Active O2 Species Research Articles

Unraveling the potential of sonochemically achieved DyMnO3/Dy2O3 nanocomposites as highly efficient visible-light-driven photocatalysts in decolorization of organic contamination

In the present day, the widespread presence of lingering contaminants in ecosystems has prompted scientists to develop novel semiconductor nanoarchitectures that assist in photocatalytic reactions mediated by visible light. As a result, we propose to prepare a series of Dy-Mn-O based nano-catalysts using a sonochemical approach utilizing various ionic phases of surfactants as structure-directing agents. In this study, X-ray diffraction (XRD) and Rietveld refinement techniques were used to explore the fundamental effects of surfactants on the compositional-structural features of the materials. In terms of morphological profiles, DyMnO3/Dy2O3 (DM) nanostructures fabricated with Triton X-80 as a structure-directing agent showed the best uniformity with an acceptable size range between 14.14 and 52.35 nm. In the visible-light-driven photocatalytic domain, these nanocomposites provide high responsiveness based on their optical band gap value of 2.0 eV. According to our findings, two individual factors affect dye activity, namely dye type and concentration, which is why a high decomposition efficiency of 78.8% was obtained for 10 ppm Acid violet (AV) using DyMnO3/Dy2O3 nanocomposites after 120 min of exposure to visible light. Furthermore, radical quenching test confirmation confirmed the mechanistic behind the degradation process. This indicates that active species of O2•− and •OH may play a significant role in photocatalysis. As a result of repeated processes over three consecutive cycles, binary DyMnO3/Dy2O3 nanocomposites had an efficiency of 64.4% in removing dyes from the environment, indicating their high stability.

Integrating Bi-containing metal–organic frameworks for enhancing their LED visible-light-driven photocatalytic activities towards Rhodamine dye

Tuning metal–organic framework (MOF) properties to enhance their catalytic activities has recently gained considerable attention. In this work, Bi(III) MOFs, including UU-200, CAU-17, and their integrated architecture, namely MIX-UCAU, were effectively prepared and characterized by various techniques, including FE-SEM, XRD, XPS, FT-IR, Raman, TGA, and EIS analyses. Results revealed that the UU-200 and CAU-17 frameworks were effectively integrated into a heterojunction MOF using a mixture of DMF and MeOH. The MIX-UCAU exhibited increased crystallinity, higher oxygen defect concentration and improved light absorption. The combined UU-200-CAU-17 framework also showed enhanced photo-generated electron-hole pairs separation and immigration performance compared to single MOFs. The photodegradation experiments of Rhodamine B dye (RhB) in an aqueous solution showed that the MIX-UCAU had a high photodegradation efficiency of ca. ∼ 99 % within 90 min under energy-saving visible LED light irradiation, surpassing the bare UU-200 (∼81 %) and CAU-17 (∼89 %). In addition, the catalyst showed good photostability under successive cyclic experiments. The LC/MS and radical quenching tests revealed the degradation of RhB, including several steps, including the N-dealkylation, decarboxylation, deamination, and ring cleavages to tiny fragmentation products, and these procedures were predominantly controlled by the active species of O2•– and h+. The study provides a facile and efficient strategy for developing photocatalysts for treating organic pollutants in wastewater.

Visible-light S-scheme heterojunction of copper bismuthate quantum dots decorated Titania-spindles for exceptional tetracycline degradation

The rational heterojunctions for antibiotics degradation have sparked significant attention in wastewater purification. In this study, we report a unique S-scheme photocatalytic system by in-situ growth of CuBi2O4 quantum dots (QDs) onto {101} facet of TiO2 spindles (TiO2-P) via hydrothermal transformation of Na-titanate nanotubes, which is observed by transmission electron microscopy technology. The CuBi2O4/TiO2-P effectively achieves photo-degradation of tetracycline (TC) using visible light (e.g. an 82% TC degradation efficiency at 60 min), which is attributed to the promotion of the charge separation and retaining strong redox capacity at the heterojunction interfaces via the active species of O2−, OH, and h+. Moreover, density functional theory (DFT) calculations show that a built-in electric field forms at the interface of the S-scheme heterojunction. In all, this work introduces a straightforward in-situ hydrothermal growth method to construct S-scheme photocatalysts for effective water treatment.

Robust chromophore-integrated MOFs as highly visible-white-light active and tunable size-selective photocatalysts towards benzothiazoles

Visible-light heterogeneous photocatalyst with high activity and selectivity is crucial for the development of organic transformations, but remains a formidable challenge. Herein, a simple and effective strategy was developed to integrate tetrazine moiety, a visible light active unit, into robust metal-organic frameworks (2D MOF-1(M), M = Co, Mn, Zn, and 3D MOF-2(Co)). MOF-1 series are isomorphous 2D porous frameworks, and MOF-2(Co) displays 3D porous framework. Interestingly, benefiting from the oxidative active species of O2•−, these MOFs all exhibit obviously highly enhanced photocatalytic activities toward the straightforward condensation of o-aminothiophenol and aromatic aldehydes at room temperature in EtOH under visible-white-light irradiation. Notably, compared to 3D MOF, the 2D layered MOF-1(Co) exhibited more excellent catalytic activity with a wide range of substrates possessing preeminent tolerance of steric hindrance. Most impressively, MOF-1(Co) can be recycled at least five times without significant loss of catalytic activity or crystallinity, exhibiting excellent stability and reusability. This study sheds light on the wide-ranging prospects of visible light active 2D MOFs as green photocatalysts for the preparation of fine chemicals

Photocatalytic activity of the visible-light-driven spherical Ag2S modifying the CdS synthesized by the facile chemical methods for the degradation of methylene blue and rhodamine B

Semiconductor photocatalyst is a simple, efficient, low-cost, and green solution for dealing with the environmental crisis. To suppress the recombination of electrons and holes and the photocorrosion of the CdS synthesized via a controllable chemical precipitation method without using any surfactants or templates, the CdS–Ag2S heterostructure was synthesized by a facile ion exchange technique. The CdS and CdS–Ag2S photocatalysts were characterized, and the results confirmed the formation of Ag2S particles on the surface of CdS spheres. Based on the optical properties of the CdS–Ag2S heterostructure compared with those of the pure CdS, investigated by ultraviolet–visible diffuse reflectance spectra (UV–Vis DRS) and photoluminescence (PL), the greater absorption capacity, narrower band gap (2.02 eV), and more efficient transfer and separation of charge carriers were observed. The value of the specific surface area of CdS–Ag2S (415.93 m2/g) was studied via the nitrogen adsorption and desorption isotherms. Accordingly, it is higher than the specific surface area of the bare CdS (33.385 m2/g) due to having more active sites. The photocatalytic activities of CdS and the CdS–Ag2S heterostructure were evaluated by the degradation of the dyes of methylene blue (MB) and rhodamine B (RhB), and the uncolored organic contaminant of phenol. The photodegradation of MB, RhB, and phenol by CdS increased from 80%, 67%, and 61%–98%, 90%, and 81% by CdS–Ag2S, respectively, within 180 min under the visible light irradiation. Furthermore, the CdS–Ag2S heterostructure exhibited a suitable stability after being used in three cycles. The efficiencies of sunlight and visible light irradiation for photodegradation of MB and RhB were compared. The effects of the initial concentration of the dyes, concentration of the catalyst, pH, and the presence of Cl− and CO32− ions (available in the wastewater containing dyes) on the photodegradation of MB and RhB by the CdS–Ag2S heterostructure were also investigated. The electrochemical impedance spectroscopy (EIS) measurement revealed that the CdS–Ag2S heterostructure accelerated the photogenerated transfer of charge carriers. The present work has recommended a new approach using the chemical precipitation and ion exchange to synthesize 3-dimensional CdS–Ag2S spheres with an excellent photocatalytic performance. A proper mechanism was suggested to investigate the photocatalytic process of the CdS–Ag2S heterostructure. Also, the radical trapping experiment was carried out via various scavengers to distinguish the role of the active species of O2•-, OH•, h+, and e−, respectively. Finally, the kinetics of the photodegradation of MB and RhB could be studied by Langmuir-Hinshelwood model explained as pseudo-first-order.

Heterogeneous activation of persulfate by Bi2MoO6–CuS composite for efficient degradation of orange II under visible light

Here in, a special catalytic system of potassium persulfate (K2S2O8, PS) activated by Bi2MoO6–CuS composite was established for the orange II (OII) degradation under visible light. The Bi2MoO6–CuS composite was synthesized by a two-step hydrothermal and solvothermal methods. The structure, morphology, light absorption and photocatalytic properties of the composite were respectively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible diffuse reflectance spectroscopy (UV–vis DRS). The removal efficiency of OII degradation in the Bi2MoO6–CuS/PS/vis system reached to 98% within 80 min, which was much higher than that of either Bi2MoO6 or CuS alone. A feasible mechanism analysis of OII degradation was proposed and validated by simple classical quenching experiments and electron spin resonance (ESR) spectroscopy. The high removal efficiency by the nanocomposite could be attributed to highly active species of O2·-, ·OH and SO4•− radicals in the Bi2MoO6–CuS photocatalytic oxidation system. Moreover, the composite material retained its activation performance even after 5 degradation cycles, which suggested its high stability.

Significant promotion of reducing treatment on Pd/TS-1 zeolite for formaldehyde catalytic purification at ambient temperature

This study was conducted to investigate the effect of reducing pretreatment on physicochemical properties of zeolite catalysts and their performances on formaldehyde (HCHO) oxidation at ambient temperature. Pd/TS-1(Fresh) was tailored by different reductive gases (H2, CO) and liquid agents [ascorbic acid (AA), ethylene glycol (EG), sodium borohydride (NaBH4)]. Based on the characterization of HRTEM and CO chemisorption, it was shown that the reducing treatment could significantly reduce the size of Pd nanoparticles (NPs) based on the good dispersion of noble metal. The smallest size of Pd nanoparticles with 5.1 nm was achieved by using NaBH4 as reducing agent. Accordingly, the best activity was observed on the Pd/TS-1(NaBH4) sample, pretreated by NaBH4 in aqueous solution, which could eliminate HCHO completely even at room temperature. Combined with Raman, H2-TPR, and CO-DRIFT, the excellent catalytic performance of Pd/TS-1(NaBH4) are mainly ascribed to the high Pd dispersion, superior redox properties and abundant active O2 species.

Highly efficient photocatalytic NO removal and in situ DRIFTS investigation on SrSn(OH)6

A novel SrSn(OH)6 photocatalyst with large plate and particle size were synthesized via a facile chemical precipitation method. The photocatalytic activity of the SrSn(OH)6 was evaluated by the removal of NO at ppb level under UV light irradiation. Based on the ESR measurements, SrSn(OH)6 photocatalyst was found to have the ability to generate the main active species of O2•−, •OH and 1O2 during the photocatalytic process. Moreover, SrSn(OH)6 photocatalyst not only exhibits high photocatalytic activity for NO removal (79.6%), but also has good stability after five cycles. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to investigate the NOx transfer pathway and the intermediate products distribution during the adsorption and photocatalytic NO oxidation process. The present work not only provides an efficient material for air pollutants purification at room temperature but also in-depth understanding of the mechanism involved in the photocatalytic NO removal process.

UV light decontamination and secondary pollution products of G-series chemical warfare model molecules contaminated on Mo and MoOx surfaces

Understanding decomposition mechanism and analysis of secondary products for a chemical warfare agent (CWA) simulant on a contaminated target area are very important for better treatments of contaminated primary and secondary pollutants, and the development of a decontamination method. Herein, UV light (lamp and 266-nm laser high power pulses) photodecomposition method was introduced for the decontamination of G-series dimethyl methylphosphonate, dimethyl phosphite, diethyl methylphosphonate, and diethyl phosphite CWA model molecules contaminated on Mo and MoOx surfaces under various conditions. The secondary gas products were fully examined by gas chromatography and mass spectrometry, and the surface residues were also examined by scanning electron microscopy, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy before and after UV decontamination. Density function theory was employed to calculate the bond dissociation energies of the major chemical bonds for the CWA simulants. The full database for the photodecontamination products, the decomposition mechanism, the bond energies, and the roles of active species of O2−, h+ or OH reported in the present study provide valuable information on the development of future remote UV laser CWA decontamination system.

The removal mechanism of nitrobenzene by the Cu-Fe/Carbon material under different aeration conditions

Zero-valent Cu-Fe bimetallic porous carbon materials were successfully applied to remediate organic wastewater. In this work, we successfully recycled the layered double hydroxides (LDHs) adsorbed with Orange II (OII) to form a zero-valent Cu-Fe bimetallic porous carbon material (CuFe/Carbon). The characterization results showed that CuFe/Carbon was a zero-valent Cu-Fe bimetallic porous graphene-like carbon material. In the course of the experiment, we found that aeration condition had a great influence on the activity of CuFe/Carbon. The removal efficiency of nitrobenzene (NB) was 100 % in nitrogen system and 48 % in air system. The active species of O2− and OH was formed under air condition, while there was no active species under nitrogen condition. NB was reduced to aniline directly under nitrogen condition. We proposed there were reduction and oxidation mechanisms under different aeration conditions. This work mainly investigated the conversion process of a novel material under different reaction conditions, which provided theoretical support for the removal of organic matters.

Towards efficient Pd/Mn3O4 catalyst with enhanced acidic sites and low temperature reducibility for Benzene abatement

The activity of supported Pd catalyst as a result of metal oxide support (zinc, titanium, copper and manganese) is explored in the abatement of C6H6 in the gas-phase. The high-activity and cost-effective catalysts were synthesized utilizing impregnation assisted biosynthesis (IB) method. NH3-TPD, XRD, H2-TPR, TEM, XPS, O2 and Benzene-TPD, SEM and in situ DRIFT were done to probe their physicochemical characteristics and predict the plausible oxidation mechanism. Pd particle size and dispersion, and support active acid sites were the determining factors for activity. These factors markedly affected the catalyst ability to generate surface active O2 species from the metal oxides lattice station and controlled the benzene absorption/desorption rates. The as-synthesized Pd/Mn3O4-O with small crystallite size, good Pd dispersion, improved acid sites, and low activation energy (Ea = 45.3 kJ/mol) showed commendable O2 transportability and activity as low as 140 °C, GHSV of 120,000 mLg−1 h−1. Its T100 at 240 °C was similar to Pd supported on TiO2 but was 20, 40 and 60 °C better than Pd/Mn3O4-C, Pd/ZnO and Pd/CuO. In situ DRIFT studies showed that the main intermediate species benzoquinone are oxidized to CO2 and H2O through the alkoxide and acid sites. Moreover, it was stable and highly resistant to H2O vapor.

Flame retardant and visible light-activated Fe-doped TiO2 thin films anchored to wood surfaces for the photocatalytic degradation of gaseous formaldehyde

Flame retardant and visible light-activated Fe-doped TiO2 thin films were anchored to wood surfaces by a facile precipitation method for the photocatalytic degradation of gaseous formaldehyde. All of the as-prepared TiO2 thin films exhibited the anatase crystal structure and grew on the wood surfaces by the aggregation of nanoparticles with diameters ranging from 11 to 16 nm. The UV–vis diffuse reflectance spectroscopy (UV–vis DRS) results showed that the presence of a small amount of iron ions in the TiO2 matrix could significantly extend the optical responses in the UV to visible region. Compared to the pure TiO2/wood samples, the Fe-doped TiO2/wood samples exhibited higher photocatalytic activities under visible light irradiation. The optimum nFe/nTi molar ratio was 2.0 at. %. The electron spin resonance (ESR) tests further confirmed that the active oxygen species of OH and O2– that were generated on the Fe-doped TiO2/wood samples under visible light irradiation are responsible for the degradation of formaldehyde. The Fe-doped TiO2 samples also exhibited high stability and reusability after 6 cycles. Additionally, the limiting oxygen index of the original wood increased from 24.8% to 33.9% after it was coated with Fe-doped TiO2 thin films, indicating a significant improvement in its flame resistance.

Ordered layered N-doped KTiNbO5/g-C3N4 heterojunction with enhanced visible light photocatalytic activity

A facile one-step calcination approach for the synthesis of ordered layered N-doped KTiNbO5/g-C3N4 (NTNO/CN) heterojunction composites was developed. It was found that KTiNbO5 layers were in-situ doped by nitrogen atoms to form N-KTiNbO5 and two-layered g-C3N4 nanosheets were formed within the interlayers of N-KTiNbO5 due to the space-confined effects. The photocatalytic performance of the resulted composites was evaluated by the degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation. N-KTiNbO5 coupled with a proper amount of g-C3N4 exhibited an excellent photocatalytic performance due to the synthetic effects of N doping and layered heterojunction, leading to the high efficiency of light harvesting and charge separation. Especially, the in-situ intercalated two-layered g-C3N4 nanosheets can significantly increase the contact area with N-KTiNbO5 layers for efficient charge transfer across the interface, showing a much greater effect on the enhanced photocatalytic activity than those on the pure surface of N-KTiNbO5. It is expected that such a layered heterojunction can greatly speed up the separation and efficient transfer of photogenerated charge carriers. The active species of O2− played a leading role in the photocatalytic process while h+ contributed to a lesser extent during the photocatalytic degradation of RhB over NTNO/CN-1, as determined by the active species capture experiment and ESR spectra. This work provides a new insight into the preparation of layered heterojunction hybrids with ordered alternative layered structure, and thus opens up the possibility of ‘design-and-build’ 2D layered heterojunctions for large-scale theoretical exploration and practical applications.

Synergistic Ag/TiO2-N photocatalytic system and its enhanced antibacterial activity towards Acinetobacter baumannii

The hybrid Ag/TiO2-N photocatalyst was prepared via a supercritical solvothermal process in ethanol fluid. The simultaneous achievement of reduction of Ag+ ions and N-doping in silver-ammonia complex solution led to the uniform distribution of Ag nanoparticles stably combined with the surface of TiO2-N substrate. As a result, the visible-light photocatalytic inactivation of Acinetobacter baumannii was facilitated via the enhanced visible light harvesting and the high separation efficiency of photo-induced charge carriers. By means of the main active species of O2− radical, the synergistic effect of Ag nanoparticles and TiO2-N could induce the structure change of bacteria with the leakage of K+ ions as well as the mineralization of cell membrane with the elimination of self-repair function, leading to the final cell death. In comparison, the bactericidal activity of Ag nanoparticles and TiO2-N under UV light irradiation was due to the intrinsic efficiency and the high light harvesting, respectively. The photothermal effect of Ag nanoparticles in the near-IR light region could be possibly remained by TiO2-N substrate to achieve the antibacterial activity. Furthermore, Ag/TiO2-N photocatalyst played great bactericidal effect for kinds of bacteria, implying the applicable future to the medical disinfection.

Using Iron-Manganese Co-Oxide Filter Film to Remove Ammonium from Surface Water.

An iron-manganese co-oxide filter film (MeOx) has been proven to be a good catalyst for the chemical catalytic oxidation of ammonium in groundwater. Compared with groundwater, surface water is generally used more widely and has characteristics that make ammonium removal more difficult. In this study, MeOx was used to remove ammonium from surface water. It indicated that the average ammonium removal efficiency of MeOx was greater than 90%, even though the water quality changed dramatically and the water temperature was reduced to about 6–8 °C. Then, through inactivating microorganisms, it showed that the removal capability of MeOx included both biological (accounted for about 41.05%) and chemical catalytic oxidation and chemical catalytic oxidation (accounted for about 58.95%). The investigation of the characterizations suggested that MeOx was formed by abiotic ways and the main elements on the surface of MeOx were distributed homogenously. The analysis of the catalytic oxidation process indicated that ammonia nitrogen may interact with MeOx as both ammonia molecules and ammonium ions and the active species of O2 were possibly •O and O2−.

Fabrication of a novel Z-scheme g-C3N4/Bi4O7 heterojunction photocatalyst with enhanced visible light-driven activity toward organic pollutants

In this work, highly efficient g-C3N4/Bi4O7 heterojunction photocatalysts have been successfully fabricated by a facile method. Compared with the bare photocatalysts, the obtained g-C3N4/Bi4O7 hybrid photocatalysts exhibited efficient degradation activity toward methylene blue (MB), phenol, rhodamine B (RhB), and bisphenol A (BPA) under visible light irradiation. The influences of different g-C3N4 contents on the photocatalytic efficiency of the hybrid photocatalysts have been investigated. The results revealed that the g-C3N4/Bi4O7 with g-C3N4 mass ratio of 30% exhibited the best photocatalytic activity. The activity enhancement should be ascribed to the improved visible light adsorption as well as the effective Z-scheme charge transfer according to the energy band theory. The UV–vis diffuse reflectance spectra (DRS) shows that the absorption edge of g-C3N4 move towards longer wavelength with the increment of Bi4O7 component. The strong connection between g-C3N4 and Bi4O7 was investigated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Subsequently, the effective Z-scheme charge transfer has also been verified by using transient photocurrent measurements and electrochemical impedance spectroscopy. Controlled experiments proved that active species of O2- and h+ were produced in the degradation system, which played the major role in the degradation of MB. A possible Z-scheme degradation mechanism over g-C3N4/Bi4O7 hybrid photocatalysts was proposed.

Facile synthesis of hierarchical ZnIn2S4/CdIn2S4 microspheres with enhanced visible light driven photocatalytic activity

Hierarchical ZnIn2S4/CdIn2S4 microspheres have been synthesized by a facile chemical co-precipitation method at low temperature. The obtained samples were characterized by XRD, SEM, XPS, and UV–vis DRS. The XRD patterns of ZnIn2S4/CdIn2S4 showed the distinctive peaks of both ZnIn2S4 and CdIn2S4. The obtained ZnIn2S4 microspheres were composed of numerous large nanoplates, while CdIn2S4 microspheres possessed a relatively smooth surface. As for ZnIn2S4/CdIn2S4 composites, it was observed that partial of the ZnIn2S4 nanoplates were grown on the surface of CdIn2S4 microspheres. The absorption edge of ZnIn2S4 move toward longer wavelengths with the increment of CdIn2S4 component. In the photocatalytic degradation of MO, the ZnIn2S4/CdIn2S4 (mole ratio=1:3) photocatalyst exhibited the best activity compared with pure ZnIn2S4 and CdIn2S4. The degradation ratio of MO (10ppm) was about 99.7% after 90min of reaction, while RhB (4×10−5M) could be completely degraded within 70min over ZnIn2S4/CdIn2S4. The activity enhancement can be ascribed to the improvement of visible light adsorption and separation efficiency enhancement of photo-generated carriers. Controlled experiments proved that active species of O2−, OH, and h+ were produced in the degradation system, which played the major role in the degradation process.

Synthesis and characterization of Ag3PO4/LaCoO3 nanocomposite with superior mineralization potential for bisphenol A degradation under visible light

Bisphenol A, an endocrine disruptor, is a kind of organic chemicals with various applications in the polymer industry that is proven to elicit endocrine disrupting effects. BPA is urgent for environmental remediation and human health, which has raised a great concern in seeking an ideal treatment method. Photocatalytic is a promising method to remove organic pollutants from water. Herein, in this study, novel visible-light-driven materials Ag3PO4/LaCoO3 with varying LaCoO3 content were prepared through the liquid deposition method for the first time, and its structures, morphologies, optical properties were detected by means of SEM, TEM, EDX, XRD, XPS, BET, UV-Vis and PL analyses. Moreover, the photocatalytic performance of Ag3PO4/LaCoO3 toward Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, abbreviated as BPA) degradation was investigated, and the as-prepared Ag3PO4/LaCoO3 exhibited the enhanced photocatalytic activity and stability than pure Ag3PO4 under visible light illumination. When the content of LaCoO3 was 10%, the BPA was completely degraded after the irradiation for 40 min, and 77.27% of the total organic (TOC) was removed. The kinetic analysis indicated that the degradation rate constant of BPA over the Ag3PO4/LaCoO3(10%) hybrid materials was 0.0831min−1, being 44.68 times that of LaCoO3, and 3.02 times that of Ag3PO4. In addition, four main intermediate were detected during the photocatalytic degradation. To analyze the photocatalytic degradation mechanism of BPA, particular attention was paid to the identification of active species and intermediates. the free radical trapping experiments revealed that all the active species of O2−, OH and h+ participated in the degradation of BPA. Furthermore, a photodegradation mechanism of BPA was proposed through the results of GC-MS, and the photocatalytic mechanism of Ag3PO4/LaCoO3 was also discussed.

Growth and characterization of Ta2O5 nanorod and WTa2O5 nanowire films on the tantalum substrates by a facile one-step hydrothermal method

Tungsten doped tantalum pentoxide (WTa2O5) nanostructured film has been successfully prepared via a facile eco-friendly one-step hydrothermal method on tantalum substrate. The synthesized sample was characterized by various techniques and its photo catalytic activity was investigated in methylene blue degradation under xenon light irradiation. Results indicated that the introduction of tungsten into Ta2O5 promoted the light absorption performance, which resulted in a high photo catalytic activity of WTa2O5 nanostructure. WTa2O5 sample showed a methylene blue degradation rate of 0.0085min−1 which was about 9 times higher than those of pure Ta2O5. The quenching effects of different scavengers demonstrate that the active species of O2-• and OH• play major roles in the whole photo degradation process of methylene blue. It is expected that this new WTa2O5 nanostructure may be a promising candidate for organic pollutant degradation.

Photo-assisted synthesis of Ag3PO4/reduced graphene oxide/Ag heterostructure photocatalyst with enhanced photocatalytic activity and stability under visible light

A novel Ag3PO4/reduced graphene oxide/Ag nanocrystals (Ag3PO4/RGO/Ag) heterostructure photocatalyst has been synthesized using a facile photo-assisted reduction method for the first time. The Ag3PO4/RGO/Ag that consists of close chemical bonding between RGO and Ag3PO4 nanoparticles as well as dispersive plasmonic Ag nanocrystals on the RGO sheets exhibited superior photocatalytic activity and stability to bare Ag3PO4, Ag/Ag3PO4 and Ag3PO4/GO in degradation of Rhodamine B and phenol under visible light. It is suggested that the photo-generated electrons in Ag3PO4 can be transferred to RGO/Ag, leading to efficient separation and transfer of electron–hole pairs. Meanwhile, under light irradiation, the plasmonic Ag nanocrystals also generate electron–hole pairs through surface plasmon resonance (SPR), in which the active electrons can facilitate the formation of additional active species of O2•− for photocatalysis whereas the holes can be filled by electrons from RGO. As a result, both the photocorrosion of Ag3PO4 and the recombination of electron–hole pairs are suppressed due to the special electron transfer route of Ag3PO4→RGO→Ag in the heterostructure. This work suggests that the reasonable combination of semiconductors and graphene decorated with noble metallic nanocrystals can provide a versatile strategy for the synthesis of high efficient heterostructed photocatalysts.