Ti-based porous materials for reactive oxygen species mediated photocatalytic reactions

Reactive oxygen species (ROS) are highly reactive oxidants that are typically generated by the irradiation of semiconducting materials with visible or UV light and are widely used for the photocatalytic...

THE USE OF PHOTOCATALYTIC CONCRETES IN ROAD CONSTRUCTION

The article discusses the possibility of reducing the atmospheric environmental load of highways by applying compositions with photocatalytic properties to acoustic screens. It is found that the amount of nitrogen oxides on the territory of the city of Moscow exceeds the MPC norms. Therefore, a potential way to reduce the level of the average daily and maximum one-time MPC of nitrogen oxides is proposed, when using coatings of traditional acoustic screens with photocatalytic compositions. Titanium dioxide in anatase form is considered as a photocatalytic agent. To reduce the density and increase the porosity of cement compositions, a cellulosic suspension obtained by saturation in an aqueous medium with subsequent homogenization is introduced. The effect of cellulose in the considered cement systems in combination with a photocatalytic agent has been investigated. By the method of mathematical planning, a two-factor compositional experiment is compiled. In result, the degrees of influence of titanium dioxide and cellulose additives on the strength, density and water absorption of the composites under study are established. The study of the structure of the obtained composites shows that TiO2 is mainly located on the surface of cellulose fibers, which theoretically increases the useful surface for photocatalytic reactions and, as a consequence, the final efficiency of the compositions.

Defective Grey TiO2 with Minuscule Anatase–Rutile Heterophase Junctions for Hydroxyl Radicals Formation in a Visible Light-Triggered Photocatalysis

The novelty of this work was to prepare a series of defect-rich colored TiO2 nanostructures, using a peroxo solvothermal-assisted, high-pressure nitrogenation method. Among these solids, certain TiO2 materials possessed a trace quantity of anatase–rutile heterojunctions, which are beneficial in obtaining high reaction rates in photocatalytic reactions. In addition, high surface area (above 100 m2/g), even when utilizing a high calcination temperature (500 °C), and absorption of light at higher wavelengths, due to the grey color of the synthesized titania, were observed as an added advantage for photocatalytic hydroxyl radical formation. In this work, we adopted a photoluminescent probe method to monitor the temporal evolution of hydroxyl radicals. As a result, promising hydroxyl radical formations were observed for all the colored samples synthesized at 400 and 500 °C, irrespective of the duration of calcination.

NEW ANTIMICROBIAL STRATEGIE USING COMPOSITIONS WITH PHOTOCATALYTIC PROPERTIES

The paper describes the studies started by an inter-disciplinary team in finding a disinfection method using a coating with photocatalytically activated antimicrobial properties by visible spectrum radiation. An own method of preparation led to the obtaining of a photocatalytic pigment based on copper-doped titanium dioxide to move the activation spectrum to the visible range. The preparation method was designed so as to allow transposition into industrial production. The demonstration and measurement of the photocatalytic effect for certification as an industrial product was done based on an adapted method, starting from two existing standards. A washable paint containing the photocatalytic pigment was tested "in situ", the results demonstrating the reduction of microbial load. The paper is based on current knowledge about light-activated antimicrobiological agents (LAAs) in an attempt to further the study of visible spectrum radiation, which in combination with a series of photosensitizers excited by this radiation, have the role of generating photocatalytic reactions with disinfection effect.

Photocatalytic Properties of Silver Nanospherical Arrays Driven by Surface Plasmons

Surface-enhanced Raman scattering (SERS) is a promising technique to study the plasma-driven photocatalytic reactions. Hemispherical alumina nanoarrays with a regular hexagonal arrangement are firstly prepared; then, silver hemispherical nanoarrays are synthesized on the surface of the arrays by silver evaporation. When a laser with a specific wavelength (633 nm) is irradiated on the silver nanoarrays, a large number of regularly arranged local surface plasmon enhancement regions (called “hot spots”) would be generated on its surface. After that, a layer of evenly distributed p-aminothiophenol (PATP) probe molecules was placed on the substrate and the photocatalytic reaction of PATP was driven by the local surface plasmon to form four 4′-di-mercaptoazobenzene (DMAB). Then, under the same experimental conditions, the later product was reversely reacted to form PATP molecule by the action of plasma in the presence of in situ sodium borohydride. SERS can be used to monitor the whole process of the photocatalytic reaction of PATP probe molecules driven by the plasma on the surface of the silver nanoarrays. This research achieves the drawing and erasing of molecular graphics in the micro- and nano-scales, as well as information encryption, reading, and erasing that have strong application value.

Novel Ternary Metal Oxide Nanoparticles (La2Cu0.8Zn0.2O4) as Potential Photocatalyst for Visible Light Photocatalytic Degradation of Methylene Blue and Desulfurization of Dibenzothiophene

In this work, we present preparation of novel ternary metal oxide nanoparticles, La2Cu0.8Zn0.2O4 (LCZO), using simple co-precipitation method. The crystalline structure, morphology and composition of the prepared LCZO nanoparticles were characterized by XRD, SEM and EDX analysis. The DRS investigation shows the LCZO nanoparticles have considerable light absorption in the visible light region. Also, the LCZO nanoparticles possess the band-gap energy of 2.82 eV. To investigate the visible light photocatalytic potential of the prepared LCZO nanoparticles, two photocatalytic reactions were conducted toward degradation of methylene blue (MB) solution and desulfurization of dibenzothiophene (DBT). In the presence of 3:1 molar ratio of H2O2/DBT, the high photocatalytic desulfurization rate (93.7%) of dibenzothiophene (DBT) was obtained over 0.2 gr of LCZO photocatalyst. In addition, the photocatalytic degradation rate of methylene blue (MB) solution was 91.4%. The mechanism involving both photocatalytic reactions were studied using different radical scavenging agents which showed that the hydroxyl radicals (OH•) are responsible for highly efficient desulfurization and degradation reactions. Moreover, reusability experiments reveal that the prepared LCZO photocatalyst has great stability and recyclability for both desulfurization of DBT and degradation of MB after 6 reaction cycles.

A response surface model to predict and experimentally tune the chemical, magnetic and optoelectronic properties of oxygen-doped boron nitride

A new material platform for boron nitride (BN) as a heterogeneous photocatalyst for solar fuels synthesis has recently emerged. One of the bottlenecks of this material is the lack of photoactivity under visible light, which hinders its rate performance. Theoretical studies have predicted that tuning the oxygen content in oxygen-doped BN (BNO) might be used to lower and vary the band gap. However, this is yet to be verified experimentally. We present herein a systematic experimental route facilitating simultaneous tuning of the chemical, magnetic and optoelectronic properties of BNO using a multivariate synthesis parameter space. Deep visible range band gaps (1.50 – 2.90 eV) were experimentally achieved and tuned over an oxygen composition of 2 – 14 at. %, and specific paramagnetic OB3 content of 7 – 294 a.u. g-1, thus supporting theoretical predictions. Through designing a response surface via a design of experiments (DOE) process, the key synthesis parameters influencing the chemical, magnetic and optoelectronic properties of BNO were identified. In addition, model prediction equations relating the aforementioned properties to the synthesis parameter space are presented. Accurate model predictions for the oxygen content and band gap were conducted and validated experimentally. Such a methodology is valuable for further advances in tailoring and optimising BN materials for heterogeneous photocatalytic reactions.