Photocatalysis

About: Photocatalysis is a research topic. Over the lifetime, 67088 publications have been published within this topic receiving 2145233 citations. The topic is also known as: photocatalyst.

Visible-light-induced photocatalysis through surface plasmon excitation of gold on titania surfaces

Abstract: Fifteen commercial titania (titanium(IV) oxide; TiO2) powders were modified with gold by photodeposition to prepare photocatalysts that work under irradiation with light in the visible range (vis). The gold-modified titania (Au/TiO2) powders were characterized by diffuse reflectance spectroscopy (DRS), field-emission scanning electron microscopy (FE-SEM), scanning transmission microscopy (STEM) and X-ray powder diffraction (XRD). It was shown that all tested powders could absorb visible light with an absorption maximum at localized surface plasmon resonance (LSPR) wavelengths (530–600 nm) and that the size and shape of gold nanoparticles determined the absorption ranges. The photocatalytic activity of Au/TiO2 powders was examined both under ultraviolet and vis irradiation (mainly >450 nm) for acetic acid and 2-propanol photooxidation. It was found that the activity depended strongly on gold and titania properties, such as particle size and shape, surface area and crystalline form. Under vis irradiation, large rutile particles loaded with gold particles of a wide range of sizes showed the highest level of photocatalytic activity, possibly due to greater light absorption ability in a wide wavelength range resulting from transverse and longitudinal LSPR of rod-like gold particles. Action spectrum analyses showed that visible-light-induced oxidation of organic compounds by aerated gold–titania suspensions was initiated by excitation of LSPR absorption of gold. Although photocatalytic activity of nanosized gold particles under vis irradiation with a wavelength of ca. 430 nm and catalytic activity of gold-modified titania during dark reactions were also found, it was shown that the activities of Au/TiO2 particles originated from activation of LSPR of gold by light of wavelength of 530–650 nm. Participation of molecular oxygen as an electron acceptor and titania as a conductor of electrons is suggested by comparing with results obtained under deaerated conditions and results obtained using a system containing gold-deposited silica instead of gold–titania, respectively. On the basis of these results, the mechanism of visible-light-induced oxidation of organic compounds on gold–titania is proposed.

Characterization of Fe–TiO2 photocatalysts synthesized by hydrothermal method and their photocatalytic reactivity for photodegradation of XRG dye diluted in water

Abstract: Iron-ion-doped anatase titanium (IV) dioxide (TiO2) samples were prepared by hydrothermal hydrolysis and crystallization in octanol-water solution. The samples were characterized by X-ray diffraction, BET-specific surface area determination, UV-Vis diffuse reflectance spectroscopy and electron paramagnetic resonance spectroscopy. UV-Vis diffuse reflectance spectra showed a slight shift to longer wavelengths and an extension of the absorption in the visible region for almost all the ion-doped samples, compared to the non-doped sample. The photocatalytic activity of those catalysts was investigated for the liquid phase photocatatlytic degradation of active yellow XRG dye diluted in water under UV and visible light irradiation. It was found that the catalysts doped with FeCl3 have better catalytic activity for photodegradation of XRG than those doped with FeCl2. The amount of doped iron ion plays a significant role in affecting its photocatalytic activity and iron doped with optimum content can enhance photocatalytic activity, especially under visible light irradiation.

Zn1–xCdxS Solid Solutions with Controlled Bandgap and Enhanced Visible-Light Photocatalytic H2-Production Activity

Abstract: Photocatalytic hydrogen (H2) production from water splitting under visible-light irradiation is considered to be an attractive way to solve the increasing global energy crises in modern life. In this study, highly efficient photocatalytic H2 production without the assistant of a cocatalyst was achieved using Zn11–xCdxS solid solutions as the visible-light-driven photocatalysts and a mixed Na2S and Na2SO3 aqueous solution as the sacrificial reagent. The Zn1–xCdxS samples were prepared by a simple zinc–cadmium–thiourea (Zn–Cd–Tu) complex thermolysis method using thiourea, zinc acetate (Zn(Ac)2), and cadmium acetate (Cd(Ac)2) as the precursors. The obtained Zn1–xCdxS solid solutions feature a small crystallite size and precisely controllable band structure, which are beneficial for the photocatalysis. When the Zn/Cd molar ratio is 1:1, the prepared Zn0.5Cd0.5S sample exhibits the highest H2-production rate of 7.42 mmol·h–1·g–1, exceeding that of the pure CdS and ZnS samples by more than 24 and 54 times, resp...

Photocatalytic Water Treatment by Titanium Dioxide: Recent Updates

Abstract: Photocatalytic water treatment using nanocrystalline titanium dioxide (NTO) is a well-known advanced oxidation process (AOP) for environmental remediation. With the in situ generation of electron-hole pairs upon irradiation with light, NTO can mineralize a wide range of organic compounds into harmless end products such as carbon dioxide, water, and inorganic ions. Photocatalytic degradation kinetics of pollutants by NTO is a topic of debate and the mostly reporting Langmuir-Hinshelwood kinetics must accompanied with proper experimental evidences. Different NTO morphologies or surface treatments on NTO can increase the photocatalytic efficiency in degradation reactions. Wisely designed photocatalytic reactors can decrease energy consumption or can avoid post-separation stages in photocatalytic water treatment processes. Doping NTO with metals or non-metals can reduce the band gap of the doped catalyst, enabling light absorption in the visible region. Coupling NTO photocatalysis with other water-treatment technologies can be more beneficial, especially in large-scale treatments. This review describes recent developments in the field of photocatalytic water treatment using NTO.