Photocatalytic Decomposition Of Acetaldehyde Research Articles

Impact of Erbium (Er) and Yttrium (Y) doping on BiVO4 crystal structure towards the enhancement of photoelectrochemical water splitting and photocatalytic performance

An efficient BiVO4nanocatalyst with Erbium (Er) and Yttrium (Y) doping was synthesized via a facile microwave irradiation route and the obtained materials were further characterized through various techniques such as p-XRD, FT-IR, FE-SEM, HR-TEM, UV–Vis DRS, PL, LSV, and EISanalysis. The obtained results revealed that the rare metals induce the stabilization of the monoclinic-tetragonal crystalline structure with a distinct morphology. The yttrium doped BiVO4 (Y–BiVO4) monoclinic-tetragonal exhibited anefficient photoelectrochemical water splitting and photocatalytic performanceare compared to bare BiVO4. TheY-BiVO4 indicated increased results of photocurrent of 0.43 mA/cm2and bare BiVO40.24 mA/cm2. Also, the Y-doped BiVO4 nanocatalyst showed the maximum photocatalytic activity for the degradation of MB, MO, and RhB. A maximum degradation of 93%, 85%, and 91% was achieved for MB, MO, and RhB respectively, within 180 min under the visible light illumination. The photocatalytic decomposition of acetaldehyde also was performed. The improved photoelectrochemical water splitting and photocatalytic activity are due to the narrowing the bandgap, leading to extending the photoabsorption capability and reducing the recombination rate of photoexcited electron-hole pairs through the formation inner energy state of the rare earth metals. The current study disclosed that the synthesis of nanomaterials with crystal modification could be a prospectivecontender forhydrogen energy production as well as to the photocatalytic degradation of organic pollutants.To the best of our knowledge, both photocatalytic and photoelectrochemical studies were never been reported before for this type of material.

Photocatalytic Decomposition of Acetaldehyde on Different TiO2-Based Materials: A Review

Purification of air from the organic contaminants by the photocatalytic process has been confirmed to be very perspective. Although many various photocatalysts have been prepared and studied so far, TiO2 is still the most commonly used, because of its advantageous properties such as non-toxicity, relatively low cost and high stability. Surface modifications of TiO2 were extensively proceeded in order to increase photocatalytic activity of the photocatalyst under both UV and visible light activations. The intention of this review paper was to summarize the scientific achievements devoted to developing of TiO2-based materials considered as photocatalysts for the photocatalytic degradation of acetaldehyde in air. Influence of the preparation and modification methods on the parameters of the resultant photocatalyst is reviewed and discussed in this work. Affinity of the photocatalyst surfaces towards adsorption of acetaldehyde will be described by taking into account its physicochemical parameters. Impact of the contact time of a pollutant with the photocatalyst surface is analyzed and discussed with respect to both the degradation rate and mineralization degree of the contaminant. Influence of the photocatalyst properties on the mechanism and yield of the photocatalytic reactions is discussed. New data related to the acetaldehyde decomposition on commercial TiO2 were added, which indicated the different mechanisms occurring on the anatase and rutile structures. Finally, possible applications of the materials revealing photocatalytic activity are presented with a special attention paid to the photocatalytic purification of air from Volatile Organic Compounds (VOCs).

Kinetic effects of polymorphs and surface areas on adsorption and photocatalytic decomposition of acetaldehyde on titania

Adsorption and photocatalytic decomposition behaviors of gas-phase acetaldehyde (CH3CHO), together with carbon dioxide (CO2) formation have been measured for pure titania (TiO2) powders with three types of polymorphs (anatase, brookite, and rutile) under UV-light illumination, and assessed by a kinetic model that takes into account the immediate decomposition of CH3CHO attached on the surface, and the gradual decomposition of CH3CHO adsorbed on the surface. Experimental data are well reproduced by the present model, highlighting how adsorption-related pathways markedly contribute to overall CH3CHO removal kinetics even for pure titanias. Although the initial removal rate depends on the surface area, which affects the adsorption capacity, it is suggested that specific surface area-based adsorbability and decomposition reactivity are enhanced by heightened crystallinity. Our kinetic analysis demonstrates that anatase exhibits the highest photocatalytic activity as a result of superior adsorbability, as well as superior decomposition reactivity, compared to other polymorphs.

Synthesis, Characterization and Photocatalytic Efficiency of ZnO/MWCNT Nanocomposites Prepared Under Different Solvent Conditions.

Here we report the application of zinc oxide (ZnO) coated multi-walled carbon nanotube (MWCNT) composites in the photocatalytic decomposition of acetaldehyde (AA). Zinc oxide nanoparticles were successfully coated on the multi-walled carbon nanotube via impregnation process using zinc acetate (Zn(CH₃COO)₂×2H₂O) as precursor and sodium dodecyl sulfate (SDS) treated multiwalled carbon nanotube as raw material under different solvent conditions. The applied solvents during preparation were ethanol (EtOH) and water (H₂O). As-prepared materials were characterized by thermal analysis (TG), X-ray diffraction (XRD), specific surface area measurement (BET) and transmission electron microscopy (TEM) techniques. Photocatalytic efficiencies of as-prepared composites were investigated in a stationary reactor equipped with UV lamp. Decomposition of acetaldehyde was followed by using gas chromatography (GC). Observations revealed that using impregnation method and different solvents the preparation of ZnO/MWCNT nanocomposites can be controlled easily. The highest degradation rate was achieved with the nanocomposite was synthetized using ethanol as solvent. The photocatalytic experiments revealed that the composite has higher photocatalytic activity than that of both the zinc oxide nanoparticles and the mechanical mixture of multi-walled carbon nanotube and zinc oxide.

Influence of an Electronic Structure of N-TiO2 on Its Photocatalytic Activity towards Decomposition of Acetaldehyde under UV and Fluorescent Lamps Irradiation

The electronic structure of N-TiO2 samples prepared by a sol-gel method was investigated by EPR (Electronic Paramagnetic Resonance) measurements and the energy-resolved distribution of electron traps. In EPR spectra, some of the resonance lines assigned to paramagnetic species of nitrogen and Ti3+ were detected. Sample prepared at 300 °C revealed the highest intensity line of the nitrogen paramagnetic centers, whereas that prepared at 400 °C showed a paramagnetic line for Ti3+. Measurements of the electron trap distribution showed higher density of electron traps for sample prepared at 400 °C than that at 300 °C. Sample prepared at 300 °C, which revealed the highest amount of nitrogen built in the titania in the interstitial position was the most active under visible light. It was evidenced that photocatalytic decomposition of acetaldehyde was dependent strongly on the BET surface area and electrokinetic potential of the photocatalyst surface. The UV content in the fluorescent lamp affected the yield of acetaldehyde decomposition.

Visible-Light Active Thin-Film WO3 Photocatalyst Crystallized By Post-Annealing in Air

Photocatalysts with visible light activity have been widely studied in recent years. We have reported on WO3 films as the high-performance visible-light active photocatalyst [1,2]. These films were deposited by dc magnetron sputtering on heated fused silica substrates at 800 oC. It must be preferable for the industrial application that the substrate temperature during the deposition should be lower for the window coatings for automobiles and architectures. In this study, the effect of post-annealing in air and total gas pressure during the deposition were studied. In addition, the loading effects of Pt nanoparticles on the WO3 film surface were also studied for the improvement of the photocatalytic activity. The WO3 thin films were deposited on unheated fused silica glass substrates by dc magnetron reactive sputtering using a W metal target, and with Ar and O2 as the sputtering and reactive gases, respectively. Post-annealing temperature was varied from 300 to 800 oC for the films sputter deposited at total gas pressure of 5.0 Pa. Furthermore, total gas pressure during the deposition was varied from 1.0 to 9.0 Pa. After the post-annealing at 400 or 600 oC, Pt nanoparticles were deposited on the WO3 film surface also by sputtering for 0, 7 or 40 sec. The surface coverage of Pt on the WO3 films were estimated by X-ray photoelectron spectroscopy. The Photocatalytic decomposition of acetaldehyde (CH3CHO) on the Pt/WO3 films was evaluated by the decrease in the concentration in the quartz cell. The visible light source was a Xe lamp with a 410-500 nm band pass filter (1.0 mW/cm2 at the film surface). Figure shows the photocatalytic decomposition for the WO3 films loaded by the Pt nanoparticles under visible light irradiation. It was found that the potocatalytic activities of the films crystallized by post-annealing（400 oC）was superior to the films deposited on the heating substrate at 800 oC, which was enhanced by the Pt loadings. [1] M. Kikuchi, Y. Shigesato, et al., of the 21st IUPAC SYMPOSIUM (2006) 496. [2] M. Imai, N. Oka, Y. Shigesato, et al., J. Vac. Sci. Technol. A 30, 031503-1-031503-5 (2012). [3] N. Oka, Y. Shigesato, et al., APL Materials 3, 104407-1-104407-6 (2015). [4] N. Oka, Y. Shigesato, et al., Jpn. J. Appl. Phys. 51, 055501-1-055501-5 (2012). Figure 1

Co-application of liquid phase plasma process for hydrogen production and degradation of acetaldehyde over Ni[sbnd]TiO2 supported on porous materials

Photocatalytic decomposition of acetaldehyde-contained wastewater was assessed for the degradation of pollutants and the production of hydrogen. Liquid phase plasma was applied in the photoreaction as a light source. The evolution of hydrogen and acetaldehyde degradation were characterized by the photocatalytic decomposition system. Ni-loaded TiO2 photocatalysts and various porous materials were introduced to the photocatalytic reaction. The photochemical decomposition by irradiation of the liquid phase plasma without photocatalysts produced some hydrogen evolution with the degradation of acetaldehyde, which was attributed to the decomposition of the reactant by active species generated by the irradiation of liquid phase plasma. The Ni loading on TiO2 brought out an enhancement of acetaldehyde degradation and hydrogen evolution. In the photocatalysis of acetaldehyde-contained wastewater using the liquid phase plasma, hydrogen evolution was accelerated due to the additional hydrogen production by the photocatalytic decomposition of acetaldehyde. The porous materials could be used as an effective photocatalytic support. MCM-41 mesoporous material has acted as a highly efficient photocatalytic support to the TiO2 photocatalyst.

Fabrication of Efficient Visible-light-responsive TiO2-WO3 Hollow Particle Photocatalyst by Electrospray Method

A visible-light-responsive TiO2-WO3 hollow particle photocatalyst was successfully fabricated by an electrospray method, followed by hydrothermal treatment and calcination at 873 K. The photocatalytic decomposition of acetaldehyde with pristine TiO2 and TiO2-WO3 hollow particles was evaluated under visible light irradiation (λ > 400 nm). The decomposition of acetaldehyde did not proceed readily with hollow TiO2 particles under visible light irradiation, whereas the hollow TiO2-WO3 particles showed high photocatalytic activity for the decomposition of acetaldehyde.

Influence of TiO2 hydrophilicity on the photocatalytic decomposition of gaseous acetaldehyde in a circulated flow reactor

The raw titania pulp was heated from 350 up to 700 °C and the impact of TiO2 properties on the photocatalytic decomposition of acetaldehyde under UV–Vis light was investigated. The physico-chemical parameters such as BET surface area, extent of surface hydroxylation, phase composition and size of TiO2 crystallites, were measured. It appeared that low-hydroxylated TiO2 prepared at 400 °C with relatively high BET surface area (106 m2/g) and the crystallized anatase phase was the most active for the acetaldehyde decomposition. High hydroxylation of TiO2 surface and the presence of amorphous TiO2 slowed down the photocatalytic process in the gas phase. On the other hand, high concentration of OH groups on TiO2 surface favored the generation of a high amount of OH radicals in an aqueous environment under UV irradiation. A sufficient amount of hydroxyl groups adsorbed on TiO2 surface is needed to facilitate electron–hole separation and OH radicals formation. On the other hand, an excessive content of these groups results in the creation of a barrier for adsorption of acetaldehyde and thus deteriorates photocatalytic process. Additionally, the high concentration of hydroxyl groups on TiO2 surface could accelerate recombination of radicals and reduce its photocatalytic efficiency in the gas phase.

Nitrification of Nb-Modified Titanias Prepared by the Solvothermal Method and their Photocatalytic Activities under Visible-Light Irradiation

Niobium modified titania samples were prepared by thermal reaction of titanium tetraisopropoxide and niobium pentaethoxide in 1,4-butanediol at 300 °C (solvothermal method), and the products were nitrified in an NH3 flow at 600 °C. The physicochemical property of the thus-obtained N-and Nb-co-doped titanias and visible-light response photocatalytic activity of FeOx-loaded N-and Nb-co-doped titanias were investigated. The N-and Nb-co-doped titanias had larger absorptions in the visible-light range as compared to the only N-doped titania samples. In ESR spectra of the Nb-modified TiO2 samples annealed at 300 °C after the nitrification, signals due to Ti3+ and oxygen vacancies, which accelerate the recombination of the photo-generated electrons and holes, were clearly observed. On the other hand, for the N-and Nb-co-doped titanias annealed at 500 °C, the signals due to Ti3+ and oxygen vacancies decreased significantly. Actually, the FeOx-loaded N-and Nb-co-doped samples annealed at 500 °C exhibited a higher photocatalytic activity for a photocatalytic decomposition of acetaldehyde under visible-light irradiation.

Sol-Gel Preparation, Characterization and Photocatalytic Activity of Nanostructured TiO2 Nanoparticles

ABSTRACTTo establish a promising method for the purification of air containing volatile organic compounds, TiO2 nanoparticles with interesting physicochemical properties were prepared by the sol-gel method to perform the photocatalytic decomposition of acetaldehyde. The obtained samples were characterized by the x-ray diffraction -Rietveld refinement, transmission electron microscopy (TEM) and the Brunauer, Emmet and Teller (BET) model. According to the results, the sample that presented the highest activity (96.4%) in the photocatalytic oxidation of acetaldehyde was the one annealed at 200 °C. This material showed the presence of a mixture of the anatase (higher proportion) and brookite phases, nanometric crystal size (7.03 nm) and high surface area (189 m2g-1). The physicochemical properties present in the TiO2-P-200°C nanoparticles suggest that they may establish a photoassisted reaction process for air purification, in which volatile organic compounds are photocatalitically decomposed.

Surface structure and visible light photocatalytic activity of titanium–calcium hydroxyapatite modified with Cr(III)

Abstract The synthetic titanium–calcium hydroxyapatite (Ti–CaHap) particles were treated with different concentrations of aqueous Cr(NO 3 ) 3 ·9H 2 O solution and the materials obtained were characterized by a variety of conventional techniques. The crystal structure and particle morphology of Ti–CaHap were essentially not altered by treating with Cr(III) solution. With increasing the Cr(III) concentration, the amount of Cr(III) in the products was increased and that of Ca(II) was decreased. XPS results revealed that the surface state of Cr of Ti–CaHap was trivalent. These facts allow us to infer that the Cr(III) was doped by substitution of surface Ca(II) of Ti–CaHap. Besides, IR results proved that increasing the Cr(III) concentration developed the surface Cr–OH band while the surface Ti–OH and P–OH bands of Ti–CaHap vanished. This imply that the formation of surface P–O-Cr(OH) 2 and Ti–O–Cr(OH) 2 groups, resulting the Cr(OH) 3 -like layer on the surface of Ti–CaHap particles. The Cr(III)-doped Ti–CaHap possessed the absorption peaks at 446 and 623 nm in vis range in addition to the UV absorption of charge transfer transition of O 2− → Ti 4+ . The vis absorption peaks developed on raising the Cr(III) concentration. The photocatalytic decomposition of acetaldehyde into CO 2 over Cr(III)-doped Ti–CaHap was detected under vis irradiation and the activity was lowered by the formation of Cr(OH) 3 -like layer on the particle surface.

Efficient Visible Light Active CaFe2O4/WO3 Based Composite Photocatalysts: Effect of Interfacial Modification

We report on the photocatalytic decomposition of acetaldehyde over CaFe2O4 (CFO)/WO3 based composite photocatalysts under visible light irradiation, emphasizing the photocatalyst composition optimization and the effect of interface modification on photocatalytic activity. Although heat treatment caused deactivation of CFO/WO3 composite photocatalyst, the photocatalytic activity of WO3 was improved by simply mixing with CFO, and 5 wt % CFO coupled WO3 showed the optimized performance. Ag and ITO coating on the CFO particle surface obviously promoted the photocatalytic activity of the CFO/WO3 composite. The CFO/Ag (or ITO)/WO3 composite photocatalyst could completely decompose acetaldehyde under visible light irradiation. X-ray photoelectron spectra suggested that the photoinduced self-reduction in WO3 was effectively suppressed after coupling with CFO. The possible mechanism of the surface modification effects was discussed.

Fabrication of Gold-Doped Titanium Dioxide (Tio2:Au) Nanofibers Photocatalyst by Vacuum Ion Sputter Coating

Gold-doped titanium dioxide (TiO2:Au) nanofibers were prepared by a combination of an electrospinning method and sputtering technology and characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that the morphologies of Au-deposited TiO2 nanofibers can be well controlled by the sputtering time. The photocatalytic decomposition of acetaldehyde on TiO2:Au nanofibers was investigated at room temperature. The photocatalytic effect of the TiO2 nanofiber was improved by using the Au-doped titania nanofibers catalyst and increased as the Au depositing time was increased from 40 s to 3 min. The photocatalytic removal rate of acetaldehyde remained above 94% on the TiO2:Au nanofibers (2 min) catalyst under ultraviolet (UV) irradiation for 70 min, 1.7 times that of pure TiO2 fibers.

Surface Functionalization of Electrospun TiO2Nanofibers by Au Sputter Coating for Photocatalytic Applications

Au-doped titania (TiO2:Au) nanofibers were prepared by a combination of the electrospinning method and sputtering technology. The results show that the morphologies of Au-deposited TiO2 nanofibers can be well controlled by the sputtering time. The photocatalytic decomposition of acetaldehyde on the TiO2:Au nanofibers was investigated at room temperature. Compared with pure TiO2 nanofibers, the TiO2:Au nanofibers exhibited higher photocatalytic activities.

High rate deposition of photocatalytic TiO2 films with high activity by hollow cathode gas-flow sputtering method

Photocatalytic TiO2 films were deposited by a hollow cathode gas-flow sputtering method using two Ti metal targets mounted parallel to each other. The Ar and O2 flow rates were 3000 and 0–50SCCM (SCCM denotes cubic centimeter per minute at STP), respectively, and total gas pressure during the deposition was maintained at 45Pa. The highest deposition rate for the photocatalytic TiO2 films was 162nm∕min at 30SCCM of O2 flow. The as-deposited films and postannealed films, annealed in air at 300°C for 1h, were used to carry out photocatalytic decomposition of acetaldehyde (CH3CHO). In particular, the postannealed films showed extremely high photocatalytic activity compared to the photocatalytic activity of films deposited by conventional reactive sputtering.

Analysis of Polymorphic Nanocrystals of TiO2 by X‐Ray Rietveld Refinement and High‐Resolution Transmission Electron Microscopy: Acetaldehyde Decomposition

In this work, TiO2 nanocrystals were synthesized by the sol‐gel method. These materials were annealed at 200 and 500∘C; and characterized by the XRD‐Rietveld refinement; and by BET and TEM. As for the low‐temperature‐treated sample (200∘C), nanocrystals with small crystallite sizes (7 nm) and high abundance of anatase, coexisting with the brookite phase, were obtained. Meanwhile, the sample annealed at 500∘C showed an increased crystallite size (22 nm) and an important polymorphic increment. The sample annealed at 200∘C showed a high activity in the photocatalytic decomposition of acetaldehyde.

Synthesis of alumina–titania solid solution by sol–gel method

Aluminum–titanium mixed metal oxides with various compositions were synthesized by sol–gel method and the photocatalytic activities for acetaldehyde decomposition were investigated. A mixture of aluminum isopropoxide and titanium butoxide in isopropanol was used as a precursor, and composition was controlled by varying relative concentration of each precursor in a mixture. X-ray diffraction analysis and Raman spectroscopy were employed to examine crystalline structure and surface area of synthesized samples was determined by BET method. Although structure transformation from anatase to rutile phase was observed for all synthesized samples, the transformation temperature was found to depend on sample composition (Al/Ti ratio). Photocatalytic decomposition of acetaldehyde was carried out in a closed borosilicate reactor under visible light illumination. The photocatalytic activity was measured with respect to composition and it was found to be strongly dependent on sample composition. Aluminum–titanium mixed oxides showed higher photocatalytic activity for acetaldehyde decomposition than either pure titania or pure alumina.

Effect of the addition of a small amount of vanadium on the photocatalytic activities of N- and Si- co-doped titanias under visible-light irradiation

Si-doped titanias with a Si/Ti charged ratio of 0.2 was prepared by thermal reactions of titanium tetraisopropoxide and tetraethyl orthosilicate in 1,4-butanediol at 300 °C (glycothermal reaction) and N- and Si- co-doped titanias were prepared by heating the thus-obtained Si-doped titanias in an NH3 flow. N- and Si- co-doped titanias had a stronger absorption in a visible light region of 400–550 nm, and exhibited high photocatalytic activities for decomposition of acetaldehyde under visible-light irradiation. In this study, N- and Si- co-doped titanias were further modified with vanadium by an impregnation method using an ammonium vanadate solution, and the obtained catalysts were characterized by XRD, BET surface area measurement, UV-vis, and ESR. Photocatalytic decomposition of acetaldehyde using the V-loaded N- and Si- co-doped titanias was examined and it was demonstrated that a very small amount of V-loading (V/Ti = 0.0001–0.001) significantly enhanced the photocatalytic activity under visible-light irradiation.

Photocatalytic activities and mechanism of the supercritically treated TiO2-activated carbon composites on decomposition of acetaldehyde

The supercritically treated TiO2-activated carbon (Sc-TiO2-AC) composites were studied for their adsorption and subsequent photocatalytic activities for acetaldehyde. Sc-TiO2-AC composites showed much higher decomposing ability for acetaldehyde compared to a noncomposite comprising a simple mixture of activated carbon and TiO2. This indicates that Sc-TiO2-AC composites have a synergetic effect of adsorption and photocatalytic decomposition of acetaldehyde. Meanwhile, acetaldehyde was found to be decomposed to CO2 as final product by Sc-TiO2-AC composites through the conversion to methanol, formaldehyde and acetic acid as intermediates. It was also found that many OH groups exist on the Sc-TiO2-AC composites. These OH groups can be assumed to take part in the photocatalytic degradation of acetaldehyde.