Activity In Photodecomposition Research Articles

Fruit Extract Mediated Formation of Luminescent Titanium Dioxide Nanometer-Sized Particles: An Innovative Strategy in Domain of Photodecomposition and Germicidal Properties.

Discoveries in nanotechnologies are placing a great deal of attention on greener strategies that use harmless substances and moderated reactions to promote healthy development. This work used a straightforward, innovative, and cost-effective sustainable approach to produce bio-augmented TiO2 nanometer-sized particles (NMSP) by applying a water-based extract of the star fruit as a stabilization and reduction agent. A variety of techniques, comprising UV-Vis, XRD, FT-IR, FE-SEM with EDAX, and TEM, have been employed to investigate the formed TiO2 NMSP. The germicidal properties of formed TiO2 NMSP towards germs have been investigated by implementing an agar-based pore plate technique. Congo red and methylene blue dyes have been applied to assess photodecomposition activity. The TiO2 NMSP exhibited significant germicidal efficacy versus many pathogenic microbes. The maximum degradation percentages of Congo red and methylene blue were 89.2% and 83.7%, achieved after 60 and 70 min, respectively. Consequently, it is determined that the selected NMSP composition enhanced germicidal and photodecomposition capabilities. The combined effort may serve as an effective method for eliminating color degradation concerning effluent and could potentially be employed in the field of medicine to address antibiotic resistance.

Fabrication of a peptide–AuNP–TiO2 nanocomposite and its application as a VOC sensor

We fabricated a volatile organic compound (VOC) sensor with a peptide–Au nanoparticle (AuNP)–TiO2 nanocomposite in which AuNPs were linked with TiO2-coated conductive peptide nanowires. The conductive peptide nanowires were formed between the AuNPs via self-assembly through the complexation of amphiphilic peptides, LESEHEKLKSKHKSKLKEHESEL, and Co(II). Furthermore, TiO2 mineralization on the surface of the peptide nanowires yielded mixed crystals of rutile and anatase, which exhibited highly effective photolytic activity. In particular, the obtained TiO2 exhibited three times greater photodecomposition activity in the unsintered state toward organic matter than did commercially available TiO2. Next, we constructed a VOC sensor by immobilizing peptide–AuNP–TiO2 nanocomposites on a comb electrode. The electrochemical properties of the nanocomposite changed drastically under light irradiation in the presence of VOCs, indicating transport of the VOC-decomposition-generated photoexcited electrons of TiO2 to AuNPs through conductive peptide nanowires, which prevented electron–hole recombination. The obtained sensor exhibited a sensing range of 2–100 ppm for dichloromethane, which was used as a representative VOC. Therefore, nanocomposites made of AuNPs linked with conductive TiO2 nanotubes may be highly effective for TiO2-driven VOC decomposition. Moreover, we believe that this nanocomposite has high sensitivity for sensing VOCs.

A review on the inference of doping TiO2 with metals/non-metals to improve its photocatalytic activities

The band-gap energy of TiO2 nanoparticles has been modified using different methods. The study reviewed the effects of doping and co-doing TiO2 nanotubes with different metals and nonmetals to modify its band gap and improves the photocatalytic activity of the nanoparticles. From our findings reviewing different articles, co-doing TiO2 using dissimilar metal ions like Cerium (Ce) together with nitrogen (N) ions or chromium (Cr) and iron (Fe) ions will decrease particle size, broaden the area of the surface, and as well modifies the particle’s band-gap for visible light to energize an electron causing its movement from the valance band to the conduction band. The studies also revealed that co-doping TiO2 with chromium and iron metal ion demonstrated twice the photocatalytic activity for photodecomposition of gaseous-isopropyl alcohol when compared with single (Cr/Fe) doped TiO2 nanoparticles when exposed to visible light. The reviewed work estimated the optimal amount of Ce for Ce/N co-doped TiO2 at 0.05 grams. Different works of literature reviewed show that doping TiO2 with different transition metals reduces the band-gap for easy absorption of visible light and improvement in the photocatalytic activities of the nanoparticles.

The potentials of boron-doped (nitrogen deficient) and nitrogen-doped (boron deficient) BNNT photocatalysts for decontamination of pollutants from water bodies.

This work investigates the structural, elastic, electronic, and photoabsorption properties of boron- (N-deficient) and nitrogen- (B-deficient) doped single-walled boron nitride nanotube (SWBNNT) for photocatalytic applications for the first time. All calculations of the optimized systems were performed with DFT quantum simulation codes. The results of the structural analysis showed that SWBNNT is stable to both B and N dopants. It was also observed that the photodecomposition activity of the B-doped nanotube improved significantly under the condition of slight compressive stress, while it decreased for the N-doped nanotube. Therefore, N-doped SWBNNT showed poor performance under external pressure. Both B and N-doped systems could narrow the wide band gap of SWBNNT to the photocatalytic region below 3 eV, therefore this material can be used as photocatalysts in water splitting for hydrogen evolution, dye degradation, wastewater treatment, etc. Analysis of the optical properties revealed that B-doped SWBNNT absorbs more photons in the visible range than the N-doped SWBNNT and can therefore be considered as a more efficient photocatalyst. In addition, it was found that all doped nanotubes are anisotropic since the absorption in one direction of nanotube axes is worse than the other.

Facile construction of sandwich-like composited Sm2MoO6/ZnO/rGO and its activity in photodecomposition of ibuprofen

In this study, Sandwich-like Sm2MoO6/ZnO/rGO (SMZG) composite is produced by the simple hydrothermal method. Various techniques are used to investigate the physicochemical characteristics and morphologies of these heterostructured photocatalysts. The SMZG nanocomposite was successfully formed and the efficiency was tested with photodegradation of Ibuprofen (IBP). XRD analysis confirmed the formation of the body-centered monoclinic structure of Sm2MoO6 compound anchored on the surface of the hexagonal primitive structure of ZnO. According to the DRS UV–Visible spectrum, the nanocomposite photocatalyst has the lowest bandgap (3.12 eV) when compared to Sm2MoO6 (SM), ZnO, and Sm2MoO6/ZnO (SMZ). Under visible-light irradiation for 90 min, the prepared Sm2MoO6/ZnO/rGO (loaded with 20 wt% of Sm2MoO6 and 10 wt% of rGO) accomplish ca. 96.73% IBP photodegradation. The optimum catalyst photodegradation processes can be analytically defined as a function of different catalysts, catalyst dose, and reaction medium pH. As per the scavenging experiments, O2•- radicals are the active species in photodegradation. All these findings provide fresh insight into how to build photocatalysts with high in photodegradation efficiency, inexpensive in cost, rapid response time, and reusability.

Fabrication of novel heterostructured catalyst Ag@AgCl/Bi2Ti2O7and its excellent visible light photocatalytic performance

An excellent visible light responsive heterostructured photocatalyst Ag@AgCl/Bi2Ti2O7 was successfully fabricated through solvothermal method and subsequent deposition-precipitation/co-sintering process. The phase structure, morphology, specific surface area, surface chemical composition and state, and light absorption ability of the samples were characterized. The as-prepared Ag@AgCl/Bi2Ti2O7 heterostructured composites exhibit an obvious enhanced visible light photocatalytic activity in photodecomposition of rhodamine B (RhB) compared to Ag/AgCl and Bi2Ti2O7. A possible photocatalytic mechanism was proposed based on photoelectrochemical measurement and free radical trapping experiments, the synergistic effect of surface plasmonic resonance (SPR) of Ag0 photoreduced from AgCl can decrease the recombination rate of photogenerated carriers via transferring electrons from the surface of Ag0 to Bi2Ti2O7, which accelerates the excellent visible light photocatalytic activity of Ag@AgCl/Bi2Ti2O7. Moreover, four-cycle photodegradation reaction process of RhB on Ag@AgCl/Bi2Ti2O7 indicates an excellent stability.

Visible active reduced graphene oxide-BiVO4-ZnO ternary photocatalyst for efficient removal of ciprofloxacin

A highly effective rGO-BiVO4-ZnO photocatalyst was synthesized by hydrothermal method and characterized by XRD, FE-SEM, HR-TEM, XPS, Photoluminescence, FT-Raman, FT-IR and Diffuse reflectance spectroscopy. The narrow peaks of rGO-BiVO4-ZnO reveal good crystallinity and strong diffraction peaks of GO at 11.30° and 42.43° correspond to the layered structure of GO. Average crystalline size of the rGO-BiVO4-ZnO was 35 nm. TEM images reveal the presence of nanorods of ZnO and pristine structure of BiVO4 on the rGO sheet. The band gap energy for rGO-BiVO4-ZnO is 2.35 eV. The reduced PL emission at 524.6 nm by rGO-BiVO4-ZnO relative to the synthesized ZnO, reveal a decrease of recombination of the photon-induced electron-hole pair by loading of BiVO4 on ZnO. Ternary nanocomposite rGO-BiVO4-ZnO exhibits highest photodecomposition activity, achieving 98.4% decomposition efficiency for ciprofloxacin in 60 min under visible light irradiation. Photogenerated holes play a major role in the photocatalytic decomposition of ciprofloxacin (CIP), Low cost rGO-BiVO4-ZnO is stable and recyclable for effective decomposition of ciprofloxacin. Based on the GC-MS analysis, the CIP decomposition pathway as well as decomposition mechanism of piperazine ring oxidation are proposed. The photodecomposition efficiency is mainly due to charge transfer and excellent electron hole separation by doping of rGO.

Synthesis and characterization of Ag doped cadmium sulfide/multi walled carbon nanotubes: Structural, and photocatalysis studies

Silver doped cadmium sulfide as quantum dots/multi walled carbon nanotubes composites were prepared by chemical methods. The prepared nano-samples were characterized by photoluminescence (PL) and UV–Vis spectroscopy, field emission-SEM, Dynamic light scattering (DLS), Brunauer–Emmett–Teller (BET), and X-ray diffraction (XRD). The DLS result of as-prepared samples was indicated the average size of 5.0, 5.5, and 6.0 nm for CdS quantum dots, CdS/MWCNTs, and CdS/MWCNTs nanocomposites, respectively. The band gap values of CdS QDs, CdS/MWCNTs, Ag-CdS/MWCNTs (2:1), Ag-CdS/MWCNTs (1:1) and Ag-CdS/MWCNTs (2:1) were 2.80, 2.75, 2.70, 2.55, and 2.55 eV, respectively. The specific surface area values of CdS QDs, Ag-CdS/MWCNTs, and Ag-CdS/MWCNTs (1:1) were 47.245, 234.591, and 275.365 m2 g−1, respectively. The prepared samples were investigated towards photo-degradation of crystal violet as a dye compound under ultraviolet light illumination. The amount of photo-decomposition activity of the Ag doped CdS/MWCNTs nanocomposites could be substantially raised. The research work result provides an effective method to prepare several nano-photocatalysts with UV light sensitive progress for degradation of dye compounds.

RETRACTED ARTICLE: Synthesis and characterization of Cr2S3–Bi2O3 nanocomposites: photocatalytic, quenching, repeatability, and antibacterial performances

In this study, the bismuth (III) oxide (Bi2O3) nanoparticles and chromium (III) sulphide/bismuth (III) oxide (Cr2S3–Bi2O3) nanocomposites were prepared hydrothermally by sonochemical assisted methods. The different devices such as Scanning Electron Microscopy, UV–vis spectroscopy, dynamic light scattering and, X-ray analysis were used for evaluation of the morphology and structural data of the prepared catalyst. The photo-degra dation activity of Cr2S3–Bi2O3 was comparing with Bi2O3. It was revealed that the Cr2S3–Bi2O3 could raise their photo-degradation performance for the removal of Malathion as an organophosphate insecticide under visible and UV light irradiation. The result from XRD and UV–vis DRS studies were shown the values of crystallite size and band gap for Bi2O3, and Cr2S3–Bi2O3-1 have obtained from and found 50.12, 58.45 nm and 2.81, 2.54 eV, respectively. The optimal condition of Malathion photo-degradation was found at time: 50 min, and pH: 5 for the Cr2S3–Bi2O3-2 with 90.5, and 97.5% photo-decomposition activity after 50 min under visible and UV light elucidation, respectively. The bactericidal possible of the prepared catalyst was appraised by using the disk diffusion proceeding and determining the lowest inhibitory and bactericidal concentration versus the two various bacteria groups. The results demonstrated that Cr2S3–Bi2O3-2 nanocomposites had high antibacterial properties.

Photocatalytic degradation of 4-chlorophenol with the use of FTO/TiO2/SrTiO3 composite prepared by microwave-assisted hydrothermal method

Microwave-assisted hydrothermal method was applied to obtain SrTiO3 photocatalyst by transformation of a thin TiO2 layer deposited on the conducting solid substrate (FTO-glass) via dissolution-precipitation reaction in alkaline solution. The influence of Sr2+ ions concentration on crystallinity, composition as well as photoelectrochemical and photocatalytic properties of the resultant materials was investigated. The XRD studies indicated the presence of some amount of co-deposited SrSiO3 due to reaction of metasilicates released from the glass substrate (not covered with FTO film). However, the process of glass dissolution was substantially prevented by protection of the back side of the sample with a Teflon tape. The best activity in photodecomposition of 4-chlorophenol under irradiation with 365 nm diode was obtained for FTO/TiO2/SrTiO3 composite fabricated in 6 h synthesis in the solution containing 0.1 M Sr(NO3)2, at temperature of 180 °C. The photoelectrochemical properties of the composites and FTO/TiO2 electrode were studied in the solution of Na2SO4 under illumination with a xenon lamp. The increased photocurrent density and longer electron lifetime for the hybrid system in comparison to those of TiO2 was discussed in terms of suppressed recombination rate due to formation of TiO2/SrTiO3 interface. It was also found that the side product, SrSiO3, reveals an excellent adsorption properties with respect to methylene blue and therefore, the system SrTiO3/TiO2/FTO/glass/SrSiO3 may be used as bifunctional composite for adsorption and photocatalysis.

Effects of the conjugated structure of Fe–bipyridyl complexes on photoinduced electron transfer in TiO2 photocatalytic systems

Abstract [Fe II (dcbpy) 2 (H 2 O) 2 ] (dcbpy = 2,2′-bipyridine-4,4′-dicarboxylic acid) complex was synthesized through a simple method and used as a photosensitizer to improve the photocatalytic activity of TiO 2 in the photodegradation of phenol under visible light irradiation. X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectra, scanning electron microscopy, and transmission electron microscopy were used to characterize the structure and morphology of [Fe II (dcbpy) 2 (H 2 O) 2 ]/TiO 2 . It exhibited enhanced photocatalytic activity in photodecomposition of phenol in aqueous solution under visible light irradiation compared with that of pure TiO 2 . When one of ligand dcbpy was replaced by bpy (2,2′-bipyridine) or phen (1,10-phenanthroline), two novel composite catalysts, [Fe II (dcbpy)(bpy) 2 ]/TiO 2 and [Fe II (dcbpy)(phen) 2 ]/TiO 2 , were obtained and exhibited excellent photocatalytic activity like that of [Fe II (dcbpy) 2 (H 2 O) 2 ]/TiO 2 . Their different performance in the degradation of phenol, derived from their different interfacial interaction and electron transfer between complexes and TiO 2 surface, are discussed in detail. Based on research on the dynamical process of photocatalytic degradation of phenol, recycling stability, absorption spectra, photoelectrochemistry performance and cyclic voltammetry, trapping experiments, and density functional theory calculations of quantum chemistry, possible electron transfer mechanism are proposed, which can reasonably explain the different photocatalytic activities of these three novel catalysts.

Preparation and characterization of SrTiO3-Ag/AgCl hybrid composite with promoted plasmonic visible light excited photocatalysis

An efficient visible light responsive photocatalyst hybrid composite SrTiO3-Ag/AgCl was prepared via hydrothermal method and subsequent chemical precipitation/in-situ photoreduction at room temperature. The phase structure, morphology, element mapping distribution, surface chemical composition, specific surface area, and light absorption ability of the samples were characterized. The transient photocurrent response and electrochemical impedance under visible light illumination indicate that SrTiO3-Ag/AgCl composite possesses a more intense photocurrent response and a smaller surface resistance than SrTiO3 and Ag/AgCl due to the lower electrons-holes recombination. SrTiO3-Ag/AgCl composite exhibits an obvious promoted visible light excited photovcatalytic activity in photodecomposition of methyl orange, rhodamine B and phenol, compared to SrTiO3 and Ag/AgCl. A possible photocatalytic mechanism was proposed, indicating that the synergistic effect of surface plasmonic resonance of Ag0 photoreduced from AgCl and decreased the recombination rate of photogenerated carriers through transferring electrons from the surface of Ag0 to SrTiO3 promote the excellent photocatalytic activity of SrTiO3-Ag/AgCl. Moreover, the photodegradation reaction process of methyl orange, rhodamine B and phenol on SrTiO3-Ag/AgCl follows the pseudo-first-order kinetic model, and the reaction rate constants are approximately 10 times greater than those on Ag/AgCl. Four-recycling photocatalytic process of methyl orange on SrTiO3-Ag/AgCl also indicates a superior stability and durability.

One-Pot Fast Synthesis of Leaf-Like CuO Nanostructures and CuO/Ag Microspheres with Photocatalytic Application

A time- and energy- saving solution-based chemical precipitation method was developed to synthesize leaf-like CuO nanostructures. The morphology and size of the leaf-like CuO nanostructures could be simply manipulated by controlling the type and concentration of precursors, and the oriented attachment mechanism is responsible for the formation of leaf-like shape. With the concurrent reduction reaction and at appropriate concentration, CuO/Ag microspheres could be prepared and the growth mechanism is proposed. These two structures could serve as effective photocatalyst for the degradation of rhodamine B under visible light irradiation in the presence of hydrogen peroxide. Moreover, compared to pure CuO nanostructures, the photodecomposition activity of CuO/Ag microspheres increases by 42.9% due to plasmon-enhanced light absorption.

Siloxane-based metal–organic frameworks with remarkable catalytic activity in mild environmental photodegradation of azo dyes

Three new metal–organic frameworks (MOFs) were obtained from a siloxane dicarboxylic acid (CX), 4,4′-bipyridyne (BPy) or 1,2-bis(4-pyridyl)ethylene (EBPy) and copper or cobalt acetates. The compounds were characterized by IR spectroscopy, powder X-ray diffraction, energy-dispersive X-ray fluorescence (XRF), thermogravimetric analysis (TGA), dynamic water vapor sorption (DVS), electron microscopy (TEM, SEM), UV–vis diffuse reflectance and fluorescence measurements. These hydrophobic MOFs acted as efficient catalysts in two processes occurring in aqueous media. The best result in alkaline decomposition of hydrogen peroxide was 90% conversion after 30min. The catalytic activity in photodecomposition of Congo Red (CR) was followed in mild environmental conditions, i.e. under natural sunlight, without additional oxidation agents or pH adjustments. Unprecedented catalytic activity was found, especially for the Co complex with CX and EBPy, with discoloration efficiency of ca. 82% after 80min of exposure to sunlight. The obtained results, in terms of rate constants and efficiency are comparable with those reported for other catalytic systems in photoreactors or in the presence of H2O2. The best catalyst was also tested in a Fenton-like process and it was found that the addition of H2O2 doubles the rate constant and increases the efficiency to 97%. On the other hand, the remaining waters after CR photodecomposition were analyzed by mass spectrometry (ESI–MS) and it was concluded that “cleaner” water is obtained when the MOFs are used without addition of H2O2.

Polystyrene photodegradation with a styrene block copolymer containing TiO2 nanoparticle

Polystyrene (PS) photodegradation with a novel poly(styrene-block-acrylic acid) (PS-b-PAA) containing TiO2 nanoparticle photocatalyst was studied. The TiO2 nanoparticle contained anatase phase and showed methylene blue photodecomposition activity. In particular, the higher molecular weight PS736-b-PAA129 photocatalyst had a high ability in the photodegradation and showed good dispersity in PS matrix. The PS composite film transparency was nearly equal to that of PS. The composite showed good PS photodegradation behavior under the UV irradiation. The chain scission preferentially occurred, leading to the decrease of PS molecular weight. In addition, an additional methyl linoleate (ML) component caused an improvement of the chain scission activity to the composite.

Visible-light photodecomposition of acetaldehyde by TiO2-coated gold nanocages: plasmon-mediated hot electron transport via defect states

Skeletal gold nanocages (Au NCs) are synthesized and coated with TiO2 layers (TiO2-Au NCs). The TiO2-Au NCs exhibit enhanced photodecomposition activity toward acetaldehyde under visible light (>400 nm) illumination because hot electrons are generated over the Au NCs by local surface plasmon resonance (LSPR) and efficiently transported across the metal/semiconductor interface via the defect states of TiO2.

Annealing-free synthesis of C[sbnd]N co-doped TiO2 hierarchical spheres by using amine agents via microwave-assisted solvothermal method and their photocatalytic activities

The annealing-free synthesis of CN co-doped TiO2 hierarchical spheres is proposed in this study. C and N were doped into the TiO2 structure via a direct chelating process to the Ti-precursor by using different amine agents, including hexadecylamine (HDA), diethylamine (DEA), trimethylamine (TMA), and diethylenetriamine (DETA). CN co-doped TiO2 spheres (300nm to 500nm) composed of nanoparticles approximately 11nm to 13nm in size were obtained via an efficient microwave-assisted solvothermal reaction at 190°C for 60min. The effects of C and N doping by using different amine compounds on the bandgap energy and photocatalytic performance of TiO2 were investigated. Among the amine compounds, DETA provided the highest chelating efficiency because it provides two primary amine groups, which resulted in the highest C and N doping concentrations and the largest degree of bandgap narrowing (2.77eV); nevertheless, the high chelating ratio of C and N restrained the crystallization of TiO2 and considerably decreased its photocatalytic activity. The use of TMA produced optimal C and N doping concentrations, which effectively reduced the bandgap of TiO2 to 2.85eV without affecting its crystallization. Its photodecomposition activity to rhodamine B was eightfold of that of commercial Degussa P25 powders under visible light irradiation.

Influence of Al doping on microstructural, optical and photocatalytic properties of sol–gel based nanostructured zinc oxide films on glass

Al content dependent defect concentration (oxygen vacancies) and Rhodamine 6G dye photodecomposition activity of sol–gel nanostructured ZnO thin films.

Does noble metal modification improve the photocatalytic activity of BiOCl?

Noble metal-surface-deposited BiOCl photocatalysts were prepared through photo-deposition and used for photodecomposition of Rhodamine B (RhB). The received materials were characterised using X-ray photoemission spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), and X-ray diffraction (XRD) to understand the influence of surface deposited noble metals. The results showed that the noble metal species on the surface of BiOCl are in metallic state, which also brought about enhanced light absorption in broad UV–vis region due to plasmonic effects induced by the surface-deposited noble metal species. All the samples showed good activity in photodecomposition of RhB under UV-light irradiation, but only Ag/BiOCl was more active than bulk BiOCl. The mechanism of the different reactivity of these noble-metal modified BiOCl was tentatively proposed based on the band structure and the interactions between noble metals and the BiOCl.

Nanoparticles: Well Shaped Mn3O4 Nano‐octahedra with Anomalous Magnetic Behavior and Enhanced Photodecomposition Properties (Small 4/2011)

AbstractVery uniform and well shaped Mn3O4 nano‐octahedra are synthesized using a simple hydrothermal method under the help of polyethylene glycol (PEG200) as a reductant and shape‐directing agent. The nano‐octahedra formation mechanism is monitored. The shape and crystal orientation of the nanoparticles is reconstructed by scanning electron microscopy and electron tomography, which reveals that the nano‐octahedra only selectively expose {101} facets at the external surfaces. The magnetic testing demonstrates that the Mn3O4 nano‐octahedra exhibit anomalous magnetic properties: the Mn3O4 nano‐octahedra around 150 nm show a similar Curie temperature and blocking temperature to Mn3O4 nanoparticles with 10 nm size because of the vertical axis of [001] plane and the exposed {101} facets. With these Mn3O4 nano‐octahedra as a catalyst, the photodecomposition of rhodamine B is evaluated and it is found that the photodecomposition activity of Mn3O4 nano‐octahedra is much superior to that of commercial Mn3O4 powders. The anomalous magnetic properties and high superior photodecomposition activity of well shaped Mn3O4 nano‐octahedra should be related to the special shape of the nanoparticles and the abundantly exposed {101} facets at the external surfaces. Therefore, the shape preference can largely broaden the application of the Mn3O4 nano‐octahedra.