Facile Preparation of PVA-AA/TiO2 Composite Gel Particles and Their Tunable Photo-catalytic Property for the Degradation of Methyl Orange

In the presence of titanium dioxide powder, cross-linking reaction between commercial polyvinyl alcohol(PVA)-based macromonomer and acrylic acid(AA) was initiated with potassium persulfate in an emulsifying system. As a result, PVA-AA/TiO2 composite gel particles were obtained. The morphology and composition of the particles were analyzed with scanning electron microscopy(SEM), energy scattering x-ray spectroscopy(EDS), Fourier infrared spectroscopy(FTIR), and thermogravimetric analysis(TGA). The analysis results confirmed that the particles were the expected ones. TiO2 was dispersed homogeneously within the spheroidal particles. Compared to the control gel, the composite gel particles not only contained Ti element but also showed higher thermal stability. In addition, the photo-catalytic behavior of the particles for the degradation of methyl orange contained in aqueous solution was examined. The particles exhibited photocatalytic characteristic for the degradation of the model dye, which could be modulated by simply varying the amount of cross-linking agent or TiO2. The photo-catalytic degradation percentage of methyl orange maintained at 91%-96% after using the particles three times, which indicated that TiO2 could played its role repeatedly via being fixated within polyvinyl alcohol-based gel.

Photo-Catalytic Activity of Ca_1-xNi_xS Nanocrystals

Ca1-xNixS (0 ≤ x ≤ 0.05) nanocrystals have been synthesized by facile solid state reaction method. Synthesized nanocrystals are further etched with mild acid solutions to reduce the particle size, which augments the surface to volume ratio and confinement of carriers. Crystallographic and morphological characterizations of synthesized nanomaterials have been done by X-ray diffraction and electron microscopy, respectively. Comparison of the diffraction and electron microscopy studies reveal the formation of single crystalline nanostructures. Optical characterization of synthesized nanomaterials has been done by UV-vis. absorption spectroscopic studies. The photo-catalytic activity of synthesized nanomaterials under UV irradiation has been tested using methylene blue (MB) dye as a test contaminant in aqueous media. Photo-catalytic behaviour dependence on dopant concentration and etching has been thoroughly studied to explore the potential of synthesized nanomaterials for next era optoelectronic industrial applications as well as polluted water purification.

Ru/Pt@BSA nanoparticles for efficient photo-catalytic oxidation of NAD(P)H and targeted cancer treatment under hypoxic conditions

Photo-catalytic oxidation of intracellular nicotinamide adenine dinucleotide(2'-phosphate)(NAD(P)H)has attracted much attention for cancer therapy.However,the general oxygen-dependent mechanism heavily depresses the efficacy in hypoxic tumors.To solve this problem,herein platinum nanoparticles(Pt NPs)with catalase-like(CAT-like)and catalytic H_(2)evolution activities were introduced as a powerful assistant to enhance the photo-catalytic NAD(P)H oxidation of Ru1([Ru(phen)2(PIP-OCH_(3))]^(2+),phen=1,10-phenanthroline,PIP-OCH_(3)=2-(4-methoxy phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline)under hypoxic and even oxygen-free conditions.Firstly,Pt NPs can transform the original and in situ formed H_(2)O_(2)once again into O_(2)by the CAT-like activity,thus relieving tumor hypoxia and realizing cyclic utilization(at least in part)of the precious oxygen in hypoxia.Secondly,Pt NPs can also be served as H_(2)evolution catalysts while using Ru1 as the photosensitizer and NAD(P)H as the electron and proton donor.In this process,NAD(P)H is oxidized without the participation of oxygen,which can provide an effective way even under oxygen-free conditions.Via co-encapsulation of Rul and Pt NPs in bovine serum albumin(BSA)with tumor targeting ability,the resultant Ru/Pt@BSA could photo-catalyze intracellular NAD(P)H oxidation under hypoxic conditions(3%O_(2)),and exhibited an efficient and selective anticancer activity both in vitro and in vivo.Our results may provide new sights for efficient and targeted cancer treatment underhypoxic conditions.

Achieving simultaneous Cu particles anchoring in meso-porous TiO_(2) nanofabrication for enhancing photo-catalytic CO_(2) reduction through rapid charge separation

A facile solvo-thermal approach was successfully employed to prepare titanium oxide (TiO_(2)) nano-aggregates with simultaneous copper particles anchoring. The as-synthesized composite could convert CO_(2) into CH_(4) and CO products under simulated solar irradiation. The impact of copper loading amounts on the photo-reduction capability was evaluated. It was found proper amount of Cu loading could enhance the activity of CO_(2) photo-reduction. As a result, the optimal composite (TiO_(2)^(-)Cu-5%) consisting of TiO_(2) supported with 5% (mole ratio) Cu exhibits 2.2 times higher CH_(4) yield and 3 times higher CO yield compared with pure TiO_(2). Conduction band calculated from the band gap and valence X-ray photoelectron spectroscopy (XPS) indicated TiO_(2) nano-aggregates have suitable band edge alignment with respect to the CO_(2)/CH_(4) and CO_(2)/CO redox potential. Furthermore, with involving of Cu particles, an efficient separation of photo-generated charges was achieved on the basis of photocurrent response and photoluminescence spectra results, which contributed to the improved photo-catalytic performance. The present work suggested that the Cu-decorated TiO_(2) could serve as an efficient photo-catalyst for solar-driven CO_(2) photo-reduction.

Pd-MnO_2 nanoparticles/TiO_2 nanotube arrays(NTAs) photo-electrodes photo-catalytic properties and their ability of degrading Rhodamine B under visible light

Pd-MnO2/TiO2 nanotube arrays（NTAs） photo-electrodes were successfully fabricated via anodization and electro deposition subsequently; the obtained Pd-MnO2/TiO2 NTAs photo electrodes were analyzed by scanning electron microscopy（SEM）, X-ray diffraction（XRD） and characterized accordingly. Moreover, the light harvesting and absorption properties were investigated via ultraviolet–visible diffuse reflectance spectrum（DRS）; photo degradation efficiency was investigated via analyzing the photo catalytic degradation of Rhodamine B under visible illumination（xenon light）. The performed analyses illustrated that Pd-MnO2 codoped particles were successfully deposited onto the surface of the TiO2 nanotube arrays;DRS results showed significant improvement in visible light absorption which was between400 and 700 nm. Finally, the photo catalytic degradation efficiency results of the designated organic pollutant（Rhodamine B） illustrated a superior photocatalytic（PC） efficiency of approximately 95% compared to the bare TiO2 NTAs, which only exhibited a photo catalytic degradation efficiency of approximately 61%, thus it indicated the significant enhancement of the light absorption properties of fabricated photo electrodes and their yield of UOH radicals.

A photo-catalytic reactor for degrading volatile organic compounds(VOCs)in paper mill environment

Volatile organic pollutants such as benzene and formaldehyde are commonly detected in the ambient air of paper mills.To remove these pollutants from the air,a photo-catalytic reactor was developed in this study.The reactor had a series of honeycomb aluminum meshes coated with nanosized titanium dioxide as the catalyst for the degradation reactions of gaseous pollutants.Both formaldehyde and benzene could be completely degraded in the reactor.However,the degrading time for benzene was much longer than that for formaldehyde,and the degradation rate of benzene decreased with increasing initial benzene concentration.It was found that the reaction pathway for formaldehyde in the mixture was different from that in its single component form,and it took about two times longer time to be degraded than that for its single component form.The reaction pathway of benzene was similar in either case although the degradation time for benzene was about 50%shorter in the mixture form.

Fabrication of self-organized TiO_2 nanotubes by anodic oxidation and their photocatalysis

Self-organized TiO2 nanotubes were prepared on titanium foils at anodizing voltage of 20V in 0.5% HF solution for 2030min in order to provide a novel high-efficiency photocatalyst. And the resulting TiO2 nanotubes, in periodic ring structures around their exteriors, are open on the top, while closed on the bottom. After annealing for 3h in ambient atmosphere, the anatase phase was found, with the increasing content, in the originally amorphous TiO2 nanotubes treated at 350, 400 and 450℃; whereas the rutile phase emerged at 500℃, and the nanotube architecture could be preserved till 550℃. Furthermore, TiO2 nanotubes, fabricated at anodizing voltage of 20V for 20min and then annealed at 400℃, possesses the best photo-catalytic activity, i.e. the decolourisation of methyl orange irradiated for 40min is 99.6%.

Preparation of Ce^(4+),Sb^(3+)-Codoped TiO_2 Films in Electric Field Heating-Treatment

Titania is an important catalytic material for photo-catalytic applications, and the sol-gel process is one of the most appropriate technologies to prepare TiO2 thin films. In the present paper, the Ce4+, Sb3+-codoped TiO2 films were prepared by sol-gel method, which were heat-treated with an applied electric filed. The phase transformation behavior of Ce4+, Sb3+-codoped TiO2 film in the electric field heating-treatment was studied by XRD and AFM. It is found that the crystals were homogeneous and the average crystal size was about 60 nm. Studies of photo-catalytic degradation show that the photo-catalytic activity of Ce4+, Sb3+-codoped TiO2 films heated to 500 ℃ in an applied electric field was higher.

Preparation of (Ti, Sn)O_2 Nano-Composite Photocatalyst by Supercritical Fluid Dry Combination Technology

A series of TiO2-SnO2 nano-sized composite photo-catalysts containing Sn (9.3%-30.1%) were prepared from TiCI4 and SnCl4·5H2O by using sol-gel, supercritical fluid dry and solid-phase reaction (SCFD) combination technology. Characterizations with X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) showed that, in addition to anatase type TiO2, a new active phase (Ti, Sn)O2 (with particle size of 2.0-4.3 nm) formed, and there were no SnO2 crystals observed in the range of the doping concentration studied. Photo-catalytic reaction of phenol was used as a model reaction to evaluate the catalytic activities of the obtained catalysts. Compared with pure TiO2 or Ti-Sn catalyst prepared with general sol-gel method, Ti-Sn nano-composite photo-catalyst thus obtained showed significant improvement in catalytic activity. The photo-catalytic degradation rate of phenol could reach as high as 93.5% after 7 h. The preparation conditions of the new phase (Ti, Sn)O2 were investigated and its catalytic mechanism was proposed. The photo-catalytic particles prepared using SCFD combination technology exhibited small particle size, large surface area and high activity.

Degradation of Residual Formaldehyde in Fabric by Photo-catalysis

The residual formaldehyde （HCHO） in fabric was degraded using photo-catalysis assisted by the compound catalyst of nano-TiO2 and nano-ZnO. The effects of several factors on the degradation, such as the composing of catalyst, irradiation time, pH value and the H2CHO concentration of the immersed solution were investigated. Results showed that H2CHO of the immersed solution had degraded 93% after 5 h irradiation, and the degradation ratio of formaldehyde could be improved and the aging of the fabric can be avoided with the addition of ZnO nanoparticles and pH value of the immersed-fibric solution. The fabric with residual formaldehyde about 1 800 μg/g can be efficiently treated to satisfy the China National Standard （GB/2912.1-1998） with the photo-catalytic degradation.

Micro-porous TiO2 thin films grown on surface of Ti substrate

Microporous titanium dioxide thin films have been grown on titanium plates by the micro-plasma oxidation method with different current densities (4, 6, 10 and 14 A/dm2). X-ray diffraction, scanning electronic microscopy and UV-Vis spectrophotometry were used to characterize the films. It is found that the films grown are microporous and consist of crystalline titanium dioxide. The micropore size and the content of anatase and rutile TiO2 phase increase with the applied voltage. The relatively higher degradation efficiency for rhodamine B is obtained in the film produced with a current density of 10 A/dm2.

Study on Modification of Nano-Sized Anatase Titanium Dioxide by Nitrogen-Plasma

The nano-sized particles of anatase titanium oxide （TiO2） were obtained by hydrolysis of titanium ester （TNB） in basic media and dehydrated in acid media. And then the anatase titanium oxide was treated with nitrogen plasma. The effect of nitrogen plasma treating time on the activity of photo-catalytic reduction of the Cr2O7^2- for sample obtained was investigated. The samples were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, Transmission Electron Microscope （TEM） and Ultraviolet （UV）. A peak of 396 eV in the N 1 s XPS spectra of sample obtained with nitrogen plasma treated TiO2 showed that nitrogen-doped titanium oxide （TiO2-zNx） has been obtained. The spectra of UV showed that the light absorption of TiO2-xNz obtained by nitrogen plasma treated TiO2 for 10min. had moved to the visible region. The picture of TEM and spectra of XRD indicated that the crystallographic forms and particle dimension had no apparent change for both the modified and the unmodified TiO2. When the TiO2 sample was treated for 7 min with nitrogen plasma, it exhibited best photo-catalytic activity.

First-principles investigation on N/C co-doped CeO2

The N and C doping effects on the crystal structures, electronic and optical properties of fluorite structure CeO2 have been investigated using the first-principles calculation. Co-doping these two elements results in the local lattice distortion and volume expansion of CeO2. Compared with the energy hand structure of pure CeO2, some local energy levels appear in the forbidden band, which may facilitate the light absorption. Moreover, the enhanced photo-catalytic properties of CeO2 were explained through the absorption spectra and the selection rule of the band-to-band transitions.

Root Extracts (<i>Gymnadenia orchidis</i>Lindl) Facilitated Rapid Synthesis of Fluorescent Silver Nanoparticles (Ag-NPs) for Various Biological Applications

One pot rapid and green bio-synthesis of stable fluorescent silver nanoparticles (Ag-NPs) from silver nitrate solution using root extract of Gymnadenia orchidis Lindlat at ambient temperature is demonstrated productively. Surface Plasmon resonance of the synthesized Ag-NPs was shown to occur at 439 nm and two sharp fluorescence peaks at 610 and 780 nm were observed. FTIR study publicized the presence of chemically functional groups in the root extract surrounding the Ag-NPs, acting as stabilizers. XRD and FESEM analysis revealed that Ag-NPs were face centred cubic structure being spherical in shape with an average particle size of 28 ± 2 nm (n = 100). The stability of Ag-NPs in neutral pH environment was confirmed by Zeta Potential (ζ) behaviour. The Ag-NPs showed superior antioxidant activity. The notable photo-catalytic activity of biosynthesized Ag-NPs attributed to the existence of some proteins, responsible for degradation of methylene blue dye. Furthermore, Ag-NPs were found to exhibit a significant antibacterial effect against gram positive Staphylococcus aureus (S. aureus) bacteria.

Preparation and Characterization of TiO₂Photocatalytic Thin Film and Its Compounds by Micro-Arc Oxidation Technique

Mesoporous TiO2 ceramic films have been prepared upon the Ti alloy substrate by the micro-arc oxidation (MAO) technology. To enhance the photo-catalytic property of the films, Eu2O3 particles were added into the electrolyte solution of Na2CO3/Na2SiO3. Scanning electron microscope (SEM), energy dispersive (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) are employed to characterize the modified films. Diffuse reflectance spectra (DRS) test, photo-generated current test and photo decomposition test are applied to evaluate the photo-catalytic property of the modified films. The results show that Eu2O3 transformed into one-dimensional (1-D) nano-wires embedded within the composite film, and the film has high photo-catalytic property.

Two-dimensional g-C_(3)N_(4)nanosheets-based photo-catalysts for typical sustainable processes

Graphitic carbon nitride(g-C_(3)N_(4))has been widely studied as a visible light responsive photocatalyst in recent years,due to its facile synthesis,low cost,high stability,and appropriate bandgap/band positions.In this review,we firstly introduce and compare various exfoliation approaches of bulk g-C_(3)N_(4)into ultrathin g-C_(3)N_(4)nanosheets.Then,many modification strategies of g-C_(3)N_(4)nanosheets are also reviewed,including heterojunction construction,doping,defect control,and structure design.Thereafter,the charge transfer mechanism in g-C_(3)N_(4)nanosheets based heterojunctions is present,e.g.,Z-scheme,S-scheme and other forms.Besides,the photocatalytic applications of g-C_(3)N_(4)nanosheets based photocatalysts are summarized including environmental remediation,energy generation and storage,organic synthesis,and disinfection.This review ends with a summary and some perspectives on the challenges and new directions in exploring g-C_(3)N_(4)nanosheets-based photocatalysts.

Hydrophilic and photocatalytic performances of lanthanum doped titanium dioxide thin films

Pure and La-doped TiO2 thin films were prepared on glass by sol-gel method using tetrabutyl titanate as Ti precursors. Their chemical composition, structure and properties were characterized by X-ray diffraction （XRD）, Fourier transform infrared （FT-IR）, UV-Visible spectrophotometer and optical contact angle measuring instrument, respectively. The results showed that the content of La was the key factor for hydrophilic and photocatalytic activity. LaTiO3 could be formed in La-doped TiO2 thin films, which caused the TiO2 lattice distortion and restrained the transition from anatase to rutile. By adding 0.3 wt.% La to the TiO2 thin films, the optimal hydrophilic character could be obtained and the contact angle was only 9.6~. La-doped TiO~ thin films could ex- pand the wavelength response range of TiO2, and thus increase the speed of the photocatalytic reaction. 92.02% of methylene blue was finally degraded when the concentration of La was 0.3 wt.%. The expressions of ln（CAo/CA） as functions of photocatalytic time were deduced which were well consistent with the experimental results.

Facile Synthesis of C3N4/Ag Composite Nanosheets as SERS Substrate for Monitoring the Catalytic Degradation of Methylene Blue

The C3N4/Ag composite nanosheets were facilely prepared via an in sire reduction process and Ag nanoparticles were well dispersed on the surface of C3N4 nanosheets. The unique two-dimensional structtlre and strong interactions between C3N4 nanosheets and Ag nanoparticles contributed the good surthce-enhanced Raman scattering（SERS） property due to the electromagnetic field enhancement. In addition, the as-prepared CaN4/Ag composite nanosheets could be used as catalysts or photocatalyst for the degradation of methylene blue（MB） in the presence of NaBH4 or under visible light. Therefore, a facile SERS monitoring of the catalytic and photocatalytic degradation process of MB and the determination of the reaction kinetics were developed.

Ilmenite:Properties and photodegradation kinetic on Reactive Black 5 dye

Ilmenite is natural mineral ore made up with titanium and iron mineral; including small portion of magnesium and manganese. To the best of our knowledge, photo-degradation of Reactive Black 5 dye（RB5） using ilmenite under solar irradiation is still lacking. In the present study, the physicochemical properties of ilmenite were characterized by using X-ray diffraction（XRD）, Scanning electron microscope（SEM）, BET and Raman Spectroscopy. Based on our results obtained, 73% solar-driven photo-degradation of RB 5 was successfully obtained when the catalyst loading increased up to 2.0 g/L for 20 min. In general,the photo-degradation of RB 5 by ilmenite followed first-order kinetics. The p H had a significant effect,with the most rapid degradation occurring at p H less than 7.

基于金属-有机框架同分异构体构建MOFs相结用以增强CO_(2)光还原活性

利用太阳能将CO_(2)光转化为化学燃料是前沿研究的热点.当前,科研的重点在于开发和优化各类光催化材料的性能.异质结构不仅用于增强无机半导体催化剂的活性,而且用于金属-有机框架(MOFs)光催化剂的构建.随着异质结技术的不断进步,新的相结概念应运而生.尽管关于无机半导体中的相结研究已取得一定进展,但是MOFs相结结构的探索尚处于起步阶段.本文中,我们成功设计并构建了一种具有卓越光催化CO_(2)还原性能的MOFs相结杂化材料.这种材料由具有高度连接性的卟啉配体(TCPP-Ni)与Zr6团簇紧密结合而成,在溶剂热反应条件下,PCN-222-Ni能够快速且均匀地成核.通过精准调控调节剂的用量,我们实现了同分异构体PCN-224-Ni在类似条件下较慢的晶体形成过程.最终制得的P@P杂化材料展现出高表面积、多孔性和卓越的结晶度.由于PCN-222-Ni和PCN-224-Ni之间的带隙匹配,光生载流子的分离和迁移得以促进,从而使P@P杂化材料展现出卓越的光还原CO_(2)性能.这一重大突破不仅标志着MOFs相结结构研究的重大进展,还拓宽了MOFs相结在CO_(2)光转化领域的应用前景.