UV Light Photocatalytic Activity Research Articles

A eco-friendly, low cost green synthesis of Ag@Sm2O3/rGO nanocomposites with enhanced UV light photocatalytic and antimicrobial activity

In this research, we investigated the potential of a leaf extract from the Punica Granatum peel as a reducing and capping agent in the manufacture of a nanocomposite consisting of Ag-doped Sm2O3 nanoparticles encased in reduced graphene oxide (rGO). XRD, SEM, TEM, FTIR, XPS, PL, and DRS were all used to confirm the performance and characterisation of nanocomposite materials. Photocatalytic degradation studies of 4-nitrophenol (4-NP) and methylene blue (MB) provided interesting insights into the photocatalytic activity of Ag@Sm2O3/rGO. The results show that Ag@Sm2O3 particles between 10 nm and 20 nm in size are uniformly distributed across the RGO surface. Maximum photodegradation efficiency towards MB (96.7 %), high apparent constant (0.8716 min−1), and long-term stability under UV light exposure are all achieved when rGO is combined with Ag@Sm2O3 as the photocatalyst. It was confirmed that certain types of bacteria and fungi responded differently to the antibacterial properties of doped and undoped nanoparticles. The surface surface plasmon resonance (SPR) of Ag NPs had a role in the relationship between Sm2O3 nanoparticles and rGO sheets, which led to this finding. A novel Sm2O3-based photocatalyst with high solar absorption and higher catalytic activity is proposed, and a viable mechanism for developing such a material is shown in this study.

Europium decorated hierarchical TiO2 heterojunction nanostructure with enhanced UV light photocatalytic activity for degradation of toxic industrial effluent

Europium (Eu) doped cetyltrimethylammonium bromide (CTAB) surfactant assisted hierarchical TiO2 heterojunction nanostructure was synthesized by solvothermal method with ethanol as a solvent. The prepared nanostructure was subjected to various characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive spectrum (EDS) and Ultraviolet – diffuse reflectance spectroscopy (UV -DRS). The anatase phase of titania with its highly crystalline nature is confirmed by the XRD pattern. Crystallite sizes range from 4 to 10 nm according to XRD peak estimates. TEM and HRTEM studies are used to examine the prepared samples particle size and morphology. The elemental composition of the Europium (Eu) doped CTAB assisted TiO2 heterojunction nanostructure along with their corresponding band gap was estimated by EDS and UV-DRS studies respectively. The bandgap of the samples evaluated by UV–Visible spectroscopy are 3.40, 3.41 and 3.43 eV. The photocatalytic test was conducted in the presence of UV light and the amount of Congo red dye degradation increased with the time in the presence of the catalyst. After 75 min, it was discovered that the photocatalytic degradation efficiency was 97%. The photocatalytic effect depends heavily on the dispersion of the dopants.

A 2D pillared-bilayer iron-based metal–organic framework: syntheses, crystal structure, UV-light photocatalytic and heterogeneous Fenton-like catalytic activities

A 2D pillared-bilayer iron-based metal–organic framework: syntheses, crystal structure, UV-light photocatalytic and heterogeneous Fenton-like catalytic activities

Graphene Bridge for Photocatalytic Hydrogen Evolution with Gold Nanocluster Co-Catalysts.

Herein, the UV light photocatalytic activity of an Au101NC-AlSrTiO3-rGO nanocomposite comprising 1 wt% rGO, 0.05 wt% Au101(PPh3)21Cl5 (Au101NC), and AlSrTiO3 evaluated for H2 production. The synthesis of Au101NC-AlSrTiO3-rGO nanocomposite followed two distinct routes: (1) Au101NC was first mixed with AlSrTiO3 followed by the addition of rGO (Au101NC-AlSrTiO3:rGO) and (2) Au101NC was first mixed with rGO followed by the addition of AlSrTiO3 (Au101NC-rGO:AlSrTiO3). Both prepared samples were annealed in air at 210 °C for 15 min. Inductively coupled plasma mass spectrometry and high-resolution scanning transmission electron microscopy showed that the Au101NC adhered almost exclusively to the rGO in the nanocomposite and maintained a size less than 2 nm. Under UV light irradiation, the Au101NC-AlSrTiO3:rGO nanocomposite produced H2 at a rate 12 times greater than Au101NC-AlSrTiO3 and 64 times greater than AlSrTiO3. The enhanced photocatalytic activity is attributed to the small particle size and high loading of Au101NC, which is achieved by non-covalent binding to rGO. These results show that significant improvements can be made to AlSrTiO3-based photocatalysts that use cluster co-catalysts by the addition of rGO as an electron mediator to achieve high cluster loading and limited agglomeration of the clusters.

Facile Synthesis with TiO2 Xerogel and Urea Enhanced Aniline Aerofloat Degradation Performance of Direct Z-Scheme Heterojunction TiO2/g-C3N4 Composite.

Different TiO2/g-C3N4 (TCN) composites were synthesized by a simple pyrolysis method with TiO2 xerogel and urea. The structure and physicochemical properties of TCN were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, ultraviolet-visible diffuse reflectance spectrum, X-ray photoelectron spectroscopy, N2-adsorption isotherms and electrochemical impedance spectroscopy. Aniline Aerofloat was chosen as a typical degradation-resistant contaminant to investigate the photodegradation activity of TCN under UV irradiation. The results indicated that TCN had higher light absorption intensity, larger specific surface area and smaller particle size compared to pure TiO2. Furthermore, TCN had great recycling photocatalytic stability for the photodegradation of Aniline Aerofloat. The photocatalytic activity depends on the synergistic reaction between holes (h+) and hydroxyl radicals (·OH). Meanwhile, the direct Z-scheme heterojunction structure of TiO2 and g-C3N4 postpones the recombination of h+ and electrons to enhance UV-light photocatalytic activity.

Improving UV Light Photocatalytic Activity of WO3 by Doping with Boron and Compounding with Polypyrrole

Tungsten oxide (WO3) and boron-doped WO3 (WO3-B) nanoparticles were synthesized using the co-precipitation technique. In addition, as-prepared photocatalysts were compounded with a conducting polymer, polypyrrole (PPy), to prepare PPy/WO3 and PPy/WO3-B composites. The photocatalytic activity of pure WO3, WO3-B, and the PPy composites for decomposing an organic dye, methylene blue, was compared. Doping with boron atoms and/or compounding with polypyrrole improved the photocatalytic performance of WO3, which was probed by performing UV-Vis absorption spectroscopy. The boron doping improved the photocatalytic performance of the WO3 nanoparticles, which was ascribed to reducing the recombination rate of the photoinduced charge carriers and the increase in the number of photogenerated holes on WO3 upon UV light irradiation. Compounding WO3 with polypyrrole enhanced the photocatalytic activity, which was also assigned to the decrease in the recombination rate of the photoexcited charge carriers.

A facile synthesis of TiO2/BiOCl and TiO2/BiOCl/La2O3 heterostructure photocatalyst for enhanced charge separation efficiency with improved UV-light catalytic activity towards Rhodamine B and Reactive Yellow 86

A novel three-step synthesis approach of TiO2/BiOCl/La2O3 heterostructures was successfully prepared by hydrothermal, co-precipitation and solid-state reaction for enhances the photocatalytic activity through the degradation of Rhodamine B (RhB) and Reactive Yellow 86 (RY 86) organic dyes under UV-light illumination. The as-prepared photocatalysts were studied by using various physicochemical characterization tools like Powder X-ray diffraction (PXRD), UV–visible diffused reflectance spectroscopy (UV–Vis DRS), and Field emission scanning electron microscopy (FE-SEM) with EDX color mapping. The photocatalytic results were revealed TiO2/BiOCl and TiO2/BiOCl/La2O3 nanocatalyst effectively degrade RhB and RY 86 dyes molecules under UV light illumination within 120 min irradiation compare to pure TiO2. This prominent enhancement of UV-light photocatalytic activity can be ascribed to the efficient separation of photogenerated charge carriers by the effective construction of TiO2/BiOCl/La2O3 heterojunction.

Enhancement of photocatalytic activity using ternary Au@Pt-TiO2/nano-GO heterojunction for environmental remediation and clean energy production

In the present study, an attempt has been made to design ternary multifunctional nanocomposite photocatalyst based on Au@Pt-TiO2 core–shell nanoparticles anchored onto nano-graphene oxide (nano-GO) through facile one-pot solvothermal process. Evaluation of UV and visible light photocatalytic activities against MB dye and diuron pesticide decomposition, demonstrated a remarkable enhancement in photocatalytic performances, which indicates their potential as powerful photocatalyst. The enhancement of the photocatalytic activity of the designed ternary Au@Pt-TiO2/nano-GO could be attributed to the heterojunction structure and to the enhanced charge separation and light absorption of nano-GO and Au, Pt NPs. Before application, the ternary Au@Pt-TiO2/nano-GO photocatalyst was fully characterised (structural, morphology and composition) using powerful instruments including x-ray diffraction powder (XRD), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM). The optical response was investigated using UV-Visible spectrophotometer. The ternary Au@Pt-TiO2/nano-GO photocatalyst exhibits high crystallinity and high purity with uniform behaviour on size and shape. The hybrid Au@Pt-TiO2 nanoparticles were found to be well dispersed on nano-GO surface, which make this heterojunction very efficient for photocatalytic applications.

Impact of the stacking fault and surface defects states of colloidal CdSe nanocrystals on the removal of reactive black 5

The photodegradation of the reactive black 5 (RB5) with CdSe-MSA nanocrystals (NCs) synthesized by using mercaptosuccinic acid (MSA) was studied. The quantum confinement effect was confirmed via the blue shift of absorbance band and higher energy band gap values. Photoluminescence (PL) emissions were riddled with low energy bands arising from the recombination of trapped charge carriers. The surface stress of the nanocrystals from the ligand capped surface and the atomic position relaxation at the stacking fault interface was linked to an observed hexagonal distortion. The comparison of SO and LO modes was used to analyze the quality of NCs, defect and disorder on the NCs surface. Contact time and RB5 degradation with NCs were investigated to understand the adsorption-photocatalysis synergy. Statistical physics parameters were calculated to explain the dye adsorption on tested nanocrystals. CdSe-MSA showed remarkable UV-light photocatalytic activity with a dye degradation of 89% in 120 min.

Template-free assembly of protonated g-C3N4 nanosheets into microspheres with enhanced UV-light photocatalytic activity

Microspheres composed of H2SO4-protonated graphitic carbon nitride (g-C3N4) nanosheets were prepared through a template-free dialysis method. The g-C3N4 microspheres displayed a much larger band gap and greater UV light absorption in the light region of 200–300 nm compared with that of bulk g-C3N4, and thus substantially improved their UV light photocatalytic performance towards the degradation of Rhodamine B (RhB). The present work approached soft solution assembly of g-C3N4 nanosheets in a one pot manner, demonstrating a new strategy for constructing g-C3N4 nanostructures.

Efficient UV-light photocatalytic activity of TiO2@Phosphogypsum composite synthesized by sol–gel method

There is no doubt that novel and efficient photocatalyst with excellent properties based on TiO2 are highly desirable for practical applications to degrade high-concentration pollutants. Until now TiO2 nanoparticles have been successfully coupled with phosphogypsum prepared via a simple sol–gel method after calcination at different temperatures. The efficiency of the photocatalytic activity of composite can be explained by the difference of calcination temperatures in the structure of TiO2. Structures, morphologies, and surface areas were examined in all samples using specific characterization methods. In this process, the anatase and rutile structure of TiO2 nanoparticles were determined. The results obtained showed that the forms of the composite are spherical, although some nanoparticles are agglomerated. Surface area analyses showed that higher surface areas were obtained when the composite calcinated at 450 °C. We can attribute this to the small size of the particles. This study demonstrates that the synthesized composite display excellent photo-activity for degrading nitrate from aqueous solution up to 93.5% after 180 min of UV light irradiation time. Hence, we demonstrate a simple and efficient method to valorize phosphogypsum and to prepare a promising composite photocatalyst for reduction of nitrate in water and wastewater treatment process.

Carbon Black-Doped Anatase TiO2 Nanorods for Solar Light-Induced Photocatalytic Degradation of Methylene Blue.

In this work, C-doped TiO2 nanorods were synthesized through doping carbon black into hydrothermally synthesized solid-state TiO2 nanowires (NWs) via calcination. The effects of carbon content on the morphology, phase structure, crystal structure, and photocatalytic property under both UV and solar light by the degradation of methylene blue (MB) were explored. Besides, the photoelectrochemical property of C-TiO2 was systematically studied to illustrate the solar light degradation mechanism. After doping with C, TiO2 NWs were reduced into nanorods and the surface became rough with dispersed particles. Results showed that C has successfully entered the TiO2 lattice, resulting in the lattice distortion, reduction of band gap, and the formation of C–Ti–O, which expands TiO2 to solar light activation. Comparing with P25 and anatase TiO2 NWs, doping with carbon black showed much higher UV light and solar light photocatalytic activity. The photocatalytic activity was characterized via the degradation of MB, showing that Kap was 0.0328 min–1 under solar light, while 0.1634 min–1 under UV irradiation. The main free radicals involved in methylene blue degradation are H+ and OH•–. Doping with carbon black led to the reduction of photocurrent in a long-term operation, while C-doping reduced the electron–hole recombination and enhanced the carrier migration.

Synthesis and Characterization of Active Carbon-Titanium Dioxide Composite

Activated carbon was synthesized from Iraqi date palm seeds by physical and chemical activation technique under optimized growth conditions that allow the production of long, well aligned, high-quality activated carbon. Titanium dioxide nanoparticles were prepared using a sol gel method. The activated carbon/TiO2 composites were prepared using simple evaporation and a drying process. The structural, morphological and chemical properties of the prepared activated carbon, TiO2 and activated carbon/TiO2 composite were investigated by X-ray diffraction, Fourier transformed infrared and scanning electron microscope. The photocatalytic activity of activated carbon/TiO2 composite with 10 % of activated carbon was studied and compared with TiO2. The UV light photocatalytic activity was also evaluated by the photocatalytic degradation of phenol in an aqueous solution.

Enhancement of visible and UV light photocatalytic activity of rGO-TiO2 nanocomposites: The effect of TiO2/Graphene oxide weight ratio

Abstract In this study, rGO − TiO 2 nanocomposites were prepared by means of a simple hydrothermal approach using TiO 2 powder and GO nanosheets as starting materials. The TiO 2 / GO weight ratio varied from 0.25 to 2 wt%. The prepared samples were characterized using AFM, SEM and TEM microscopy as well as XRD, EDX, Raman, FTIR and UV–Vis spectroscopies. BET and BJH measurements were also performed to obtain the specific surface area and pore diameter size of the synthesized samples. It was found that the samples with TiO 2 / GO weight ratio below one have high effective surface area about 124 g/m2 and pore size of 6 nm. Photocatalyst evaluation revealed that only 0.06 mg/ml of prepared composite degraded 90% of 20 ppm Methylene blue (MB) in 15 min under 50 mW / cm 2 UV light intensity. The linear kinetic rate constant (k) of the samples promoted from 22 × 10 − 3 min−1 for TiO 2 under UV exposure up to 153 × 10 − 3 min − 1 and 65 × 10 − 3 min − 1 for composites under UV and visible irradiation, respectively. More detailed analyses showed that the photocatalytic activity of samples obtained figure of merit below unity. To the best of our knowledge this seems to be an impressive result. Impedance spectroscopy analysis revealed that the enhancement of charge transfer in composites as well as high effective surface area and their mesoporous structure are mainly responsible for the significant enhancement of MB photodegradation. The reactive species trapping experiments were performed by a series of radical scavengers. On the basis of the experimental results, the electrons and superoxide ions species play the main role in degradation of MB.

Circumferential growth of zinc oxide nanostructure anchored over carbon fabric and its photocatalytic performance towards p-nitrophenol

In present study, zinc oxide (ZnO) nanostructure anchored on carbon fabric (CF) was prepared using a combinational techniques of RF magnetron sputtering and hydrothermal method. The sputter seeded CF aided for the circumferential growth of ZnO nanostructure and its structural and optical characterization evidencing the c-axis orientation with the band gap of, 3.21 eV. ZnO nanostructure anchored CF was subjected towards UV light photocatalytic activity of p-nitrophenol for 150 min and remarkably higher activity of 98% was observed with better retrieval and recyclability upto 5 cycles. Because of these conspicuous features, it can serve as an expedient hybrid platform for photocatalytic application, better than the benchmark acid treated ZnO/CF.

Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

With an increased focus on light energy to facilitate catalytic processes, photocatalysts have been intensively studied for a wide range of energy and environmental applications. In this report, we describe the use of chemically dehydrated leaves as sacrificial foam-like templates for the growth of monolithic macrostructured semiconducting zinc oxide and nickel or cobalt doped zinc oxide materials. The composition and structure of these templated zinc oxides were characterized using X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Optical properties were examined using solid-state UV–vis diffuse reflectance spectroscopy. The metal-doped ZnO materials have enhanced visible absorption and lower band gaps as compared to ZnO. The botanically templated ZnO materials retain the macroscopic cellular form of the leaf template with fused nanoparticle walls. Their UV photocatalytic oxidative abilities were investigated using methylene blue dye degradation in air. The leaf templated zinc oxides degrade ~85% of methylene blue dye with 30 min of UV illumination. Nickel and cobalt doped zinc oxides showed varying degrees of decreased UV and visible light photocatalytic activity, possibly due to metal-mediated charge recombination. The mild chemical dehydration process here allows complex soft botanical structures to be easily utilized for templating materials.

A facile method of preparing sandwich layered TiO2 in between montmorillonite sheets and its enhanced UV-light photocatalytic activity

The ultrafine dispersing and subsequent self-assembling process of montmorillonite (MMt) micro layers were controlled by pH switch to build sandwich-layer structure of TiO2 intercalated MMt. Different pH controlling processes were carried out during hydrothermal synthesis, and the as-prepared samples were characterized by XRD, SEM, TEM, XPS, FTIR, UV–vis spectra, nitrogen adsorption/desorption analysis, and photocatalytic activities. The FTIR and XRD results reveal that TiO2 is chemically combined with MMt layers by hydrothermal process, which hinders the grain growth and anatase-to-rutile phase transition of loaded TiO2 and the transition temperature is approximately 900 °C. The micro-morphology analysis shows that TiO2 nanoparticles could be successfully intercalated into MMt layers by special pH controlling process, resulting in the expansion of interplanar spacing of MMt and increased interface action between TiO2 nanocrystals and MMt sheets. The size of TiO2 intercalated in the MMt is approximately 15 nm, which is much smaller than blank TiO2. Furthermore, comparing with ordinary surface loaded TiO2, the TiO2 nanoparticles sandwiched in MMt layers display much higher UV-light photocatalytic degradation activity and reliable recycling stability to methyl orange (MO), due to more Ti3+ active sites and larger porous volume caused by intercalation. Differed from previous TiO2-MMt, which has directional arrangement and narrowed interlayer spacing of (001) faces of MMt, such novel pH controlling process gives full play to the advantage of clay sheets to build layered limited TiO2, and solves traditional drawbacks of MMt supporting materials such as light barrier and limited mass transfer efficiency in composed photocatalysts.

Facile Synthesis and Characterization of Al Doped Tin Ferrite: A Study on UV Light Photocatalytic Activity and Active Species for Degradation of Methyl Orange

A series of nanocrystalline powders of Al doped tin ferrite were synthesized using a facile citrate-precursor process to study photocatalytic activity under UV light radiations. The structures of synthesized compounds was studied by X-ray diffraction technique and are further characterized by thermo-gravimetric analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, UV–Visible diffuse reflectance spectroscopy, BET surface area and pore volume analysis. The results found that, all these compounds crystallized in lower tetragonal structure. The rate of degradation of anionic methyl orange was estimated spectro-photometrically from residual concentration in dyes with UV irradiation time. The degradation study showed that, dye undergoes degradation with UV light in presence of doped compounds, but the degradation rates get decreased at high content of Al in the system. Scavenging experiments indicated that h+ and O2−⋅ radicals are the predominant species principally responsible for dye degradation.

Promoting the interfacial H2-evolution reaction of metallic Ag by Ag2S cocatalyst: A case study of TiO2/Ag-Ag2S photocatalyst

Metallic Ag has been widely demonstrated to be an excellent oxygen-reduction cocatalyst to significantly improve the photocatalytic decomposition performance of various organic substances. However, as a H2-evolution cocatalyst, the improved photocatalytic performance by metallic Ag is quite limited due to its low H2-evolution rate. In this study, for the well-known TiO2/Ag photocatalyst, Ag2S as the efficient H2-evolution active sites was selectively loaded on the metallic Ag surface to greatly promote the interfacial H2-evolution reaction rate. In this case, the TiO2/Ag-Ag2S sample was synthesized by a two-step process including the simple photoinduced deposition of metallic Ag on the TiO2 surface and the following in situ sulfidation of partial Ag into Ag2S. Photocatalytic experimental results indicated that the TiO2/Ag-Ag2S(40uL) photocatalysts clearly exhibited a significantly higher UV-light photocatalytic H2-evolution activity (119.11 μmol h−1) than the pure TiO2, TiO2/Ag and TiO2/Ag2S photocatalysts by a factor of 51.8, 3.9 and 3.6 times, respectively. On the basis of the present results, a synergistic effect of dual electron-cocatalyst (metallic Ag and Ag2S) is proposed for the improved photocatalytic H2-evolution activity, namely, the Ag-nanoparticle cocatalyst can steadily capture and transfer the photogenerated electrons from TiO2 surface, while the Ag2S cocatalyst is considered to be the interfacial active sites to promote the rapid H2-evolution reaction. This research may provide new strategies for the development of highly efficient photocatalytic materials used in various fields.

Core-shell SrTiO3/graphene structure by chemical vapor deposition for enhanced photocatalytic performance

Direct growth of high quality graphene on the surface of SrTiO3 (STO) was realized through chemical vapor deposition (CVD), to construct few-layer ‘graphene shell’ on every STO nanoparticle. The STO/graphene composite shows significantly enhanced UV light photocatalytic activity compared with the STO/rGO reference. Mechanism analysis confirms the role of special core-shell structure and chemical bond (TiC) for rapid interfacial electron transfer and effective electron-hole separation.