Effect of TiO2 and ZnO powder mixtures on mechanical and photocatalytic performance of high performance concrete

The development of new modified cement-based materials is increasingly becoming a necessity for improving the durability and surface performance of building materials. Titanium dioxide (TiO2) photocatalyst has been widely used in building materials science due to its ability to break down pollutants. Zinc oxide (ZnO) is often considered a substituent for TiO2 because of its photocatalytic and photoluminescent properties. A new inorganic nanocomposite photocatalyst, based on titanium and zinc oxides, is introduced in this work in order to study its compatibility with High Performance Concrete (HPC). This research aims to study the mechanical and photocatalytic behavior of mixtures based on nanoparticles in HPC. The study of the efficiency in the nitrogen oxides (NOx) degradation of modified HPC in TiO2 and ZnO with different percentages is studied. The studies have shown that the introduction of titanium dioxide in HPC presents a significant efficiency for the NOx degradation and a positive effect on the mechanical properties than zinc oxide, and thus represents potential contribution to sustainability of concrete structures

Graphitic carbon nitride for photocatalytic air treatment

Graphitic carbon nitride (g-C3N4) is a conjugated polymer, which recently drew a lot of attention as a metal-free and UV and visible light responsive photocatalyst in the field of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability and earth-abundant nature. In the present work, bulk g-C(3)N(4)was synthesized by thermal decomposition of melamine. This material was further exfoliated by thermal treatment. S-doped samples were prepared from thiourea or further treatment of exfoliated g-C(3)N(4)by mesylchloride. Synthesized materials were applied for photocatalytic removal of air pollutants (acetaldehyde and NOx) according to the ISO 22197 and ISO 22197-1 methodology. The efficiency of acetaldehyde removal under UV irradiation was negligible for all g-C(3)N(4)samples. This can be explained by the fact that g-C(3)N(4)under irradiation does not directly form hydroxyl radicals, which are the primary oxidation species in acetaldehyde oxidation. It was proved by electron paramagnetic resonance (EPR) spectroscopy that the dominant species formed on the irradiated surface of g-C(3)N(4)was the superoxide radical. Its production was responsible for a very high NO(x)removal efficiency not only under UV irradiation (which was comparable with that of TiO2), but also under visible irradiation.Web of Science1313art. no. 303

Scaling up anodic TiO2 nanotube layers - Influence of the nanotube layer thickness on the photocatalytic degradation of hexane and benzene

In this work, the preparation of homogenous TiO2 nanotube (TNT) layers with different thicknesses via anodization on Ti substrates with a large geometrical area of two times 5 cm x 10 cm (i.e. both sides of the Ti substrate) is shown for the first time. TNT layers with four different thicknesses of similar to 0.65 mu m, similar to 1 mu m, similar to 7 mu m, and similar to 14 mu m were prepared with excellent conformality and homogeneity over the anodized area. These TNT layers were successfully employed as photocatalysts for the degradation of hexane and benzene as model compounds in the gas phase under ISO standards, showing an increase of the conversion for both model compounds with the TNT layer thickness. While a stable hexane conversion was observed for all TNT layers during the measuring time of three hours, in case of benzene degradation an initial conversion decrease was monitored before the conversion stabilized. Despite this trend, SEM and XPS analyses did not reveal any significant amount of reaction products on the TNT layer surface

Nemzeti érdekek az EU-ban. Az olasz európa-politika tanulságai, különös tekintettel az európai gazdasági kormányzásban betöltött szerepre = National Interests in the EU. Experiences of Italy’s European policy with special regard to its role in the European economic governance

A disszertáció a hazai és a nemzetközi szakirodalom elemzésén keresztül vizsgálja a nemzeti és az európai (közösségi) érdek viszonyát, ezek alakulását az integrációs folyamatban. Választ próbál találni arra, hogy mi a fő oka annak az utóbbi évtizedben egyre inkább erősödő jelenségnek, amely az EU nemzetek feletti jellegének visszaszorulásában, és ezzel párhuzamosan a közösségi szakpolitikák alakításakor a kormányközi logika érvényesülésének erősödésében összegezhető. Az elemzés során nem lehet eltekinteni az európai integráció társadalmi aspektusaitól, így ezek között kiemelten a projekttel való lakossági azonosulás, más szóval az egyébként sokdimenziós, tagállamonként és időben változó identitás problematikájától. A dolgozat kiemelten foglalkozik az olasz Európa-politika fejlődésével és érvényesülésével. Róma EU-politikájának elemzése már csak azért is érdekes feladat, mert Itália európai középhatalmi státuszából adódóan az a klasszikus közösségi-államközi, látszólag ellentétes „módszer” metszéspontjában található. Megnyilvánulási formái ennek megfelelően – a külső szemlélő számára akár bizonytalankodásnak hatóan - váltakozó hangsúllyal ötvözik a nemzetek feletti és a kormányközi stratégiát. Az olasz integrációs politika hagyományainak, általános geopolitikai-külpolitikai keretrendszerének, változásainak részletes elemzése elengedhetetlen az egyes szakpolitikák terén tanúsított olasz törekvések megértéséhez. (...

Transparent Nanotubular TiO2 Photoanodes Grown Directly on FTO Substrates

This work describes the preparation of transparent TiO2 nanotube (TNT) arrays on fluorine-doped tin oxide (FTO) substrates. An optimized electrolyte composition (0.2 mol dm−3 NH4F and 4 mol dm−3 H2O in ethylene glycol) was used for the anodization of Ti films with different thicknesses (from 100 to 1300 nm) sputtered on the FTO glass substrates. For Ti thicknesses 600 nm and higher, anodization resulted in the formation of TNT arrays with an outer nanotube diameter around 180 nm and a wall thickness around 45 nm, while for anodized Ti thicknesses of 100 nm, the produced nanotubes were not well defined. The transmittance in the visible region (λ = 500 nm) varied from 90% for the thinnest TNT array to 65% for the thickest TNT array. For the fabrication of transparent TNT arrays by anodization, the optimal Ti thickness on FTO was around 1000 nm. Such fabricated TNT arrays with a length of 2500 nm exhibit stable photocurrent densities in aqueous electrolytes (~300 µA cm−2 at potential 0.5 V vs. Ag/AgCl). The stability of the photocurrent response and a sufficient transparency (≥65%) enables the use of transparent TNT arrays in photoelectrochemical applications when the illumination from the support/semiconductor interface is a necessary condition and the transmitted light can be used for another purpose (photocathode or photochemical reaction in the electrolyte)

Scaling up anodic TiO2 nanotube layers for gas phase photocatalysis

In this work, for the first time, an anodic TiO2 nanotube layer of large area (~50 cm2), was used for the photocatalysis in the gaseous phase. Hexane was chosen as model pollutant. The nanotube layer showed a superior efficiency compared to a reference TiO2 layer of the same thickness composed of immobilized P25 nanoparticles. An additional TiO2 coating of the nanotube layer produced by atomic layer deposition did not show an enhancement of the photocatalytic degradation of hexane due to a decreased active surface area, in contrast to the liquid state photocatalysis under applied external potentia

Photochemical stability of g-C3N4 in the gas phase

For the successful environmental applications of g-C3N4 photocatalyst, sufficient photochemical stability is an important parameter. The present work is thus devoted to the investigation of the photostability of g-C3N4 materials in terms of production of organic compounds under UV and VIS light irradiation; for the purpose of comparison, TiO2 material was also investigated. The measurement of total organic compounds in air shows the production of organic compounds when g-C3N4 materials are irradiated with UV or VIS light. Detailed analysis of organic compounds present in the air was performed using GC-MS. When both materials (TiO2 and g-C3N4) were exposed in the dark, the air contained traces of ordinary solvents (acetone, hexane, ethyl acetate). In the case of TiO2, after 1 day of UV irradiation, all organic compounds were removed. Contrary to it, in the case of exfoliated g-C3N4, the concentration of acetone after UV or VIS irradiation increased. The solid-state measurements indicate that after UV/VIS light exposure, there are no changes either in the surface layers or in the bulk of the g-C3N4 photocatalyst. However, based on the observed mass decrease and elemental analysis, the material is oxidised on the surface, and it seems that this surface reaction leads to the disruption of the C-N bonds and the formation of organic compounds, which are released into the atmosphere. But, no compounds containing nitrogen were determined by MS, so nitrogen is most probably released in the form of NOx.Web of Science103art. no. 10764

2D MoS2 nanosheets on 1D anodic TiO2 nanotube layers: an efficient co-catalyst for liquid and gas phase photocatalysis

One-dimensional TiO2 nanotube layers with different dimensions were homogeneously decorated with 2D MoS2 nanosheets via atomic layer deposition and employed for liquid and gas phase photocatalysis. The 2D MoS2 nanosheets revealed a high amount of exposed active edge sites and strongly enhanced the photocatalytic performance of TiO2 nanotube layers