Exploring the Molecular Structure and Treatment Dynamics of Cellulose Fibres with Photoacoustic and Reversed Double-Beam Spectroscopy.

In this study, we explored the structural and chemical modifications of cellulose fibres subjected to chemical and mechanical treatments through an innovative analytical approach. We employed photoacoustic spectroscopy (PAS) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) to examine the morphological changes and the chemical integrity of the treated fibres. The methodology provided enhanced sensitivity and specificity in detecting subtle alterations in the treated cellulose structure.

Ultrasonic-Induced Surface Disordering Promotes Photocatalytic Hydrogen Evolution of TiO.

Surface disordering has been considered an effective strategy for tailoring the charge separation and surface chemistry of semiconductor photocatalysts. A simple but reliable method to create surface disordering is, therefore, urgently needed for the development of high-performance semiconductor photocatalysts and their practical applications. Herein, we report that the ultrasonic processing, which is commonly employed in the dispersion of photocatalysts, can induce the surface disordering of TiO and significantly promote its performance for photocatalytic hydrogen evolution.

Defective TiO Nanotube Arrays for Efficient Photoelectrochemical Degradation of Organic Pollutants.

Oxygen vacancies (OVs) are one of the most critical factors that enhance the electrical and catalytic characteristics of metal oxide-based photoelectrodes. In this work, a simple procedure was applied to prepare reduced TiO nanotube arrays (NTAs) (TiO) via a one-step reduction method using NaBH. A series of characterization techniques were used to study the structural, optical, and electronic properties of TiO NTAs.

Formation of a Nanorod-Assembled TiO Actinomorphic-Flower-like Microsphere Film via Ta Doping Using a Facile Solution Immersion Method for Humidity Sensing.

This study fabricated tantalum (Ta)-doped titanium dioxide with a unique nanorod-assembled actinomorphic-flower-like microsphere structured film. The Ta-doped TiO actinomorphic-flower-like microsphere (TAFM) was fabricated via the solution immersion method in a Schott bottle with a home-made improvised clamp. The samples were characterised using FESEM, HRTEM, XRD, Raman, XPS, and Hall effect measurements for their structural and electrical properties.

Development of Sulfur-Doped Graphitic Carbon Nitride for Hydrogen Evolution under Visible-Light Irradiation.

Developing eco-friendly strategies to produce green fuel has attracted continuous and extensive attention. In this study, a novel gas-templating method was developed to prepare 2D porous S-doped g-CN photocatalyst through simultaneous pyrolysis of urea (main g-CN precursor) and ammonium sulfate (sulfur source and structure promoter). Different content of ammonium sulfate was examined to find the optimal synthesis conditions and to investigate the property-governed activity.

Are you still using organic dyes? Colorimetric formaldehyde analysis for true photocatalytic-activity evaluation.

We report easily available and highly reliable colorimetric formaldehyde analysis using only a spectrophotometer/colorimeter, which enables the evaluation of the "true" photocatalytic activity induced by photoabsorption of a "photocatalyst", compared with gas-chromatographic analyses of gaseous products, even though the reliability of colorimetric organic-dye analysis is much worse under visible-light irradiation.

Reversed double-beam photoacoustic spectroscopic analysis of photoinduced change in absorption of cellulose fibres.

Photoabsorption properties of cellulose fibres under continuous and modulated irradiation were investigated in situ by the use of reversed double-beam photoacoustic spectroscopy (RDB-PAS). This photoacoustic (PA) measurement enabled observation of ultraviolet- and visible light-induced, electron trap filling, and reductive change on the surface of the fibres. Energy-resolved measurements and analysis of the kinetics of photoinduced de-excitation suggested that electrons that accumulated in the different cellulose crystalline phases had moderate reactivity toward molecular oxygen.

Efficient photocatalytic degradation of emerging ciprofloxacin under visible light irradiation using BiOBr/carbon quantum dot/saponite composite.

The use of visible-driven photocatalysts has fascinated attention as a capable and sustainable approach for wastewater remediation. In this work, BiOBr/carbon quantum dot (CQDs)/saponite composites (CQDs/Clay@BiOBr) were fabricated via hydrothermally using two different CQDs/Clay precursors (in-situ synthesis (IS) and physical mixing (PM)). The obtained products were characterized, and the photocatalytic performances of the prepared samples were evaluated in the photocatalytic decomposition of emerging ciprofloxacin (CIP) pharmaceutical waste.

The Influence of Metal-Doped Graphitic Carbon Nitride on Photocatalytic Conversion of Acetic Acid to Carbon Dioxide.

Metal-doped graphitic carbon nitride (MCN) materials have shown great promise as effective photocatalysts for the conversion of acetic acid to carbon dioxide under UV-visible irradiation and are superior to pristine carbon nitride (g-CN CN). In this study, the effects of metal dopants on the physicochemical properties of metal-doped CN samples (Fe-, Cu-, Zn-, FeCu-, FeZn-, and CuZn-doped CN) and their catalytic activity in the photooxidation of acetic acid were investigated and discussed for their correlation, especially on their surface and bulk structures. The materials in the order of highest to lowest photocatalytic activity are FeZn_CN, FeCu_CN, Fe_CN, and Cu_CN (rates of CO evolution higher than for CN), followed by Zn_CN, CuZn_CN, and CN (rates of CO evolution lower than CN).

Photocatalytic Activity of Radial Rutile Titanium(IV) Oxide Microspheres for Aerobic Oxidation of Organics.

Radial rutile TiO nanorod homomesocrystals (TiO -NR HOMCs) or the so-called "sea urchin-like TiO microspheres" were synthesized by using a hydrothermal method. TiO -NR HOMCs show photocatalytic activity for aerobic oxidative degradation of 2-naphthol under irradiation of UV- and visible light. Furthermore, extremely small iron oxide clusters were formed on the surface of TiO -NR HOMCs (FeO /TiO -NR HOMCs) by the chemisorption-calcination technique to reduce the band gap.

The role of the shell in core-shell-structured La-doped NaTaO photocatalysts.

NaTaO, a semiconductor with a perovskite structure, has long been known as a highly active photocatalyst for overall water splitting when appropriately doped with La cations. A profound understanding of the surface feature and why and how it may control the water splitting activity is critical because redox reactions take place at the surface. One surface feature characteristic of La-doped NaTaO is a La-rich layer (shell) capping La-poor bulk (core).

Combined Spectroscopic Methods of Determination of Density of Electronic States: Comparative Analysis of Diffuse Reflectance Spectroelectrochemistry and Reversed Double-Beam Photoacoustic Spectroscopy.

The diffuse reflectance spectroelectrochemistry (SE-DRS) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) provide unique, complementary information on the density of electronic states (DOS) in the vicinity of the conduction band bottom. The measurements are performed under quite different conditions, representing the solid/liquid and solid/gas interfaces in SE-DRS and RDB-PAS, respectively. DOS profiles obtained from both types of measurements can be considered as unique "fingerprints" of the tested materials.

Light intensity-dependence studies on the role of surface deposits for titania-photocatalyzed oxygen evolution: Are they really cocatalysts?

The effects of surface loading of iridium(II) oxide (IrO), manganese(IV) oxide (MnO), and cobalt(II) phosphate (CoPi) on the rate of photocatalytic oxygen evolution by anatase or rutile titania particles suspended in aqueous solutions of an electron acceptor, iodate ions, were studied by light intensity-dependence (LID) kinetic analyses. Although the role of these deposits has been reported to be a cocatalyst without showing results of any kinetic analysis, the present LID kinetic study suggested that the deposits may act as a "positive-hole capturer" for oxygen evolution, not as a cocatalyst for both metal oxides and CoPi. Further studies on the effects of loading amount, deposit types, titania crystalline type, and titania-particle size on the reaction order were also performed by LID analysis based on the proposed kinetic model.

Optically Transparent Colloidal Dispersion of Titania Nanoparticles Storable for Longer than One Year Prepared by Sol/Gel Progressive Hydrolysis/Condensation.

The molecular catalyst sensitized system (MCSS), where an excited molecular catalyst adsorbed on a semiconductor such as TiO injects electrons to the conduction band of the semiconductor leading to hydrogen evolution/CO reduction coupled with an oxidation of water on the molecular catalyst, has been one of the most probable candidates in the approach to artificial photosynthesis. For a full utilization of visible light, however, a serious light scattering of the aqueous suspension of TiO in the visible region, which is generally experienced, should be avoided. Here, we report a preparation of optically transparent colloidal dispersion of TiO by the sol/gel reaction of TiCl through progressive hydrolysis/condensation under the basic condition without any calcination processes.

Crystallization of well-defined anatase nanoparticles in SBA-15 for the photocatalytic decomposition of acetic acid.

Anatase nanoparticles with a size of 5 nm were prepared in mesoporous silica (SBA-15 with the pore diameter of 6 nm) by impregnation of the precursor derived from titanium tetraisopropoxide and subsequent heat treatment in air. The mesoporous structure of the anatase-silica hybrid and the size of the anatase particles were kept unchanged during the crystallization of anatase at 200-600 °C. The hybrids were applied as a photocatalyst for the decomposition of acetic acid in water under UV irradiation to find the heat treatment over 400 °C led to higher efficiency of the reaction (45-55 μmol h of carbon-dioxide production) over the samples heated at temperatures lower than 300 °C (3-14 μmol h of carbon-dioxide production).

Enhanced Solar Photothermal Catalysis over Solution Plasma Activated TiO.

Colored wide-bandgap semiconductor oxides with abundant mid-gap states have long been regarded as promising visible light responsive photocatalysts. However, their catalytic activities are hampered by charge recombination at deep level defects, which constitutes the critical challenge to practical applications of these oxide photocatalysts. To address the challenge, a strategy is proposed here that includes creating shallow-level defects above the deep-level defects and thermal activating the migration of trapped electrons out of the deep-level defects via these shallow defects.

Heterojunction of CuO nanoclusters with TiO for photo-oxidation of organic compounds and for hydrogen production.

Heterojunctions of small CuO nanoclusters (synthesized by radiolysis) with TiO (commercial P25) induced a photocatalytic activity under visible light irradiation in a wide range of wavelengths due to the narrow bandgap of CuO nanoclusters of around 1.7 eV. The optical, chemical, and electrical properties of these composite nanomaterials were studied.

Mono- and bimetallic (Pt/Cu) titanium(IV) oxide photocatalysts. Physicochemical and photocatalytic data of magnetic nanocomposites' shell.

Surface modification of titania with noble and semi-noble metals resulted in significant enhancement of photocatalytic activity. Presented data, showing the photocatalytic properties of TiO-M (where M is Pt and/or Cu) photocatalysts were further used as FeO@SiO/TiO-M magnetic nanocomposites shells in "Mono- and bimetallic (Pt/Cu) titanium(IV) oxide core-shell photocatalysts with Vis light activity and magnetic separability" [1]. Platinum and copper were photodeposited on four different titania matrices (commercial and self-obtained ones).

Fabrication and characterization of ternary sepiolite/g-CN/Pd composites for improvement of photocatalytic degradation of ciprofloxacin under visible light irradiation.

The development of high-quality photocatalytic materials for the degradation of organic pollutants under visible light irradiation is a vital field of research. In the present study, a composite of natural sepiolite clay and synthetic graphitic carbon nitride (CN) mixed with dispersed palladium nanoparticles was developed for the efficient photocatalytic degradation of ciprofloxacin (CIP) under visible light irradiation. The sepiolite, CN, and composite materials were characterized by several techniques.

Elucidation of the electron energy structure of TiO(B) and anatase photocatalysts through analysis of electron trap density.

A clear understanding of the electron energy structure of TiO(B)/anatase is needed to study the related catalytic reactions and design new composite photocatalysts. In this study, the electron energy structures of TiO(B) and anatase were estimated by analyzing the energy-resolved distribution of electron traps measured by reversed double-beam photoacoustic spectroscopy. In the mixture of TiO(B) and anatase, interfacial charge-transfer excitation from anatase to electron traps of TiO(B) was suggested.

Energy-resolved distribution of electron traps for O/S-doped carbon nitrides by reversed double-beam photoacoustic spectroscopy and the photocatalytic reduction of Cr(vi).

We report for the first time to our knowledge the identification of heteroatom-doped and undoped CN with the energy-resolved distribution of electron traps (ERDT) near the conduction band bottom position (CBB) using reversed double-beam photoacoustic spectroscopy. The ERDT/CBB pattern is used to classify the type of elemental doping in CN, related to photocatalytic efficiency.

Importance of ZnTiO Phase in ZnTi-Mixed Metal Oxide Photocatalysts Derived from Layered Double Hydroxide.

In this study, ZnTi-mixed metal oxides (ZTM), such as ZnTiO, were synthesized from ZnTi layered double hydroxides by varying the molar ratio of Zn/Ti, calcination temperatures, and synthesis methods (hydrothermal or reflux). The surface electronic characteristics of ZTM were investigated by the energy-resolved distribution of electron traps (ERDTs) using reversed double-beam photoacoustic spectroscopy. The ZTM samples obtained by conducting hydrothermal synthesis at 500 °C showed similar ERDT patterns independent of the molar ratio of Zn/Ti, although ZnTiO phase was not observed in the X-ray diffraction pattern, when the Zn/Ti ratio was high.

Inhibition of Fungal Growth Using Modified TiO with Core@Shell Structure of Ag@CuO Clusters.

The photocatalytic disinfection (PCD) properties of TiO have attracted attention in the research communities because the produced reactive oxygen species (ROS) allow destruction of different types of microbes, such as fungi, bacteria, viruses, algae, unicellular organisms, etc. on surfaces, in water, and in air. However, TiO requires UV irradiation to produce the ROS, which limits its photoactivity in indoor environments.

Carbon/Graphene-Modified Titania with Enhanced Photocatalytic Activity under UV and Vis Irradiation.

Laser synthesis was used for one-step synthesis of titania/graphene composites (G-TiO (C)) from a suspension of 0.04 wt% commercial reduced graphene oxide (rGO) dispersed in liquid titanium tetraisopropoxide (TTIP). Reference titania sample (TiO(C)) was prepared by the same method without graphene addition.

Octahedral Anatase Titania as Efficient Photocatalyst: Influence of Preparation Conditions.

Octahedral anatase particles (OAPs) belonging to faceted titania photocatalysts exhibit one of the highest photocatalytic activities among various titania photocatalysts, probably due to hindered recombination of charge carriers resulting from low content of defects (recombination centers). In this study, OAPs have been examined for oxidative decomposition of acetic acid, dehydrogenation of methanol and bacteria inactivation. OAPs were prepared from partly protonated potassium nanowires by hydrothermal reaction (HT) at various experimental conditions, i.