Effective Photocatalytic Properties Research Articles

A Calcination-Free Sol-Gel Method to Prepare TiO2 -Based Hybrid Semiconductors for Enhanced Visible Light-Driven Hydrogen Production.

In recent years, the sol-gel method has been extensively utilized to develop efficient and stable organic semiconductor composite titanium dioxide (TiO2 ) photocatalysts. However, the high-temperature calcination requirements of this method consume energy during preparation and degrade encapsulated organic semiconductor molecules, resulting in decreased photocatalytic hydrogen production efficiency. In this study, we found that by selecting an appropriate organic semiconductor molecule, 1,4-naphthalene dicarboxylic acid (NA), high-temperature calcination can be avoided in the sol-gel process, yielding an organic-inorganic hybrid material with stable and effective photocatalytic properties. The uncalcined material displayed a hydrogen production rate of 2920±15 μmol g-1 h-1 , which was approximately twice the maximum production rate observed in the calcined material. Likewise, the specific surface area of the uncalcined material, at 252.84 m2 g-1 , was significantly larger compared to the calcined material. Comprehensive analyses confirmed successful NA and TiO2 doping, while UV-vis and Mott-Schottky tests revealed a reduced energy bandgap (2.1 eV) and expanded light absorption range. Furthermore, the material maintained robust photocatalytic activity after a 40-hour cycle test. Our findings demonstrate that by using NA doping without calcination, excellent hydrogen production performance can be achieved, offering a novel approach for environmentally friendly and energy-saving production of organic semiconductor composite TiO2 materials.

Nano‐SH‐MOF@Self‐Assembling Hollow Spherical g‐C3N4 Heterojunction for Visible‐Light Photocatalytic Nitrogen Fixation

AbstractMetal‐organic frameworks (MOFs)@g‐C3N4 heterojunctions are widely investigated as one of the most potential photocatalysts for N2 fixation owing to the visible absorption and effective photocatalytic properties. It is still a huge challenge to synthesize hollow spherical C3N4 coated with Nano‐MOF layers towards efficient visible photocatalytic activity on N2 fixation. In this work, the paramagnetic hollow spherical C3N4 (H‐C3N4) are coated with free radical MOF with sulfhydryl ligand (Nano‐SH‐MOF)[Zn2(DSBDC)] by self‐assemble method. The C8 M2 samples (the mass ratio of H‐C3N4 to Nano‐SH‐MOF is 8 : 2) exhibited an improved photocatalytic activity, which is almost 5.4 times higher than the pure H‐C3N4. The improved photocatalytic activity is also discussed in this work. It can be imagined that this work may be helpful for the hollow spherical C3N4 based heterojunction and MOF‐based heterojunction photocatalysts with effective photocatalytic nitrogen fixation.

Multipurpose Solar Photoelectrochemical Hybrid Multilayer Films Based on Porphyrin and Preyssler Type Polyoxometalates for Solar Cell and Ag Nanomaterial Synthesis

Multilayer films with electrostatic interaction between Preyssler,s Polyanions (NH4)14[NaP5W30O110]14- .31H2O and tetracationic free base porphyrin [H2TN+(Me)3PyP]4+ have been alternately deposited on quartz and ITO substrates. and characterized by UV-visible absorption spectroscopy to follow the successive deposition of multilayer film. Solution phase interaction of both components revealed the stiochiometric ratio of the electrostatic complex formed . The morphology and composition of films were studied by atomic force microscopy and X-ray photoelectron spectroscopy (XPS ) .While permeability to cations in aqueous media and redox behavior were studied by cyclic voltametry . The solar photoctalytic activity of hybrid films is identified by TEM images obtained after heterogeneous aqueous photoreduction of Ag2SO4(aq) and KAuCl4 (aq) to yield diversified nanostructures . The study is first and initial report on preyssler type polyanions and porphyrin based heterogenous photocatalysis that provide a green, solar and multiple applications for precious metal recovery as nanoparticle ,sustainable wastewater purification and solar photocurrent generation.Polyoxometalates (POMs) are metal−oxygen framework of early metal elements in their highest oxidation state , able to undergo reversible, stepwise, multielectron-transfer reactions, which are the basis for many catalytic processes[1].These polyanions clusters exhibit applications in catalysis, medicine, materials science [2]. They offer effective photocatalytic properties in oxidation and reduction processes. On photolysis, the high oxidizing ability of excited POMs can lead to the degradation of a variety of organic compounds such as pollutants, leading to a process for water purification [3]. In the presence of a sacrificial electron donor , their photolysis lead to the formation of reduced POMs which can in turn reduce metallic ions. It could be a good alternative for precious metals recovery or synthesis of metal nanoparticles. [4,5]. However, polyoxometalates absorb in the uv part of spectrum, thus they require UV excitation, which cease its large-scale environmental application. One of obvious strategy is to couple it with some chromophore group which can be sensitized by visible light. Metal porphyrins are attractive components in materials because of their appealing chemical and photochemical properties: high stability, intense visible absorption bands, long-lived excited states, and tunability by chemical derivatization [2]. Figure 1.1 R.H.S. Representation of the porphyrin used 5, 10, 15, 20-Tetrakis (4-trimethylammoniophenyl) porphyrin tetra(p-toluenesulfonate), namely [H2TN+(Me)3PyP]4+) used with the Preyssler type (NH4)14[NaP5W30O110]14- .31H2O . L.H.S. UV-visible record on quartz and ITO shows layer by layer absorbance. Formation of Multilayer Films :H2TN+(Me)3PyP4+] / [(NH4)14[NaP5W30O110]14- .31H2O ] The alternate deposition of positively charged porphyrin, H2TN+(Me)3PyP4+, and negatively charged [NaP5W30O110]14-on slides of quartz and Indium tin Oxide (ITO) lectrodes by layer-by-layer were performed.

Synthesis of titanium dioxide nanoparticles with renewable resources and their applications: review.

Metal-oxide nanoparticles have reached a wide range of applications in the last ten years. Titanium dioxide nanoparticles stand out with their unique crystal structure and near-perfect physical and chemical properties at nanoscales (crystal size between 10-100 nm). It has created many applications with its white pigment, semiconductor state, and effective photocatalytic properties, but the synthesis of these nanoparticles is very damaging to nature. Titanium dioxide nanoparticles, which can be synthesized with toxic solvents or high-energy machines, have started to be synthesized by the green synthesis method, which has been a cheap and easy method in recent years. The application areas of these nanoparticles synthesized with renewable resources (leaves, roots, seeds, etc.) are increasing day by day. This article gives information about the synthesis of titanium dioxide nanoparticles with renewable resources and the application of these nanoparticles synthesized by means of chemical and green synthesis methods.

Liquid-Phase Deposition Synthesis of ZIF-67-Derived Synthesis of Co3O4@TiO2 Composite for Efficient Electrochemical Water Splitting

In this article, a novel Co3O4@TiO2 composite is synthesized by applying two-step methods. ZIF-67 is synthesized and used as a template for the synthesis of the composite. The composite is designed by using the effective photocatalytic properties of Co3O4 and TiO2. The resulting synthesized composite is supposed to offer superior properties compared to their counterparts. The synthesized Co3O4@TiO2 composite is characterized by powder X-ray diffraction (PXRD), Brunauer–Emmet–Teller (BET), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Electrochemical water splitting, including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) studies on the Co3O4@TiO2 composite, is evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) analysis in a 2M aqueous KOH electrolyte. The current generation stability of these samples is deliberated by chronoamperometric measurements. It is observed, from LSV results at a 1 mV/s scan rate, that metal oxides incorporated on other metal oxides have a higher current density and lower onset potential as compared to pure metal oxides. From the obtained results, it has become evident that synthesized studies on the Co3O4@TiO2 composite possess significant potential for electrochemical water splitting with the lowest onset potential, highest current density, better OER, and HER activity.

Simple preparation of magnetic, antibacterial and photo-catalyst NiFe2O4@TiO2/Pt nanocomposites

Firstly nickel ferrite nanoparticles were synthesized via a simple precipitation method. Then mono-disperse platinum nanoparticles and NiFe2O4@TiO2/Pt nanocomposites were synthesized by a facile sol-gel procedure. The structure, phase and crystallite size of the magnetic and photo-catalyst products were characterized by X-ray diffraction pattern (XRD). The morphology and size of the nanostructures were surveyed by scanning electron microscopy (SEM). The purity of the samples was confirmed by Fourier transform infrared (FT-IR) spectroscopy. Vibrating sample magnetometer (VSM) illustrated that nickel ferrite nanoparticles have super paramagnetic behaviour. The photo catalytic behaviour of NiFe2O4@TiO2/Pt nanocomposites was approved using the fast degradation of two various azo dyes under visible and ultra violet light irradiation. The results show that nanocomposites have feasible magnetic feature for easy separation and effective photo catalytic properties for purification of organic dye contaminants. The antibacterial behaviour of NiFe2O4@TiO2/Pt nanocomposites was evaluated using degradation of E coli bacteria. Keywords: Photo-catalyst; Nanostructures; Nanocomposite; Magnetic

Photo-catalyst Fe–Pt nanocomposite: mechanical preparation of iron nanoparticles and simple synthesis of platinum nanoparticles

Firstly iron nanoparticles were synthesized via a simple mechanical ball-milling method from bulk iron micro powders. Then mono-disperse platinum nanoparticles and Fe–Pt nanocomposites were synthesized by a facile hydrothermal procedure. The structure, phase and crystallite size of the magnetic and photo-catalyst products were characterized by X-ray diffraction pattern. The morphology and size of the nanostructures were surveyed by scanning electron microscopy. The purity of the samples was confirmed by Fourier transform infrared spectroscopy. Vibrating sample magnetometer illustrated that Fe nanoparticles have super paramagnetic behaviour. The photo catalytic behaviour of Fe–Pt nanocomposites was approved using the fast degradation of three various azo dyes under visible and ultra violet light irradiation. The results show that nanocomposites have feasible magnetic feature for easy separation and effective photo catalytic properties for purification of organic dye contaminants.

Fabrication of a Cu2O/Au/TiO2 composite film for efficient photocatalytic hydrogen production from aqueous solution of methanol and glucose

A novel Cu2O/Au/TiO2 photocatalyst composite film was fabricated on a copper substrate for photocatalytic hydrogen production. The composite films, Cu2O/Au/TiO2, were stepwise synthesized by using electrochemical deposition, photodeposition, and coating methods. First, a Cu2O film was synthesized using the electrochemical deposition method, after which Au was deposited onto the Cu2O film through in-site photodeposition. Finally, TiO2 was coated on the surface of the Cu2O/Au film. Its morphology and surface chemical composition was characterized by SEM, TEM, XRD and XPS. The optical characteristics (UV–Vis DRS, PL spectrum) of the films were also examined. The photocatalytic hydrogen production rate of the Cu2O/Au/TiO2 composite film from a 20% vol. methanol solution increased to125.3mmol/h/m2 under 300W xenon lamp light irradiation. Compared to the TiO2 (13.5mmol/h/m2) film and Cu2O/TiO2 film (83.2mmol/h/m2), the Cu2O/Au/TiO2 film showed excellent photocatalytic performance for hydrogen generation. The Cu2O/Au/TiO2 film has highly effective photocatalytic properties, which are attributed to the Z-scheme system and can not only enhance the absorption of solar light but also suppress the recombination of photogenerated electron-hole pairs. It is worth noting that by introducing Au into the interface of Cu2O/TiO2, the surface plasmon resonance (SPR)-induced local electric field formed at the Au site induces a Z-scheme charge transfer pathway inside the composite film (Cu2O/Au/TiO2), which promotes both the charge of the separation efficiency and redox ability of the photogenerated electron-hole pairs.

Theoretical investigation of electron structure and surface morphology of titanium dioxide anatase nano-particles

Titanium dioxide is a widely used material. It is white pigment and a very effective UV filter, nano-particles of titanium dioxide show effective photocatalytic properties. Also, it is used in the manufacturing of dye-sensitized solar cells. Recent experimental studies show that the properties (e.g. photocatalytic performance, adsorption, reflectance, adhesion, carrier transportation properties, nano-toxicity, etc.) of the titanium dioxide nano-particles are dependent on their shape, sizes and surface morphology. Therefore, both experimental and computational study of TiO2 nano-clusters and the development of both experimental and computational techniques for the study are the actual goals. Thus, in the current work, a theoretical study of anatase nano-particles, their shape, electron characteristics, surface morphology, the influence on adsorption has been performed. A new methodology based on AlteQ approach for the accurate estimation of the electron density, surface, volume characteristics in a reasonable time for theoretical study of nineteen anatase nano-clusters of different forms (cub, ellipsoid, sphere, cuboid) and sizes from Ti25O50 to Ti650O1300 has been applied. The comparison of the AlteQ and the first principles methods has been performed and the applicability of the AlteQ approach has been confirmed. The computations have been performed at http://www.chemosophia.com/ using “Electron properties calculation: Integration over atomic basins” software. The study showed that the ratio of the summary atomic external surface area of oxygens varies in the wide range 0.42–0.65 dependently on the shape and the surface morphology of a nano-cluster. The maximal values (0.52–0.65) are typical of elongated nano-clusters with deep and long furrows observed on the faces parallel to c axis while the least values (0.42–0.43) are observed in the cases of spherical nano-clusters with smoother surface. Thus, elongated TiO2 nano-clusters with deep and long furrows can adsorb preferably positively charged and acidic centers of compounds which are mostly complementary to the oxygens of TiO2 nano-particles, while spherical nano-clusters with smoother surface are mostly effective in the interactions with the negatively charged and basic adsorptive centers of compounds. Linear relations of the number of electrons observed in the atomic overlaps to the number of electrons belonging to separatrices and to the atomic volume have been obtained.

Single cyanide-bridged Mo(W)/S/Cu cluster-based coordination polymers: Reactant- and stoichiometry-dependent syntheses, effective photocatalytic properties

The systematic study on the reaction variables affecting single cyanide-bridged Mo(W)/S/Cu cluster-based coordination polymers (CPs) is firstly demonstrated. Five anionic single cyanide-bridged Mo(W)/S/Cu cluster-based CPs {[Pr4N][WS4Cu3(CN)2]}n (1), {[Pr4N][WS4Cu4(CN)3]}n (2), {[Pr4N][WOS3Cu3(CN)2]}n (3), {[Bu4N][WOS3Cu3(CN)2]}n (4) and {[Bu4N][MoOS3Cu3(CN)2]}n (5) were prepared by varying the molar ratios of the starting materials, and the specific cations, cluster building blocks and central metal atoms in the cluster building blocks. 1 possesses an anionic 3D diamondoid framework constructed from 4-connected T-shaped clusters [WS4Cu3]+ and single CN− bridges. 2 is fabricated from 6-connected planar ‘open’ clusters [WS4Cu4]2+ and single CN− bridges, forming an anionic 3D architecture with an “ACS” topology. 3 and 4 exhibit novel anionic 2-D double-layer networks, both constructed from nest-shaped clusters [WOS3Cu3]+ linked by single CN− bridges, but containing the different cations [Pr4N]+ and [Bu4N]+, respectively. 5 is constructed from nest-shaped clusters [MoOS3Cu3]+ and single CN− bridges, with an anionic 3D diamondoid framework. The anionic frameworks of 1-5, all sustained by single CN− bridges, are non-interpenetrating and exhibit huge potential void volumes. Employing differing molar ratios of the reactants and varying the cluster building blocks resulted in differing single cyanide-bridged Mo(W)/S/Cu cluster-based CPs, while replacing the cation ([Pr4N]+ vs. [Bu4N]+) was found to have negligible impact on the nature of the architecture. Unexpectedly, replacement of the central metal atom (W vs. Mo) in the cluster building blocks had a pronounced effect on the framework. Furthermore, the photocatalytic activities of heterothiometallic cluster-based CPs were firstly explored by monitoring the photodegradation of methylene blue (MB) under visible light irradiation, which reveals that 2 exhibits effective photocatalytic properties.

Two Distinct Dimeric Heterothiometallic W/S/Cu Clusters with Effective Photocatalystic Property

Two heterothiometallic W/S/Cu dimeric clusters, {[WS4Cu4Cl2(phen)2]2·MeCN} (1) and {[CuCl(phen)2]2[WOS3Cu3Cl2(phen)]2} (2), were synthesized by the reactions of 1,10-phenanthroline (phen), CuCl and (NH4)2WS4 or (NH4)2WOS3, in DMF. 1 and 2 were characterized by elemental analyses, IR, UV–Vis, X-ray powder and single crystal diffractions. 1 exhibits a rare dimeric architecture, constructed by two parallel pentanuclear planar ‘open’ [WS4Cu4Cl2(phen)2] clusters linked together via a pair of μ 2-Cl bridges. While 2 consists of the five-coordinated cation [CuCl(phen)2]+ and the dimeric anionic cluster {[WOS3Cu3Cl2(phen)]2}2−, which is fabricated by a pair of tetranuclear nest-shaped clusters, connected by two μ 2-Cl bridges. Moreover, the photocatalytic activities of heterothiometallic clusters were firstly explored by monitoring the photodegradation of methylene blue (MB), which reveals that 1 and 2 both exhibit effective photocatalytic properties under Xe-illuminator irradiation.

Solvent-induced syntheses of three heterothiometallic W/S/Cu cluster-based coordination polymers with isomeric architectures and effective photocatalytic properties

Reactions of (NH4)WS4, CuCN and pyridine (Py) in different reaction solvents, namely DMF, DMSO and aniline, generated three isomeric heterothiometallic W/S/Cu cluster-based coordination polymers [WS4Cu4(CN)2(Py)4]n (1 and 2) and {[WS4Cu4(CN)2(Py)4]2·4CH3CN}n 3. All three complexes are constructed from planar ‘open’ [W(µ3-S)4Cu4]2+ clusters, CN− bridges and terminal Py ligands, but exhibit distinct architectures, consisting of a unique 1-D serrated chain for 1, a 2-D (4,4) network for 2 and a 1-D linear chain for 3. The photocatalytic activities of complex 1 were explored by monitoring the photodegradation of methylene blue, revealing that this complex exhibits effective photocatalytic properties under visible light irradiation.

Effective photocatalytic properties of N doped Titanium dioxide nanotube arrays prepared by anodization

Abstract Nitrogen-doped titanium dioxide (TiO2) nanotube arrays were synthesized by anodization in ethylene glycol electrolyte and annealing in ammonia at 500 °C. Detailed analysis showed that the nitrogen-doped titania nanotubes were pure anatase of ordered structure, with a crystallite size of 8.5 nm. The doping nitrogen atoms were induced on the interstitial sites and substitutional sites and the ratio of oxygen vacancies increased to 27.15 %, resulting in an add-on peak in the absorption spectrum and extended the absorption from 387 to 618 nm. The photocatalytic activity of the nitrogen-doped TiO2 nanotubes was evaluated by photocatalytic degradation of methyl blue under visible light irradiation. Significant improvement of photocatalytic activity under visible light irradiation was observed. We assumed the nitrogen doping induced the effect produced by nitrogen atoms, Ti3+ cations and oxygen vacancies and the size effect of the TiO2 crystallite should be responsible for the effective photocatalytic a...