Fabrication by AC Deposition and Antimicrobial Properties of Pyramidal-Shaped Cu2O-TiO2 Heterostructures

Nanoparticulate surfaces possessing antimicrobial and fungicidal properties under visible light illumination have found wide applications in a number of fields. In this study, titania nanotubes, as well as titania compact films were designed with pure Cu2O crystals in a mildly acidic copper acetate solution using a simple alternating current (AC) deposition approach. In this way, the thermally oxidized Ti substrate was coated by densely packed pyramidal and bipyramidal shaped Cu2O crystals with dominant (111) planes and investigated against several types of fungi and bacteria. For comparison, TiO2 nanotube (TiNT) films were also decorated with similar crystals and tested. The results showed that, compared to bare TiO2 films, both Cu2O-in-TiNT and Cu2O-on-TiO2 heterostructures exhibited remarkably enhanced activity against tested fungi and bacteria. We also demonstrated that the high photoactivity of these crystals remained even after 50 h stability tests under bright light illumination. The results obtained from in vitro tests indicated that Cu2O-in/on-TiO2 heterostructures show promise as visible light driven antimicrobial materials

Study on titanium anodic films decoration with visible light absorbing semiconductor nanostructures

New nanostructure materials, their order colonies, layered films, synthesis and construction of heterostructures allow scientists to develop at those days new or improved properties of materials that will determine the future of scientific and technological progress. The thesis is related to prospective studies of nanostructured TiO2 layers and film composites with other semiconductor nanoparticles based on their environmental friendliness, low cost, chemical and mechanical resistance. The aim of the work was the investigate the possibilities of anodic TiO2 film nanotubes for electrochemical decoration of lower band gap semiconductor nanoparticles. The methods for uniform decoration of anatase TiO2 nanotube (Ntb) films with Cu2O nanoparticles were proposed: with weakly acidic copper acetate electrolyte and alternating current. Growth of pure Cu2O crystals in the TiO2 Ntbs was based on thermodynamic analysis of the solution. It has been discovered that TiO2 Ntb films decorated with Cu2O nanoparticles are able to absorb not only the UV light, but visible light as well. By increasing amount of Cu2O deposited in the TiO2 nanotubes, the TiO2 Ntb – Cu2O absorption edge can be moved up to 2.1 eV. The possibility of electrochemical decoration of TiO2 Ntb film with semiconducting copper selenide nanoparticles in aqueous solutions and the peculiarities of the process were investigated. The effect of hydrogen doping of the Ti/TiO2 Ntb electrode for uniform decoration of TiO2 nanotubes with semiconducting nanoparticles was used for the first time. It was determined that TiO2 Ntb – Cu2O heterostructures are characterised by significantly lower dependence on the angle of incidence of excitation beam – this can be especially useful for solar cell circuits. Investigated optical properties and light absorption features of TiO2 Ntb decorated with copper selenide (Cu3Se2 and Cu2-xSe) nanoparticles. Optimized composition of hydrothermal processing solution and conditions for decoration of TiO2 Ntb film surfaces and nanotubes with nanoleafed MoS2. The uniform formation of crystalline MoS2 on the TiO2 surface is achieved with low concentration ammonium heptamolybdate and urea solutions within the temperature of 220 to 225 °C. It was determined that Ti/TiO2 Ntb – MoS2 electrodes catalyse hydrogen release from acidic solutions and the reaction is characterized by stability

Titano anodinių plėvelių dekoravimo matomą šviesą sugeriančiais puslaidininkių nanodariniais tyrimas

New nanostructure materials, their order colonies, layered films, synthesis and construction of heterostructures allow scientists to develop at those days new or improved properties of materials that will determine the future of scientific and technological progress. The thesis is related to prospective studies of nanostructured TiO2 layers and film composites with other semiconductor nanoparticles based on their environmental friendliness, low cost, chemical and mechanical resistance. The aim of the work was the investigate the possibilities of anodic TiO2 film nanotubes for electrochemical decoration of lower band gap semiconductor nanoparticles. The methods for uniform decoration of anatase TiO2 nanotube (Ntb) films with Cu2O nanoparticles were proposed: with weakly acidic copper acetate electrolyte and alternating current. Growth of pure Cu2O crystals in the TiO2 Ntbs was based on thermodynamic analysis of the solution. It has been discovered that TiO2 Ntb films decorated with Cu2O nanoparticles are able to absorb not only the UV light, but visible light as well. By increasing amount of Cu2O deposited in the TiO2 nanotubes, the TiO2 Ntb – Cu2O absorption edge can be moved up to 2.1 eV. The possibility of electrochemical decoration of TiO2 Ntb film with semiconducting copper selenide nanoparticles in aqueous solutions and the peculiarities of the process were investigated. The effect of hydrogen doping of the Ti/TiO2 Ntb electrode for uniform decoration of TiO2 nanotubes with semiconducting nanoparticles was used for the first time. It was determined that TiO2 Ntb – Cu2O heterostructures are characterised by significantly lower dependence on the angle of incidence of excitation beam – this can be especially useful for solar cell circuits. Investigated optical properties and light absorption features of TiO2 Ntb decorated with copper selenide (Cu3Se2 and Cu2-xSe) nanoparticles. Optimized composition of hydrothermal processing solution and conditions for decoration of TiO2 Ntb film surfaces and nanotubes with nanoleafed MoS2. The uniform formation of crystalline MoS2 on the TiO2 surface is achieved with low concentration ammonium heptamolybdate and urea solutions within the temperature of 220 to 225 °C. It was determined that Ti/TiO2 Ntb – MoS2 electrodes catalyse hydrogen release from acidic solutions and the reaction is characterized by stability

Research on Hydrothermal Decoration of TiO2 Nanotube Films with Nanoplatelet MoS2 Species

In this study, novel electrodes were prepared via decoration of nanotubed TiO2 (TiNT) films with crystalline two- dimensional (2D) MoS2 species by a one-step hydrothermal synthesis approach. Obtained products were characterized in detail by scanning electron microscopy, Raman spectro‐ scopy, U-I measurements and X-ray diffraction techniques. The influence of hydrothermal synthesis conditions on the composition and morphology of the products formed in the solution and within the TiNT film are also discussed. For the first time, acceptable decoration of TiNT films, by tethering 2D layered MoS2 leaflets onto the TiO2 nanotubes, and on the film surface was obtained in the low concentra‐ tion solutions, while the performance of these heterostruc‐ tures in relation to electrochemical hydrogen evolution reaction (HER) was tested. Stable catalytic activity of the obtained 2D MoS2-in-TiNT films was demonstrated under intense HER conditions within the potential window [-0.2 to - 0.4 V] vs. RHE with a notably low Tafel slope of 33 mV/ decade