120 (2002), p. 415. ...
Photochem. Photobiol. Sci., 2011
We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is... more We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is based on spraying a sol containing titanium alkoxide, concentrated HCl, a suitable block-copolymer serving as a structure directing agent and a solvent, the viscosity of the spraying sol and the conditions of spraying being precisely adjusted in order to achieve uniform coverage of the surface. The thickness of the films can be readily controlled by varying the number of deposited layers, their porosity being homogeneous and their surface area and pore volume increasing practically linearly with the increasing number of deposited layers. The mesoporous films of TiO 2 are highly promising photocatalysts for the oxidation of NO at low concentrations and the removal of liquid layers deposited on their surface.
Langmuir, 2014
Nanometric thin films were prepared by dip-coating and inkjet printing ZnO nanosheets on glass pl... more Nanometric thin films were prepared by dip-coating and inkjet printing ZnO nanosheets on glass plates. The side-by-side alignment of the ZnO nanosheets on the substrate resulted in thin, transparent, oriented ZnO surfaces with the high-energy {001} facets exposed. The method of nanosheet deposition affected the film morphology; the dip-coated films were very smooth and nonporous, while the inkjet-printed films were rough and porous with the estimated void volume approximately 60−70% of the total film volume. The first-order rate constants for the photocatalytic degradation of 4-chlorophenol on the nanosheet-based films were approximately 2 times larger than those on nanocolumnar ZnO films or ZnO films prepared by the sol−gel technique. We attribute the high photocatalytic activity of the ZnO nanosheets to the fact that their {001} facets were predominantly exposed to the oxidized substrate. This surface arrangement and the simplicity of fabricating the ZnO nanosheet-based films make them promising for the construction of optical devices and dye-sensitized solar cells.
Journal of the American Chemical Society, 2010
Ultrasmall and highly soluble anatase nanoparticles were synthesized from TiCl 4 using tertbutyl ... more Ultrasmall and highly soluble anatase nanoparticles were synthesized from TiCl 4 using tertbutyl alcohol as a new reaction medium. This synthetic protocol widens the scope of nonaqueous sol-gel methods to TiO 2 nanoparticles of around 3 nm with excellent dispersibility in ethanol and tert-butanol. Microwave heating was found to enhance the crystallinity of the nanoparticles and to drastically shorten the reaction time to less than 1 h at temperatures as low as 50°C. The extremely small size of the nanoparticles and their dispersibility make it possible to use commercial Pluronic surfactants for evaporationinduced self-assembly of the nanoparticulate building blocks into periodic mesoporous structures. A solution of particles after synthesis can be directly used for preparation of mesoporous films without the need for particle separation. The mesoporous titania coatings fabricated using this one-pot procedure are crystalline and exhibit high surface areas of up to 300 m 2 /g. The advantages of the retention of the mesoporous order with extremely thin nanocrystalline walls were shown by electrochemical lithium insertion. The films made using microwave-treated nanoparticles showed supercapacitive behavior with high maximum capacitance due to quantitative lithiation with a 10-fold increase of charging rates compared to a standard reference electrode made from 20 nm anatase particles.
Journal of Photochemistry and Photobiology A: Chemistry, 2010
We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is... more We have developed a low-cost procedure for the deposition of mesoporous films of TiO 2 , which is easy to use and applicable for objects of various shape and size. This technique is based on spraying a sol containing titanium alkoxide, HCl, a suitable block-copolymer serving as a structure directing agent, and a solvent. Both the viscosity of the sol and the spraying conditions were precisely adjusted in order to achieve uniform coverage of the surface. The thickness of the films can be readily controlled by varying the number of deposited layers, their porosity being homogeneous and their surface area and pore volume increasing practically linearly with the increasing number of deposited layers. The mesoporous films of TiO 2 are suitable photocatalysts for the oxidation of NO and the removal of liquid layers deposited on their surface. The effect of the flow rate of the gaseous mixture through the reactor on the photocatalytic conversion of NO was analyzed.
Journal of Hazardous Materials, 2012
A series of mesoporous films of titania of different thicknesses are prepared and their surface a... more A series of mesoporous films of titania of different thicknesses are prepared and their surface areas and porosities determined by physical adsorption using Kr as the adsorbate. The amounts of acid orange 7 (AO7) adsorbed by these films are found to be proportional to their measured surface areas and so the possibility of using this as a method of determining the surface area of thin titania films is discussed. The initial rates of UV-driven photocatalytic-and visible-driven photosensitised-bleaching of AO7 in solution, upon UVA and visible light irradiation, respectively, are also directly dependent upon the measured surface areas of the titania films. The quantum efficiencies for the UV photocatalytic-and visible photosensitised-bleaching of AO7 by the thickest of the AO7 films were estimated to be 0.08 and 0.01%, respectively.
Chemistry of Materials, 2009
Titania-silica composite films with a high content of crystalline titania phase and periodic meso... more Titania-silica composite films with a high content of crystalline titania phase and periodic mesoporous structure were fabricated by a low temperature "brick and mortar" approach. Pre-formed titania nanocrystals were fused with surfactant-templated sol-gel silica, which acts as a structure-directing matrix and as a chemical glue. The nature of the surfactant plays the decisive role in the mesostructure formation. Using Pluronic P123 as the structure-directing agent, the structure formation of the mesoporous silica is greatly disturbed as a result of the presence of titania nanoparticles. On the contrary, the use of Pluronic F127, whose molecules are larger and whose poly(ethylene oxide) blocks are more hydrophilic, enables the preparation of composite titania-silica mesoporous architectures that can accommodate up to 50 wt % of nanocrystals and yet retain the periodicity of the porous structure. In this way, films with a high degree of crystallinity were obtained at temperatures as low as 100-150°C and employed as active layers for the photooxidation of NO. The surface of the titania particles is not deactivated with respect to their photocatalytic activity by the surrounding silica matrix or by covalently attached ligands. The "brick and mortar" approach results in periodic mesoporous nanocomposites with photocatalytically active sites leading to functional coatings that are processed at low temperatures and thus opens new perspectives for their applicability on a wide range of substrates.
Chemistry of Materials, 2009
We present a novel "brick and mortar" strategy for creating highly efficient transparent TiO 2 co... more We present a novel "brick and mortar" strategy for creating highly efficient transparent TiO 2 coatings for photocatalytic and photovoltaic applications. Our approach is based on the fusion of preformed titania nanocrystalline "bricks" through surfactant-templated sol-gel titania "mortar", which acts as a structuredirecting matrix and as a chemical glue. The similar chemical composition of both bricks and mortar leads to a striking synergy in the interaction of crystalline and amorphous components, such that crystallization is enhanced upon thermal treatment and highly porous and highly crystalline structures are formed at very mild conditions. Coatings with a broad variety of periodic mesostructures and thicknesses ranging from few nanometers to several micrometers are accessible using the same organic template, and the final structures are tunable by varying the fraction of the "bricks". The beneficial combination of crystallinity and porosity leads to greatly enhanced activity of the films in photocatalytic processes, such as the photooxidation of NO. Acting as the active layers in dye-sensitized solar cells, films of only 2.7 µm in thickness exhibit a conversion efficiency of 6.0%.
Catalysis Today, 2014
Anatase TiO 2 coatings were grown on electrospun polymeric nanofibers (polyamide 6, polystyrene, ... more Anatase TiO 2 coatings were grown on electrospun polymeric nanofibers (polyamide 6, polystyrene, and polyurethane) via heterogeneous nucleation in an acidic aqueous solution of titanium oxysulfate at 60 • C. X-ray diffraction patterns confirmed a nanocrystalline anatase structure, and scanning electron microscopy observations revealed continuous coverage of the nanofiber surfaces by TiO 2. The morphology of the TiO 2 coatings was affected by the nature of the polymer. In all cases, the coatings generated hydroxyl radicals when irradiated with ultraviolet radiation. The materials were used for the photocatalytic oxidative removal of gaseous NO from air under irradiation at 365 nm. The functionalized polyamide 6 and polystyrene nanofibers were the most effective materials for converting NO to NO 2 and HNO 3. Based on our results, the anatase-coated nanofibers are promising materials for the removal of NO x pollutants from air.