Marta Buchalska - Academia.edu (original) (raw)

Papers by Marta Buchalska

Applied Catalysis B: Environmental

Abstract The goal of the work is to verify which properties of TiO2-based materials, influenced b... more Abstract The goal of the work is to verify which properties of TiO2-based materials, influenced by small amounts of Fe, Co, Ga, Bi, W, Mo, V and Ni species used as modifiers, play the predominant role in changing the photoactivity of TiO2. Two groups of materials were studied: TiO2 synthesized in the presence of nanocrystalline metal oxide and dissolved metal ions (cations or oxyanions). Sols were calcined at 450, 600 or 900°C. Physicochemical properties of the materials were characterized by XRD, DRS, SEM, EPR, porosimetry and photocurrent measurements. The most detailed studies were focused on modifications by iron species. TiO2 doping was achieved for both Fe3+ and Fe2O3 modifiers after calcination at temperatures equal to or higher than 450 and 900°C, respectively. Morphology of the materials (phase composition, specific surface area, etc.) were influenced by iron species even if they were not introduced into the crystal lattice of TiO2. Comparison of activity of photocatalysts and elucidation of the role of various reactive oxygen species were based on photooxidation tests involving Azure B and terephthalic acid. In general, iron species improved photocatalytic activity, nevertheless, doping of the materials appeared detrimental. A particular improvement of the activity was achieved for composites with low iron contents (ca. 0.01%mol Fe:Ti). The studies revealed, that beside the widely discussed mechanisms (photo-Fenton processes, charge separation, photosensitization, etc.) iron species can indirectly influence the photocatalytic activity of TiO2 acting as phase-composition controllers (PCC) during the synthesis of this oxide, which determine morphology of the resulting photocatalyst. To support this hypothesis, several sets of other TiO2 materials were modified with Co, Ga, Bi, W, Mo, V and Ni species. We show, that the use of these modifiers in small amounts can influence indirectly the activity of photocatalysts regardless to the type of modifier. Therefore different photoactivity of the tested materials should be attributed to these modifier-induced structural and electronic changes of the photocatalysts rather than to any other function of dopants, including photosensitization, enhanced charge separation, catalytic activity, at which most of studies are focused.

Applied Surface Science

Abstract Photocatalytic coatings at polymers, showing a visible light induced photoactivity, can ... more Abstract Photocatalytic coatings at polymers, showing a visible light induced photoactivity, can be synthesized using a low temperature oxygen plasma treatment of the polymer (PP) followed by deposition of TiO2 nanoparticles and their sensitization with organic ligands. The whole process consists of three major steps: surface activation involving its partial oxidation, immobilization of TiO2 nanoparticles and photosensitization of titania film by impregnation with the solution of organic ligands forming surface Ti(IV) charge transfer complexes. XPS and IR analysis revealed the formation of oxygen-containing groups at the polymer surface upon plasma treatment. These groups participate in the formation of Ti O C bonds which ensure a very good adhesion of titania films to polymeric surface. The dip-coating process using an aqueous colloidal solution of TiO2 nanoparticles allows to synthesize a compact coating with a thickness of 100–300 nm. Coordination of catechol-like ligands to surface Ti(IV) centers results in formation of colored charge transfer complexes responsible for absorption of visible light and an effective photoinduced charge separation. Photogenerated electrons and holes can take part in surface redox reactions responsible for degradation of pollutants. Tests with various organic ligands (catechol, 2,3-naphthalenediol, pyrogallol and rutin) revealed, that the titanium dioxide coating modified with catechol was the most photoactive one when visible light irradiation was applied. Presented photocatalytic coatings can be effectively used as self-sterilizing surfaces activated by visible light.

The Journal of Physical Chemistry C, 2016

Utilization of visible light by photosensitization of semiconductor photocatalysts via surface at... more Utilization of visible light by photosensitization of semiconductor photocatalysts via surface attachment of small colorless organic pollutants (COP) is an effective way to stimulate their photocatalytic degradation. Herein, by means of the spectroscopic, photoelectrochemical, spectroelectrochemical, and photocatalytic studies combined with the DFT+D molecular modeling, we show how disubstituted benzene derivatives, like catechol (CAT), salicylic acid (SAL), phthalic acid (PTA), and terephthalic acid (TPA), can tune the photocatalytic properties of rutile nanorods with the dominant (110) termination. We elucidated in a systematic way the COP ligand-binding configurations, the alignment of energy levels, and the charge-transfer pathways from the organic admolecules to the titania substrate. The pDOS structures of the COP@r-TiO2(110) assemblies were interpreted in terms of electronic interactions between the titania photocatalyst and the COP adspecies. It was shown that the appearance of additional states w...

Archiwum Uj Dokt 2012 192, 2012

Catalysis Today, Nov 11, 2014

Abstract TiO2 films were deposited on the native oxide covered Si(1 0 0) with ALD method. The fil... more Abstract TiO2 films were deposited on the native oxide covered Si(1 0 0) with ALD method. The films were grown applying various numbers of deposition cycles at different temperatures. The resulting coatings possessed different thickness, crystallinity, morphology and roughness. The photocatalytic activity of the films has been studied in the presence of terephthalic acid, Azur B and two herbicides: 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Coatings deposited at 350 °C (anatase–rutile composites) show the highest activity in the process of TA oxidation (the highest efficiency of hydroxyl radical generation). The influence of film thickness on photoactivity is more complex and depends on the mechanism of processes to be photocatalysed.

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 4, 2015

Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and... more Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and covered with a thin film of nanocrystalline titanium dioxide by dip coating. The films were then photosensitized by titanium(iv) surface charge transfer complexes formed by impregnation with catechol. The photoactivity of the coatings up to 460 nm was confirmed by photoelectrochemical measurements. The photoinactivation of Escherichia coli and Staphylococcus aureus was evaluated by a glass adhesion test based on ISO 27447:2009(E) in the presence of visible light. The coating showed good antimicrobial activity induced by light from a light-emitting diode (405 nm), in particular towards E. coli ATCC 25922 strain. Adaptation of ISO 27447:2009(E) to assess bacterial photoinactivation by photocatalytic coatings will allow this procedure to be applied for the comparison of photoactivity under a range of irradiation conditions.

ACS Catalysis, 2015

The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than t... more The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than that of anatase-TiO2 (a-TiO2). Nevertheless, there are numerous examples of sometimes unexpectedly high activity of r-TiO2. This material may appear to be particularly useful when a noncomplete and selective photocatalytic oxidation of organic substrates is required. On the basis of literature examples and our own studies, we compare the photocatalytic activities of r-TiO2, a-TiO2, and r-TiO2/a-TiO2 composites. Because of a significantly better oxygen adsorption at the surface of r-TiO2 and a lower redox potential of the excited electron, more efficient O2•– production takes place at the surface of rutile. As a consequence, generation of 1O2 (involving O2 reduction and the subsequent oxidation of superoxide) and reduction of H2O2 to OH– and HO• are also favored with this material. Therefore, r-TiO2 can be considered to be a particularly good photocatalyst for activation of molecular oxygen. On the other hand, a...

ACS Catalysis, 2015

The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than t... more The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than that of anatase-TiO2 (a-TiO2). Nevertheless, there are numerous examples of sometimes unexpectedly high activity of r-TiO2. This material may appear to be particularly useful when a noncomplete and selective photocatalytic oxidation of organic substrates is required. On the basis of literature examples and our own studies, we compare the photocatalytic activities of r-TiO2, a-TiO2, and r-TiO2/a-TiO2 composites. Because of a significantly better oxygen adsorption at the surface of r-TiO2 and a lower redox potential of the excited electron, more efficient O2•– production takes place at the surface of rutile. As a consequence, generation of 1O2 (involving O2 reduction and the subsequent oxidation of superoxide) and reduction of H2O2 to OH– and HO• are also favored with this material. Therefore, r-TiO2 can be considered to be a particularly good photocatalyst for activation of molecular oxygen. On the other hand, a-TiO2 appears to be a stronger oxidant. In its presence, efficient HO• generation (the result of water or surface hydroxyl group oxidation) and oxidation of H2O2 to O2•– are observed.

Coordination Chemistry Reviews, 2010

The Journal of Physical Chemistry C, 2014

A group of selected hexafluorometallates ([AlF6]3–, [TiF6]2–, [ZrF6]2–, [SiF6]2–) has been adsorb... more A group of selected hexafluorometallates ([AlF6]3–, [TiF6]2–, [ZrF6]2–, [SiF6]2–) has been adsorbed at titanium dioxide. Such modification influenced electronic and chemical properties of TiO2, as well as its photoactivity. The modification with [TiF6]2– inhibited the efficiency of OH• production, but enhanced generation of photocurrent and singlet oxygen. The results of modifications with [ZrF6]2– were opposite – generation of 1O2 was not observed in this case and photocurrents were lower, however, due to a better OH• production, degradation of herbicides was faster.

Coordination Chemistry Reviews, 2010

Coordination Chemistry Reviews, 2013

The goal of this study was to test photoreactivity of commercially available suntan lotions and t... more The goal of this study was to test photoreactivity of commercially available suntan lotions and their components (mainly TiO2). Isolated water insoluble components containing titanium dioxide appeared almost non-active in the tests of 4-chlorophenol degradation, however a fast UV-light induced degradation of azur B and oxidation of α-terpinene to ascaridol in the presence of these materials was observed. The photoreactivity of suntan lotions and their components was compared to the photoactivity of phenalenone (an efficient 1O2 photosensitizer). The results have proven a relatively low efficiency of hydroxyl radicals formation, however significant rates of reactions involving singlet oxygen were observed in the presence of either the components of the cosmetics or the suntan lotions used as received. Moreover, an efficient photocurrent generation by photoelectrodes made of isolated TiO2 materials reflects their photoredox properties. Although singlet oxygen scavengers used as additives in suntan lotions might decrease the risk related to generation of this reactive oxygen species, producers of cosmetics containing titanium dioxide should consider testing TiO2 photoactivity in reference to 1O2 generation.

Dalton Transactions, 2013

Applied Catalysis B: Environmental

Abstract The goal of the work is to verify which properties of TiO2-based materials, influenced b... more Abstract The goal of the work is to verify which properties of TiO2-based materials, influenced by small amounts of Fe, Co, Ga, Bi, W, Mo, V and Ni species used as modifiers, play the predominant role in changing the photoactivity of TiO2. Two groups of materials were studied: TiO2 synthesized in the presence of nanocrystalline metal oxide and dissolved metal ions (cations or oxyanions). Sols were calcined at 450, 600 or 900°C. Physicochemical properties of the materials were characterized by XRD, DRS, SEM, EPR, porosimetry and photocurrent measurements. The most detailed studies were focused on modifications by iron species. TiO2 doping was achieved for both Fe3+ and Fe2O3 modifiers after calcination at temperatures equal to or higher than 450 and 900°C, respectively. Morphology of the materials (phase composition, specific surface area, etc.) were influenced by iron species even if they were not introduced into the crystal lattice of TiO2. Comparison of activity of photocatalysts and elucidation of the role of various reactive oxygen species were based on photooxidation tests involving Azure B and terephthalic acid. In general, iron species improved photocatalytic activity, nevertheless, doping of the materials appeared detrimental. A particular improvement of the activity was achieved for composites with low iron contents (ca. 0.01%mol Fe:Ti). The studies revealed, that beside the widely discussed mechanisms (photo-Fenton processes, charge separation, photosensitization, etc.) iron species can indirectly influence the photocatalytic activity of TiO2 acting as phase-composition controllers (PCC) during the synthesis of this oxide, which determine morphology of the resulting photocatalyst. To support this hypothesis, several sets of other TiO2 materials were modified with Co, Ga, Bi, W, Mo, V and Ni species. We show, that the use of these modifiers in small amounts can influence indirectly the activity of photocatalysts regardless to the type of modifier. Therefore different photoactivity of the tested materials should be attributed to these modifier-induced structural and electronic changes of the photocatalysts rather than to any other function of dopants, including photosensitization, enhanced charge separation, catalytic activity, at which most of studies are focused.

Applied Surface Science

Abstract Photocatalytic coatings at polymers, showing a visible light induced photoactivity, can ... more Abstract Photocatalytic coatings at polymers, showing a visible light induced photoactivity, can be synthesized using a low temperature oxygen plasma treatment of the polymer (PP) followed by deposition of TiO2 nanoparticles and their sensitization with organic ligands. The whole process consists of three major steps: surface activation involving its partial oxidation, immobilization of TiO2 nanoparticles and photosensitization of titania film by impregnation with the solution of organic ligands forming surface Ti(IV) charge transfer complexes. XPS and IR analysis revealed the formation of oxygen-containing groups at the polymer surface upon plasma treatment. These groups participate in the formation of Ti O C bonds which ensure a very good adhesion of titania films to polymeric surface. The dip-coating process using an aqueous colloidal solution of TiO2 nanoparticles allows to synthesize a compact coating with a thickness of 100–300 nm. Coordination of catechol-like ligands to surface Ti(IV) centers results in formation of colored charge transfer complexes responsible for absorption of visible light and an effective photoinduced charge separation. Photogenerated electrons and holes can take part in surface redox reactions responsible for degradation of pollutants. Tests with various organic ligands (catechol, 2,3-naphthalenediol, pyrogallol and rutin) revealed, that the titanium dioxide coating modified with catechol was the most photoactive one when visible light irradiation was applied. Presented photocatalytic coatings can be effectively used as self-sterilizing surfaces activated by visible light.

The Journal of Physical Chemistry C, 2016

Utilization of visible light by photosensitization of semiconductor photocatalysts via surface at... more Utilization of visible light by photosensitization of semiconductor photocatalysts via surface attachment of small colorless organic pollutants (COP) is an effective way to stimulate their photocatalytic degradation. Herein, by means of the spectroscopic, photoelectrochemical, spectroelectrochemical, and photocatalytic studies combined with the DFT+D molecular modeling, we show how disubstituted benzene derivatives, like catechol (CAT), salicylic acid (SAL), phthalic acid (PTA), and terephthalic acid (TPA), can tune the photocatalytic properties of rutile nanorods with the dominant (110) termination. We elucidated in a systematic way the COP ligand-binding configurations, the alignment of energy levels, and the charge-transfer pathways from the organic admolecules to the titania substrate. The pDOS structures of the COP@r-TiO2(110) assemblies were interpreted in terms of electronic interactions between the titania photocatalyst and the COP adspecies. It was shown that the appearance of additional states w...

Archiwum Uj Dokt 2012 192, 2012

Catalysis Today, Nov 11, 2014

Abstract TiO2 films were deposited on the native oxide covered Si(1 0 0) with ALD method. The fil... more Abstract TiO2 films were deposited on the native oxide covered Si(1 0 0) with ALD method. The films were grown applying various numbers of deposition cycles at different temperatures. The resulting coatings possessed different thickness, crystallinity, morphology and roughness. The photocatalytic activity of the films has been studied in the presence of terephthalic acid, Azur B and two herbicides: 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Coatings deposited at 350 °C (anatase–rutile composites) show the highest activity in the process of TA oxidation (the highest efficiency of hydroxyl radical generation). The influence of film thickness on photoactivity is more complex and depends on the mechanism of processes to be photocatalysed.

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, Jan 4, 2015

Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and... more Commercially available polypropylene foil was pretreated with a low temperature oxygen plasma and covered with a thin film of nanocrystalline titanium dioxide by dip coating. The films were then photosensitized by titanium(iv) surface charge transfer complexes formed by impregnation with catechol. The photoactivity of the coatings up to 460 nm was confirmed by photoelectrochemical measurements. The photoinactivation of Escherichia coli and Staphylococcus aureus was evaluated by a glass adhesion test based on ISO 27447:2009(E) in the presence of visible light. The coating showed good antimicrobial activity induced by light from a light-emitting diode (405 nm), in particular towards E. coli ATCC 25922 strain. Adaptation of ISO 27447:2009(E) to assess bacterial photoinactivation by photocatalytic coatings will allow this procedure to be applied for the comparison of photoactivity under a range of irradiation conditions.

ACS Catalysis, 2015

The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than t... more The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than that of anatase-TiO2 (a-TiO2). Nevertheless, there are numerous examples of sometimes unexpectedly high activity of r-TiO2. This material may appear to be particularly useful when a noncomplete and selective photocatalytic oxidation of organic substrates is required. On the basis of literature examples and our own studies, we compare the photocatalytic activities of r-TiO2, a-TiO2, and r-TiO2/a-TiO2 composites. Because of a significantly better oxygen adsorption at the surface of r-TiO2 and a lower redox potential of the excited electron, more efficient O2•– production takes place at the surface of rutile. As a consequence, generation of 1O2 (involving O2 reduction and the subsequent oxidation of superoxide) and reduction of H2O2 to OH– and HO• are also favored with this material. Therefore, r-TiO2 can be considered to be a particularly good photocatalyst for activation of molecular oxygen. On the other hand, a...

ACS Catalysis, 2015

The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than t... more The rutile form of titanium dioxide (r-TiO2) usually shows a photocatalytic activity lower than that of anatase-TiO2 (a-TiO2). Nevertheless, there are numerous examples of sometimes unexpectedly high activity of r-TiO2. This material may appear to be particularly useful when a noncomplete and selective photocatalytic oxidation of organic substrates is required. On the basis of literature examples and our own studies, we compare the photocatalytic activities of r-TiO2, a-TiO2, and r-TiO2/a-TiO2 composites. Because of a significantly better oxygen adsorption at the surface of r-TiO2 and a lower redox potential of the excited electron, more efficient O2•– production takes place at the surface of rutile. As a consequence, generation of 1O2 (involving O2 reduction and the subsequent oxidation of superoxide) and reduction of H2O2 to OH– and HO• are also favored with this material. Therefore, r-TiO2 can be considered to be a particularly good photocatalyst for activation of molecular oxygen. On the other hand, a-TiO2 appears to be a stronger oxidant. In its presence, efficient HO• generation (the result of water or surface hydroxyl group oxidation) and oxidation of H2O2 to O2•– are observed.

Coordination Chemistry Reviews, 2010

The Journal of Physical Chemistry C, 2014

A group of selected hexafluorometallates ([AlF6]3–, [TiF6]2–, [ZrF6]2–, [SiF6]2–) has been adsorb... more A group of selected hexafluorometallates ([AlF6]3–, [TiF6]2–, [ZrF6]2–, [SiF6]2–) has been adsorbed at titanium dioxide. Such modification influenced electronic and chemical properties of TiO2, as well as its photoactivity. The modification with [TiF6]2– inhibited the efficiency of OH• production, but enhanced generation of photocurrent and singlet oxygen. The results of modifications with [ZrF6]2– were opposite – generation of 1O2 was not observed in this case and photocurrents were lower, however, due to a better OH• production, degradation of herbicides was faster.

Coordination Chemistry Reviews, 2010

Coordination Chemistry Reviews, 2013

The goal of this study was to test photoreactivity of commercially available suntan lotions and t... more The goal of this study was to test photoreactivity of commercially available suntan lotions and their components (mainly TiO2). Isolated water insoluble components containing titanium dioxide appeared almost non-active in the tests of 4-chlorophenol degradation, however a fast UV-light induced degradation of azur B and oxidation of α-terpinene to ascaridol in the presence of these materials was observed. The photoreactivity of suntan lotions and their components was compared to the photoactivity of phenalenone (an efficient 1O2 photosensitizer). The results have proven a relatively low efficiency of hydroxyl radicals formation, however significant rates of reactions involving singlet oxygen were observed in the presence of either the components of the cosmetics or the suntan lotions used as received. Moreover, an efficient photocurrent generation by photoelectrodes made of isolated TiO2 materials reflects their photoredox properties. Although singlet oxygen scavengers used as additives in suntan lotions might decrease the risk related to generation of this reactive oxygen species, producers of cosmetics containing titanium dioxide should consider testing TiO2 photoactivity in reference to 1O2 generation.

Dalton Transactions, 2013