Photocatalytic oxidation of gaseous benzene,toluene and xylene under UV and visible irradiation over Mn-doped TiO_(2)nanoparticles

The photocatalytic oxidation of gaseous benzene,toluene and xylene(BTX)over un-doped,0.1 and 1 wt%Mn-TiO_(2)nanoparticles under ultraviolet and visible irradiation was studied in atmosphere of synthetic air or inert gas.The photocatalytic decomposition efficiency and the oxidation products were determined using a Static Photochemical Reactor coupled with FTIR spectroscopy.BTX underwent efficient decomposition over Mn-TiO_(2)photocatalysts under UV irradiation,more with oxygen presence and less without oxygen.More important toluene and xylene went substantial decomposition over 0.1 mol%Mn-TiO_(2)under visible irradiation with oxygen presence.The main final oxidation products in the UV photocatalysis of BTX were CO_(2),CO and H2O,with CO_(2) and CO yields 4 and 2 respectively.The conversion percentage of benzene,toluene,and xylene to CO_(2) were 63.6%,56.4%,51.8%,and to CO 29%,26.5%,23.2%,respectively.In the visible photocatalysis of toluene and xylene the yields of CO were insignificant.Formation of carbon containing deposits on TiO_(2)surfaces was observed after extensive UV photocatalysis of toluene and xylene,and such by-products surface coverage may reduce the photocatalytic activity of TiO_(2)samples.Some aspects of the photocatalytic mechanism were examined.

Modified TiO_(2) based photocatalysts for improved air and health quality

Photocatalysis with modified titania is a promising approach to improve both air and health quality.Modified titania with novel photocatalytic properties under indoor light irradiation leads to smart coatings,which are benchmark materials suitable for their indoor applications.It is generally accepted that the photocatalytic activity is affected by the light absorption,charge creation/recombination rate and surface reactivity.In this contribution we focus on modified TiO_(2) as catalyst in heterogeneous photocatalytic processes and address the efficiency of TiO_(2)-based building and construction materials on the removal of environmental pollutants indoors and outdoors.We also present data on the presence of eventually formed,toxicologically relevant and harmful by-products as the result of the photo-induced degradation of pollutants in an effort for better evaluation of induced risks for human health from the application of TiO_(2) modified materials.Finally,we present recent results on the disinfection performance of these material and the inactivation of severe pathogens contained in water and indoor air environments.

An overview of photocatalytic materials

Photocatalysis is an emerging technology that enables a wide variety of applications,including degradation of organics and dyes,antibacterial action,and fuel generation through water splitting and carbon dioxide reduction.Numerous inorganic semiconducting materials have been explored as photocatalysts,and the versatility of these materials and reactions has been expanded in recent years.Understanding the relationship between the physicochemical properties of photocatalytic materials and their performances as well as the fundamentals in catalytic processes is important to design and synthesis of photocatalytic materials.

Highly sensitive ozone and hydrogen sensors based on perovskite microcrystals directly grown on electrodes

Highly-sensitive and stable ozone and hydrogen sensing elements were fabricated based on well-crystalline rounded cube-shaped CsPbBr 3 microcrystals,synthesized by a facile solution process per-formed under ambient conditions.It is shown that such elements demonstrate enhanced room tem-perature gas sensing ability compared to the previously reported metal halide and oxide-based ones.Electrical measurements performed on these sensing components revealed high sensitivity to ultra-low ozone and hydrogen concentrations,namely 4 ppb and 1 ppm respectively,as well as a remarkable repeatability,even after a few months of storage in ambient conditions.Both ozone and hydrogen sensors were self-activated,as they did not require the use of UV or heating external stimuli to operate,and exhibited fast detection and short restoration times.All such attractive properties along with the simple fabrication process could provide an easy,efficient and low-cost technology for the realization of future gas sensing devices.

Porous Co_(x)Ni_(1-x)TiO_(3) nanorods for solar photocatalytic degradation of ethyl paraben

Porous Porous Co_(x)Ni_(1-x)TiO_(3) nanorods were successfully synthesized through a solution-based method following an ethylene glycol route at room temperature.The effect of calcination temperature from 300℃to 900℃ for NiTiO_(3) and CoTiO_(3) nanorods was studied using X-ray diffractometry and scanning electron microscopy in order to investigate their structural and morphological properties.The optimum calcination temperature to prepare pure ilmenite type structure rods with high crystallinity and hexagonal shape was 600Co_(x)Ni_(1-x)TiO_(3) exhibited the highest photocatalytic activity for the degradation of ethyl paraben,an endocrine disrupting compound,under simulated solar or visible light irradiation.Nearly complete(i.e.92%)paraben degradation occurred after 5 h of solar irradiation and this decreased to 48%when only the visible part of the radiation was employed.The solar photocatalytic activity of CoTiO_(3) and NiTiO_(3) was found to be 42%and 67%,respectively.