Functionalised exposed building materials: Self-cleaning,photocatalytic and biofouling abilities

With the advent of urbanisation, there was a considerable and progressive worsening of urban air quality. Amongst the solutions proposed by scientific research, photocatalysis proved itself to be one of the most promising. In the present work, commercial glazed ceramic tiles were functionalised with a micrometric TiO₂ layer adopting an industrial-like process. It was purposely chosen to avoid the use of nanoparticles because they might be inhaled and come into direct contact with the cells of the human organism during the industrial processing. Additionally, the self-cleaning, photocatalytic – the former by means of liquid-solid phase photocatalytic tests and water contact angle measurements; the latter against nitrogen oxides abatement – and biofouling abilities of the functionalised materials were thoroughly investigated. Results showed that the functionalised glazed ceramic tile possessed excellent self-cleaning and photocatalytic properties. As per the algal growth, surface roughness showed itself to be a key-point: the TiO₂ surface layer, giving the material a higher surface roughness compared to the untreated one, had an accelerated algal growth process.     

Synthetic zeolite supported ZnO nanoparticle materials for photocatalytic applications

Abstract

Nanosize zinc oxide (ZnO) particles were supported on a suitable, inert and porous zeolite by a simple hydrothermal and sol–gel method in order to maximise adsorption and photocatalytic performance as well as retrievability and cost down. The effects of zeolite type, soak cycles, soak temperature and soak time of ZnO/zeolite composite materials on photocatalytic activity were discussed, which showed that the degradation of methylene blue dye in water can reach 91% after 150 min under UV light irradiation using synthetic zeolite as the supporting material with single soak cycles for 15 min under 50°C.     

Degradation of organic pollutants in water by photochemical reactors

The degradation of glycolic acid in aqueous media was performed by homogeneous photochemical and heterogeneous photocatalytic processes using different kinds of chemical reactors. The efficiency of the degradation processes was evaluated by measuring both the reactant conversion and the decrease of the total organic carbon (TOC) of the solution. The best results were obtained by using a continuous reactor with a fixed supported photocatalyst.     

Metal oxide mesocrystals and mesoporous single crystals: synthesis,properties and applications in solar energy conversion

Metal oxide mesocrystals (MCs) and mesoporous single crystals (MSCs) exhibit superior carrier transport ability,high specific surface area,shortened photo-carrier diffusion lengths to interfaces and enhanced absorbance of the incident sunlight.These advanced features make metal oxide MCs and MSCs be a promising candidate material in photocatalysis,photoelectrocatalysis,dye sensitized solar cells (DSSCs) and perovskite solar cells (PSCs).Recently,remarkable advances of applying metal oxide MCs and MSCs in these areas have been achieved.Therefore,it is extremely important to deeply understand the influence of the unique properties of metal oxide MCs and MSCs on solar energy conversion systems.Herein,we presented a brief introduction on the synthesis and carrier transfer behavior of metal oxide MCs and MSCs.Then,the rational structure design and modification of metal oxide MCs and MSCs for photocatalysis,photoelectrocatalysis,DSSCs and PSCs are systematically discussed.Finally,the perspectives on extending the application of metal oxide MCs and MSCs are addressed.     

New insights into the mechanism of photocatalytic hydrogen evolution from aqueous solutions of saccharides over CdS-based photocatalysts under visible light

A new multiphase photocatalyst – 1%Pt/Cd_0.6Zn_0.4S/Cd_0.1Zn_0.9S – was synthesized by a simple hydrothermal treatment of as-prepared Cd_0.3Zn_0.7S solid solution and thoroughly characterized by different methods. The activity was tested in a sustainable process of hydrogen evolution from aqueous solutions of two saccharides (glucose and xylose) under visible light. The mechanism of the photocatalytic hydrogen evolution from complex organic substrates is still controversial. In this research it was shown that optimizing the experimental conditions (pH, substrate concentration) leads to a significant increase in the photocatalytic activity for both saccharides. A kinetic equation based on a Langmuir model and including the degree of dissociation of the substrate was proposed and verified for the first time. The highest activities during hydrogen evolution for glucose and xylose were achieved in strongly alkaline media. The photocatalyst 1%Pt/CdZnS120 possessed an activity equal to 3.4 mmol H₂ h⁻¹ g⁻¹ (glucose, apparent quantum efficiency 8.4%), that exceeds recently reported values.     

内建电场调控光生电荷分离效率的研究进展

光催化技术是解决现今环境污染和能源危机的重要手段之一,然而大部分催化剂的光催化效率较低,提高光生电荷的分离是提高光催化效率的一种有效方法.首先对催化剂的光催化原理进行了概述;结合近年来国内外在提高光生电荷分离效率方面取得的最新成果及进展,从内建电场的产生机理入手,综述了半导体p-n结、异相结、极化表面和铁电材料极化对光...     

One step room temperature photodeposition of Cu/TiO2 composite films and its conversion to CuO/TiO2

Cu/TiO₂ composite films were prepared at low temperature on glass substrates by a photodeposition method. Films were deposited by irradiating the substrate while in contact with an aqueous TiO₂ suspension containing copper(II) nitrate and ethanol. Cu/TiO₂ composite films of 500 nm in thickness were deposited at room temperature after a short irradiation time (15 min) with a 125 W mercury vapour lamp. According to scanning electron microscopy observations, the obtained films were homogeneous and porous. Energy dispersive X-ray spectroscopy analysis revealed a 3:1 Cu:Ti atomic ratio. Grazing angle X-ray diffraction analysis showed that the films contained Cu and TiO₂ as major components and Cu₂O as a minor component. Heat treatment at 400 °C in air for a period of 3 h transformed the initial material into a CuO/TiO₂ composite, improved the adhesion to the substrate and favoured a more regular distribution of copper oxide according to backscattering micrographs.     

CuxNi1-xO nanostructures and their nanocomposites with reduced graphene oxide: Synthesis,characterization, and photocatalytic applications

NiO nanostructure was synthesized using a simple co-precipitation method and was embedded on reduced graphene oxide surface via ultrasonication. Structural investigations were made through X-ray diffraction (XRD) and functional groups were confirmed by Fourier transform infrared spectroscopy (FTIR). XRD analysis revealed the grain size reduction with doping. Fourier transform infrared spectroscopy confirmed the presence of metal-oxygen bond in pristine and doped NiO nanostructure as well as the presence of carbon containing groups. Scanning electron microscopy (SEM) indicated that the particle size decreased when NiO nanostructure was doped with copper. BET surface area was found to increase almost up to 43 m²/g for Cu doped NiO nanostructure/rGO composite. Current-voltage measurements were performed using two probe method. UV–Visible spectroscopic profiles showed the blue and red shift for Cu doped NiO nanostructure and Cu doped NiO Nanostructure/rGO composite respectively. Rate constant for Cu doped NiO nanostructure/rGO composite found to increase 4.4 times than pristine NiO nanostructure.     

Electrospun Zn-doped Ga2O3 nanofibers and their application in photodegrading rhodamine B dye

Ultrawide band gap semiconductor materials have attracted considerable attention in recent years owing to their great potential in the photocatalytic field. In this study, Zn-doped Ga₂O₃ nanofibers with various concentrations were synthesized via electrospinning; they exhibited a superior photocatalytic degradation performance of rhodamine B dye compared to that of undoped Ga₂O₃ nanofibers. The Zn dopant replaced Ga sites via replacement doping, which could increase the concentration of oxygen vacancies and lead to enhanced photocatalytic properties. When the Zn concentration increased, a Ga₂O₃/ZnGa₂O₄ hybrid structure formed, which could further enhance the photocatalytic performance. The separation of photogenerated carriers due to Zn doping and heterojunctions were the primary causes of the enhanced photocatalytic performance. This study provides experimental data for the fabrication of high-performance photocatalysts based on Ga₂O₃ nanomaterials.     

Synthesis, structure characterization and photocatalytic properties of two new uranyl naphthalene-dicarboxylate coordination polymer compounds

Two new uranyl-organic coordination compounds, UO₂(NDC)[(CH₃)₂SO)]₂ (1) and [UO₂(NDC)(CH₂OH)₂] (2) (H₂NDC = 1,4-naphthalene dicarboxylate), have been synthesized from the solutions of dimethyl sulfoxide (DMSO) and ethylene glycol (EG), respectively, through a volatilization method. Single-crystal X-ray diffraction analyses show that compound 1 consists of novel straight chains modified by pairs of DMSO molecules, whereas compound 2 features one-dimensional zigzag chains which are cross-linked by non-coordinating solvent molecules through hydrogen bonding interactions, forming a two-dimensional network. Both 1 and 2 decompose rhodamine B (RhB) molecules efficiently under the irradiation of UV and visible light.