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Papers by Joanna Kuncewicz

Research paper thumbnail of Correction: Rhodium-doped titania photocatalysts with two-step bandgap excitation by visible light—influence of the dopant concentration on photosensitization efficiency

RSC Advances, 2016

Correction for ‘Rhodium-doped titania photocatalysts with two-step bandgap excitation by visible ... more Correction for ‘Rhodium-doped titania photocatalysts with two-step bandgap excitation by visible light—influence of the dopant concentration on photosensitization efficiency’ by J. Kuncewicz and B. Ohtani, RSC Adv., 2016, 6, 77201–77211.

Research paper thumbnail of Sensitization of TiO2 by halogenated porphyrin derivatives for visible light biomedical and environmental photocatalysis

Catalysis Today, 2019

Abstract New hybrid TiO2-based materials were obtained by impregnation of semiconductor with 5,10... more Abstract New hybrid TiO2-based materials were obtained by impregnation of semiconductor with 5,10,15,20-tetrakis(2,6-difluorosulfonylophenyl)porphyrin (F2POH) and its zinc(II) complex (ZnF2POH). The efficient immobilization of the porphyrins on the surface of titanium dioxide was obtained due to the presence of -SO3H functional groups, which interact with the surface of TiO2. All prepared materials were thoroughly characterized in terms of their morphological, spectroscopic, electrochemical, photochemical and functional properties by diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, photoelectrochemistry as well as biological and photocatalytic tests. The modification of TiO2 with halogenated (metallo)porphyrins allows to improve overall properties of the studied materials and assess their activity upon visible part of the electromagnetic radiation (>400 nm). Nevertheless, due to their limited stability, observed photochemical effects are quite short lived. It is shown that the fluorine atoms present in porphyrin structure modulate not only physicochemical properties of the hybrid materials but also their photoactivity in the generation of reactive oxygen species (ROS). The materials based on fluorinated porphyrins have shown photocatalytic activity in the degradation of model pollutants: 4-chlorophenol and opioid drug – tramadol. Moreover, they exhibit quite significant antibacterial activity against Gram-positive (S. aureus), notably higher than TiO2 modified with commercial tetraphenyl porphyrin (TPPS). The role of singlet oxygen, hydroxyl and iodide radicals in the performed photoinactivation processes is elucidated for all studied systems. Finally, TiO2 alone is not active against bacteria upon visible light irradiation, what implies that materials containing fluorinated and sulfonated porphyrins have improved photochemical activity and efficiency of the ROS generation. Thus, they are interesting materials especially for photodynamic inactivation of microorganisms.

Research paper thumbnail of Mechanism of the photocatalytic processes on titanium(IV)-catecholate complexes upon two colors irradiation

Research paper thumbnail of Titania photocatalysis through two-photon band-gap excitation with built-in rhodium redox mediator

Chemical communications (Cambridge, England), Jan 7, 2015

Titania particles modified with an extremely small amount (<0.01 mol%) of a rhodium species ex... more Titania particles modified with an extremely small amount (<0.01 mol%) of a rhodium species exhibited photocatalytic activity for the oxidative decomposition of acetaldehyde in air under visible-light irradiation. The reaction proceeded via a two-photon band-gap excitation mechanism resembling the Z-scheme with an external redox couple, using a built-in Rh(iii)-Rh(iv) redox couple.

Research paper thumbnail of Titanium(IV) complexes as direct TiO2 photosensitizers

Coordination Chemistry Reviews, 2010

Research paper thumbnail of Photocatalysis Involving a Visible Light-Induced Hole Injection in a Chromate(VI)–TiO 2 System

The Journal of Physical Chemistry C, 2012

The photocatalytic activity of materials synthesized by titanium dioxide impregnation with chroma... more The photocatalytic activity of materials synthesized by titanium dioxide impregnation with chromates(VI) was studied in the processes of 4-chlorophenol oxidation and photocurrent generation. The materials show measurable activity when excited with visible light. Electron paramagnetic resonance (EPR) studies revealed the presence of chromium(V) species even without irradiation. Detection of photogenerated reactive oxygen species, together with elucidation of electrochemical properties of the materials, enabled assumption of a very unique mechanism of TiO 2 photosensitization, involving a photoinduced hole injection from the excited photosensitizer species to the valence band. Photoelectrochemical studies revealed that visible light induced both hole injection to the valence band and electron injection to the conduction band, depending on the electrode potential. The former process is responsible for anodic, whereas the latter is responsible for cathodic photocurrent generation. This counterintuitive behavior results from a peculiar arrangement of electronic levels in the studied systems. Although the (photo)stability of studied materials, as well as the efficiency of the photosensitization process are moderate, the system represents a very unique and therefore interesting mode of titania photosensitization.

Research paper thumbnail of Visible light driven photocatalysis in chromate(VI)/TiO2 systems—Improving stability of the photocatalyst

Catalysis Today, 2011

Titanium dioxide photosensitization to visible light can be observed in the presence of chromate(... more Titanium dioxide photosensitization to visible light can be observed in the presence of chromate(VI) ions adsorbed at the surface of TiO2. The resulting materials do not show, however, sufficient stability and photostability—chromium(VI) species desorb from the surface and can be reduced to chromium(III). The stability of such systems has been improved by TiO2 impregnation with fluorochromate(VI), K[CrO3F], instead of K2Cr2O7, yielding yellow F-CrVI@TiO2 material. Fluorides playing the role of anchors enable stronger adsorption of chromates at titanium dioxide. Also composites of water insoluble chromates(VI) with TiO2 release significantly lower amounts of CrVI ions. Such materials have been synthesized according to two main strategies—the first one involves precipitation of water insoluble chromates in the presence of TiO2 particles (MCrO4@TiO2) while the second strategy comprises of TiO2 synthesis in the presence of insoluble chromate particles (TiO2@MCrO4). Visible light induced photocatalytic activity of synthesized materials was studied in the process of 4-chlorophenol (4-CP) oxidation. A considerable photocatalytic activity was observed in the case of F-CrVI@TiO2 and TiO2@MCrO4 type materials (Mn+: Ba2+, Co2+, Mn2+, Cr3+). Among the composites the highest photoreactivity was shown by TiO2@CoCrO4 (1.7% CrVI, mol/mol, calcined at 450°C) and TiO2@Cr2(CrO4)3 (5% CrVI, mol/mol, calcined at 450°C).

Research paper thumbnail of Photoinduced hole injection in semiconductor-coordination compound systems

Coordination Chemistry Reviews, 2013

Research paper thumbnail of Correction: Rhodium-doped titania photocatalysts with two-step bandgap excitation by visible light—influence of the dopant concentration on photosensitization efficiency

RSC Advances, 2016

Correction for ‘Rhodium-doped titania photocatalysts with two-step bandgap excitation by visible ... more Correction for ‘Rhodium-doped titania photocatalysts with two-step bandgap excitation by visible light—influence of the dopant concentration on photosensitization efficiency’ by J. Kuncewicz and B. Ohtani, RSC Adv., 2016, 6, 77201–77211.

Research paper thumbnail of Sensitization of TiO2 by halogenated porphyrin derivatives for visible light biomedical and environmental photocatalysis

Catalysis Today, 2019

Abstract New hybrid TiO2-based materials were obtained by impregnation of semiconductor with 5,10... more Abstract New hybrid TiO2-based materials were obtained by impregnation of semiconductor with 5,10,15,20-tetrakis(2,6-difluorosulfonylophenyl)porphyrin (F2POH) and its zinc(II) complex (ZnF2POH). The efficient immobilization of the porphyrins on the surface of titanium dioxide was obtained due to the presence of -SO3H functional groups, which interact with the surface of TiO2. All prepared materials were thoroughly characterized in terms of their morphological, spectroscopic, electrochemical, photochemical and functional properties by diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, photoelectrochemistry as well as biological and photocatalytic tests. The modification of TiO2 with halogenated (metallo)porphyrins allows to improve overall properties of the studied materials and assess their activity upon visible part of the electromagnetic radiation (>400 nm). Nevertheless, due to their limited stability, observed photochemical effects are quite short lived. It is shown that the fluorine atoms present in porphyrin structure modulate not only physicochemical properties of the hybrid materials but also their photoactivity in the generation of reactive oxygen species (ROS). The materials based on fluorinated porphyrins have shown photocatalytic activity in the degradation of model pollutants: 4-chlorophenol and opioid drug – tramadol. Moreover, they exhibit quite significant antibacterial activity against Gram-positive (S. aureus), notably higher than TiO2 modified with commercial tetraphenyl porphyrin (TPPS). The role of singlet oxygen, hydroxyl and iodide radicals in the performed photoinactivation processes is elucidated for all studied systems. Finally, TiO2 alone is not active against bacteria upon visible light irradiation, what implies that materials containing fluorinated and sulfonated porphyrins have improved photochemical activity and efficiency of the ROS generation. Thus, they are interesting materials especially for photodynamic inactivation of microorganisms.

Research paper thumbnail of Mechanism of the photocatalytic processes on titanium(IV)-catecholate complexes upon two colors irradiation

Research paper thumbnail of Titania photocatalysis through two-photon band-gap excitation with built-in rhodium redox mediator

Chemical communications (Cambridge, England), Jan 7, 2015

Titania particles modified with an extremely small amount (<0.01 mol%) of a rhodium species ex... more Titania particles modified with an extremely small amount (<0.01 mol%) of a rhodium species exhibited photocatalytic activity for the oxidative decomposition of acetaldehyde in air under visible-light irradiation. The reaction proceeded via a two-photon band-gap excitation mechanism resembling the Z-scheme with an external redox couple, using a built-in Rh(iii)-Rh(iv) redox couple.

Research paper thumbnail of Titanium(IV) complexes as direct TiO2 photosensitizers

Coordination Chemistry Reviews, 2010

Research paper thumbnail of Photocatalysis Involving a Visible Light-Induced Hole Injection in a Chromate(VI)–TiO 2 System

The Journal of Physical Chemistry C, 2012

The photocatalytic activity of materials synthesized by titanium dioxide impregnation with chroma... more The photocatalytic activity of materials synthesized by titanium dioxide impregnation with chromates(VI) was studied in the processes of 4-chlorophenol oxidation and photocurrent generation. The materials show measurable activity when excited with visible light. Electron paramagnetic resonance (EPR) studies revealed the presence of chromium(V) species even without irradiation. Detection of photogenerated reactive oxygen species, together with elucidation of electrochemical properties of the materials, enabled assumption of a very unique mechanism of TiO 2 photosensitization, involving a photoinduced hole injection from the excited photosensitizer species to the valence band. Photoelectrochemical studies revealed that visible light induced both hole injection to the valence band and electron injection to the conduction band, depending on the electrode potential. The former process is responsible for anodic, whereas the latter is responsible for cathodic photocurrent generation. This counterintuitive behavior results from a peculiar arrangement of electronic levels in the studied systems. Although the (photo)stability of studied materials, as well as the efficiency of the photosensitization process are moderate, the system represents a very unique and therefore interesting mode of titania photosensitization.

Research paper thumbnail of Visible light driven photocatalysis in chromate(VI)/TiO2 systems—Improving stability of the photocatalyst

Catalysis Today, 2011

Titanium dioxide photosensitization to visible light can be observed in the presence of chromate(... more Titanium dioxide photosensitization to visible light can be observed in the presence of chromate(VI) ions adsorbed at the surface of TiO2. The resulting materials do not show, however, sufficient stability and photostability—chromium(VI) species desorb from the surface and can be reduced to chromium(III). The stability of such systems has been improved by TiO2 impregnation with fluorochromate(VI), K[CrO3F], instead of K2Cr2O7, yielding yellow F-CrVI@TiO2 material. Fluorides playing the role of anchors enable stronger adsorption of chromates at titanium dioxide. Also composites of water insoluble chromates(VI) with TiO2 release significantly lower amounts of CrVI ions. Such materials have been synthesized according to two main strategies—the first one involves precipitation of water insoluble chromates in the presence of TiO2 particles (MCrO4@TiO2) while the second strategy comprises of TiO2 synthesis in the presence of insoluble chromate particles (TiO2@MCrO4). Visible light induced photocatalytic activity of synthesized materials was studied in the process of 4-chlorophenol (4-CP) oxidation. A considerable photocatalytic activity was observed in the case of F-CrVI@TiO2 and TiO2@MCrO4 type materials (Mn+: Ba2+, Co2+, Mn2+, Cr3+). Among the composites the highest photoreactivity was shown by TiO2@CoCrO4 (1.7% CrVI, mol/mol, calcined at 450°C) and TiO2@Cr2(CrO4)3 (5% CrVI, mol/mol, calcined at 450°C).

Research paper thumbnail of Photoinduced hole injection in semiconductor-coordination compound systems

Coordination Chemistry Reviews, 2013