A Novel 3D Metal Coordination Polymer Based on Tetranuclear Cobalt Cluster Building Blocks:Synthesis,Crystal Structure and Photocatalytic Property

A novel 3D MCP,[Co;（μ;-OH）(btc)（bmip）];(1,H;btc=1,3,5-benzenetricarboxylate acid,bmip=1,3-bis（2-methylimidazolyl）propane),was synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction,powder XRD,FT-IR,TGA and elemental analysis techniques.MCP 1 features a 3D framework based on tetranuclear Co（Ⅱ）clusters where the four cobalt ions are coplanar,and shows an unusual binodal（3,10）-connected topology.Furthermore,the photocatalytic experiment result indicates the degradation ratios of rhodamine B（RhB）reach 78.2%when MCP 1 acts as catalyst.

Ionothermal Synthesis, Crystal Structure and Photocatalytic Property of a New Cobalt Coordination Polymer

The reaction of flexible bis（imidazole） ligand and 1,2-bis（imidazol-l＇-yl）methane （bimm） with Co（Ⅱ） salt under ionothermal method resulted in the formation of a new coordination polymer {[Co（bimm）3]·（PF6）2}n （1）. X-ray single-crystal diffraction determination reveals that 1 crystallizes in the triclinic Pi space group, with α = 8.647（6）, b = 12.092（9）, c = 14.967（1 l） A, α = 88.912（8）, β = 81.199（8）, ）, = 89.395（8）°, V= 1546 （2） A3, Z = 2, Mr = 793.39, Dc= 1.704 Mg/m3,μ = 0.768 mm-1 F（000） = 798, the final R = 0.0626 and wR = 0.1634 for 4319 observed reflections with I〉 2σ（I）. In compound 1, the Co（lI） ion is connected to another Co（ll） by two bimm ligands to form 1D double chains which are further linked by bimm ligands to form a 2D wavelike layer. Topologically, the structure of 1 represents a uninodal 2D 4-connected sq1/Shubnikov tetragonal plane net. Moreover, thermogravimetric analyses and photocatalytic property for 1 have also been investigated.

Synthesis and Photocatalytic Property of the ZrO_2/TiO_2 Pillared Laponite

The ZrO2/TiO2 pillared laponite （Ti-Zr-lap） photocatalysts were prepared with intercalation reaction by supercritical fluid drying （SCFD）,and characterized by XRD,TEM,SEM and BET surface area analysis,and the photocatalytic properties of Ti-Zr-lap were investigated by degradation of azo dye acid red B （ARB）.The results showed that the ZrO2/TiO2 pillared structures in laponite could be formed,with the mass fraction of （Zr4＋＋Ti4＋）/laponite （Xm） increasing,the basal spacing and the BET surface area of Ti-Zr-lap significantly increased.The Ti-Zr-lap used as photocatalyst had the advantages of stable and porous layered structure,large surface area with the anatase type TiO2.Compared with the Ti-Zr-lap dried by air drying,the Ti-Zr-lap dried by SCFD showed better photocatalytic property which was very close to that of P25 TiO2.Using the Ti-Zr-lap as photocatalyst with the optimum Xm of 0.16 and the calcination temperature of 500 ℃,under the conditions of the initial concentration of ARB 20 mg/L,photocatalyst concentration of 1.5 g/L and irradiation time 60 min,the decoloring rate of ARB could achieve 98.3%,indicating that the Ti-Zr-lap had excellent photocatalytic property.

Regulating Electron-Hole Separation to Promote the Photocatalytic Property of BiOBr_1−xI_x/BiOBr Local Distorted Hierarchical Microspheres

In this work, hierarchical BiOBr1−xIx/BiOBr heterojunction photocatalyst with a microsphere morphology was synthesized by a facile solvothermal process. It demonstrated that the local structure of the photocatalysts was highly distorted due to the substitution of bromide ions by iodine ions. The photocatalytic properties were evaluated by the photodecomposition of aqueous phenol solution under visible-light irradiation. The results indicated that all the composite photocatalysts exhibited high photocatalytic activity. In particularly, the BiOBr1−xIx/BiOBr (x = 0.25) sample exhibited over 92% degradation efficiency of phenol within 150 min, which is 24.6 and 3.08 fold enhancement in the photocatalytic activity over the pure phased BiOBr and BiOI, respectively. Moreover, this excellent photocatalytic property can be expanded to other colorless organic contaminants, verifying the common applicability of BiOBr1−xIx/BiOBr (x = 0.25) as an excellent visible-light photocatalyst for organics decomposition. The significant improvement in the photocatalytic activity can be explained by the high efficiency of charge separation due to the enhancement in the internal electric fields and band match that comes from the local structure distortion. This work provides valuable information for the design of highly active photocatalysts toward the environmental remediation.

Appreciable Enhancement of Photocatalytic Performance for N-doped SrMoO_(4) via the Vapor-thermal Method

A series of nitrogen-doped SrMoO_(4) with different Sr/N mole ratio (R=0,0.05,0.10,0.15,0.20,0.40,and 0.60) were synthesized using urea as the N source via the vapor-thermal method.The photocatalytic degradation ability of all samples was evaluated using methylene blue (MB) as a target contaminant.The band gaps of N-doped samples are all higher than that of pristine ones,which is only 3.12 eV.BET specific surface area S_(BET) and pore volume are increased due to the N doping.And the greater increase of S_(BET),the faster the photodegradation speed of methylene blue on SrMoO_(4).More specifically,the degradation efficiency of MB is improved up to 87%in 100 min.

Synthesis and photocatalytic property of Ce-doped SnO_2

Pure SnO2 and Ce-doped(1%,4%,7%,10% in mass ratio) SnO2 powders were prepared by a simple sol-gel method.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the 7% Ce-doped sample has a particle size of 0.1-0.3 μm with a narrow particle size distribution while the pure SnO2 was consisted of large agglomerated particles with a diameter up to several micrometers.When used as the catalyst to degrade methyl orange(MO),the 7% Ce-doped sample showed best photocatalytic property.These properties can be attributed to the large surface area and small particle size of the 7% Ce-doped sample.

LDH-based nanomaterials for photocatalytic applications:A comprehensive review on the role of bi/trivalent cations, anions,morphology, defect engineering, memory effect, and heterojunction formation

Using sunlight to drive chemical reactions via photocatalysis is paramount for a sustainable future.Among several photocatalysts,employing layered double hydrides(LDH) for photocatalytic application is most straightforward and desirable owing to their distinctive two-dimensional(2D) lamellar structure and optical attributes.This article reviews the advancements in bimetallic/trimetallic LDHs and various strategies to achieve high efficiency toward an outstanding performing photocatalyst.Firstly,the tuning of LDH components that control the electro nic and structural properties is explained.The tu ning obtained through the adoption,combination,and incorporation of different cations and anions is also explained.The progress of modification methods,such as the adoption of different morphologies,delamination,and defect engineering towards enhanced photocatalytic activities,is discussed in the mainstream.The band engineering,structural characteristics,and redox tuning are further deliberated to maximize solar energy harvesting for different photocatalytic applications.Finally,the progress obtained in forming hierarchical heterostructures through hybridization with other semiconductors or conducting materials is systematically disclosed to get maximum photocatalytic performance.Moreover,the structural changes during the in-situ synthesis of LDH and the stability of LDH-based photocatalysts are deliberated.The review also summarizes the improvements in LDH properties obtained through modification tactics and discusses the prospects for future energy and environmental applications.

Mesh-Like Bi2MoO6 with Enhanced and Stable Visible Light Photocatalytic Activity

Mesh-like Bi2MoO6 product was successfully synthesized by a hydrothermal method without using any surfactant or template. The pH value played an important role in the formation of this morphology. The as-prepared mesh-like Bi2MoO6 sample exhibited excellent visible-light-driven photocatalytic e ciency. The photocatalytic activity of the mesh-like Bi2MoO6 sample was much higher than that of bulk Bi2MoO6 sample prepared by solid-state reac-tion. Di erence in the photocatalytic activities of the mesh-like Bi2MoO6 sample and bulk Bi2MoO6 sample was further investigated.

Fabrication and photocatalytic properties of Cu_2S/T-ZnO_w heterostructures via simple polyol process

The Cu2S/tetrapod-like ZnO whisker（T-ZnOw） heterostructures were successfully synthesized via a simple polyol process employing the poly（vinyl pyrrolidone）（PVP） as a surfactant.The as-prepared heterostructures were characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,X-ray photoelectron spectroscopy（XPS） and Fourier transform infrared（FTIR）.The photocatalytic properties of Cu2S/T-ZnOw nanocomposites synthesized with different PVP concentrations were evaluated by photodegradation of methyl orange（MO） under UV irradiation.The results show that the Cu2S/T-ZnOw nanocomposites exhibit remarkable improved photocatalytic property compared with the pure T-ZnOw.The sample prepared with 3.0 g/L PVP shows an excellent photocatalytic property and the highest photodegradation rate of MO is 97% after UV irradiation for 120 min.Besides,the photocatalytic activity of the photocatalyst has no evident decrease even after four cycles,which demonstrates that the Cu2S/T-ZnOw photocatalyst exhibits an excellent photostability.Moreover,the photocatalytic mechanism of the Cu2S/T-ZnOw nanocomposites was also discussed.

Enhanced photocatalytic properties of hierarchical nanostructured TiO_2 spheres synthesized with titanium powders

Using Ti powder as reagent, TiO 2 nanoneedle/nanoribbon spheres were prepared via hydrothermal method in NaOH solution. The samples were characterized by field emission scanning electron microscopy （FESEM）, transmission electron microscopy （TEM） with selected area electron diffraction （SAED）, X-ray diffraction （XRD）, and UV-visible light absorption spectrum. The results indicate that the growth orientations of the crystals are influenced by the hydrothermal temperature and NaOH concentration. The diameter of the nanoneedle spheres and nanoribbon spheres （40 50 μm） are almost the same as that of Ti powders. TiO 2 nanoneedle/nanoribbon sphere powders are anatase after heat treatment at 450 °C for 1 h. Furthermore, methyl orange was used as a target molecule to estimate the photocatalytic activity of the specimens. Under the same testing conditions, the photocatalytic activities of the products decrease in the following order： TiO 2 nanoneedle sphere, TiO 2 nanoribbon sphere and P25.

Enhanced Photoelectric Property of Mo-C Codoped TiO2 Films Deposited by RF Magnetron Cosputtering

Mo-C codoped TiO2 films were prepared by RF magnetron cosputtering. Ultraviolet-visible spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray Analysis and X-Ray Diffraction were used to study the influences of codoping on energy gap, surface morphology, valence states of elements, ions content and crystal structure, respectively. The concentration of photogenerated carriers was measured by studying photocurrent density, while catalytic property was evaluated by observing degradation rate of methylene blue under visible light. A Mo-doped TiO2 film, whose content of Mo had been optimized in advance, was prepared and later used for subsequent comparisons with codoped samples. The result indicates that Mo-C codoping could curtail the energy gap and shift the absorption edge toward visible range. Under the illumination of visible light, codoped TiO2 films give rise to stronger photocurrent due to smaller band gaps. It is also found that Mo, C codoping results in a porous surface, whose area declines gradually with increasing carbon content. Carbon and Molybdenum doses were delicately optimized. Under the illumination of visible light, sample doped with 9.78at% carbon and 0.36at% Mo presents the strongest photocurrent which is about 8 times larger than undoped TiO2 films, and about 6 times larger than samples doped with Mo only.

Construction of a Photocatalytic Cobalt(Ⅱ) Coordination Polymer with 4-Connected Diamond Topology

A novel cobalt（Ⅱ） coordination polymer, [Co（tdc）（bpmp）（H2O）]n（1）, was hydrothermally synthesized using 2,5-thiophenedicarboxylate（tdc） and bis（4-pyridylmethyl）piperazine（bpmp） ligand as the organic linkers. X-ray single-crystal diffraction determination reveals that 1 crystallizes in the monoclinic Cc space group, with a = 18.836（2）, b = 5.9540（7）, c = 20.414（2） A, β = 97.4300（10）°, V = 2270.1（5） A3, Z = 4, Mr = 515.44, Dc = 1.508 Mg/m^3, μ = 0.890 mm-1, F（000） = 1068, the final R = 0.0263 and w R = 0.0665 for 3714 observed reflections with I 2σ（I）. In compound 1, the Co（Ⅱ） ions are connected by tdc2- anions to form a 1D double chain, and such chains are further linked by bpmp ligands to form a three-dimensional（3D） structure. Topologically, the structure of 1 represents a uninodal 3D dia（6^6） topology. What＇s more, powder X-ray diffraction patterns and photocatalytic property for 1 have also been investigated.

One-step hydrothermal synthesis of Sn-doped α-Fe_(2)O_(3) nanoparticles for enhanced photocatalytic degradation of Congo red

We report on the synthesis of Sn-doped hematite nanoparticles(Sn-α-Fe_(2)O_(3) NPs)by the hydrothermal method.The prepared Sn-α-Fe_(2)O_(3) NPs had a highly pure and well crystalline rhombohedral phase with an average particle size of 41.4 nm.The optical properties of as-synthesizedα-Fe_(2)O_(3) NPs show a higher bandgap energy(2.40-2.57 eV)than that of pure bulkα-Fe_(2)O_(3)(2.1 eV).By doping Sn intoα-Fe_(2)O_(3) NPs,the Sn-doped hematite was observed a redshift toward a long wavelength with in-creasing Sn concentration from 0%to 4.0%.The photocatalytic activity of Sn-dopedα-Fe_(2)O_(3) NPs was evaluated by Congo red(CR)dye degradation.The degradation efficiency of CR dye using Sn-α-Fe_(2)O_(3) NPs catalyst is higher than that of pureα-Fe_(2)O_(3) NPs.The highest degradation efficiency of CR dye was 97.8%using 2.5%Sn-dopedα-Fe_(2)O_(3) NPs catalyst under visible-light irradi-ation.These results suggest that the synthesized Sn-dopedα-Fe_(2)O_(3) nanoparticles might be a suitable approach to develop a photocatalytic degradation of toxic inorganic dye in wastewater.

Enhanced Photocatalytic Properties of Silver Oxide Loaded Bismuth Vanadate

In this work, BiV04 powders were synthesized by a sol-gel method, and the BiV04 gels with different calcination temperature were investigated by X-ray diffraction （XRD）. Absorption range and band gap energy, which are respon- sible for the observed photocatalyst behavior, were investigated by UV/vis diffuse reflectance spectroscopy （DRS） for pure and silver oxide loaded BiV04. Pbotocatalytic properties of the prepared samples were examined by studying the degradation of the methyl orange. When using NaCI02 as an electron acceptor, the possible photocatalytic mech- anism has been discussed by photocatalytic reactions. With the help of electron acceptor, the results show clearly that the BiV04 loaded silver oxide exhibited superior photocatalytic activity in simulated dye wastewater treatment.

Synthesis,Structure,Photoluminescence and Photocatalytic Properties of a New Cd(Ⅱ)Metal-organic Framework Based on 1,4-Di(2,6-dimethyl-3,5-dicarboxypyridyl)benzene

A new 3D coordination polymer, [Cd2（L）（bpb）2]n（1, H4L = 1,4-di（2,6-dimethyl-3,5-dicarboxypyridyl） benzene, bpb = 1,4-bis（4-pyridyl） benzene, has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, TGA, IR spectroscopy and UV-Vis spectrum. Complex 1 crystallizes in orthorhombic, space group C2221, with a = 10.9393（12）, b = 20.900（3）, c = 20.027（2） A, β = 90°, V = 4578.9（9） A^3, Dc = 41.668 Mg/cm^3, Mr = 1149.74, F（000） = 2312.0, μ = 0.996 mm^（–1）, Z = 4, the final R = 0.0316 and wR = 0.0786 for 4271 observed reflections with I 〉 2σ（I）. Structural analysis shows that 1 possesses a 3D network based on the 2D layer bridged by L^4-ligands, while the 2D layers are composed of the adjacent 1D chains joined by L^4-ligand. The photoluminescent investigation indicates that one broad emission band with the maximum of 445 nm can be observed in 1. Moreover, compound 1 has high photocatalytic degradation effects on methylene blue under UV irradiation.

Influence of Cadmium Doping on Structural, Optical, electrical and Photocatalytic Properties of TiOz Thin Films Prepared by Spray Pyrolysis Technique

Undoped and doped cadmuim titanium oxide thin films at different percentage （1, 3, 4, and 5）% were fabricated by spray pyrolysis by using a solution of titanium tetrachloride and ethyl alcohol. The films have been deposited on heated quartz substrates at 623 K. After annealing for 120 min at 823 K, the initially amorphous films became polycrystalline with a predominant anatase structure and average crystallite sizes depending on dopant Cd concentration. Atomic force microscope （AIM） results show that the addition of the Cd to TiO2 thin films become smooth. Optical study shows the optical band gap, and transmission has been increasing with increasing doping concentration in TiO2 thin films. The electrical resistivity is decreases with increasing doping concentration Cd in TiO2 thin films could be attributed to the increasing charge concentration. Photocatalytic activity of the TiO2 films were studied by monitoring the degradation of aqueous methylene blue under UV light irradiation and was observed that increasing doping concentration had good photocatalytic activity which was explained as due to the structural and morphological properties of the films.

Anisotropy of Photocatalytic Properties in Nanostructured Photocatalysts

Energy band engineering and the nature of surface/interface of a semiconductor play a significant role in searching high efficiency photocatalysts. Actually, the active facets, morphology controlling, especially the exposed facets modulation of photocatalysts during preparation are very desirable. In order to achieve high photocatalytic performance, intrinsic mechanism of such anisotropic properties should be fully considered. In this review, we mainly emphasis on the latest research developments of several extensively investigated photocatalysts and their anisotropic photocatalytic properties, as well as the correlation between effective masses anisotropy and photocatalytic properties. It will be helpful to understand the photocatalytic mechanism and promote rational development of photocatalyst for wide applications.

Photoelectrocatalytic principles for meaningfully studying photocatalyst properties and photocatalysis processes:From fundamental theory to environmental applications

Photocatalysis is critically important for environmental remediation and renewable energy technologies.The ability to objectively characterize photocatalyst properties and photocatalysis processes is paramount for meaningful performance evaluation and fundamental studies to guide the design and development of high-performance photocatalysts and photocatalysis systems.Photocatalysis is essentially an electron transfer process,and photoelectrocatalysis(PEC)principles can be used to directly quantify transferred electrons to determine the intrinsic properties of photocatalysts and photocatalysis processes in isolation,without interference from counter reactions due to physically separated oxidation and reduction half-reactions.In this review,we discuss emphatically the PEC-based principles for characterizing intrinsic properties of photocatalysts and important processes of photocatalysis,with a particular focus on their environmental applications in the degradation of pollutants,disinfection,and detection of chemical oxygen demand(COD).An outlook towards the potential applications of PEC technique is given.

Visible-light Driven Photocatalysts: Al-, Ga-, and In-doped Monoclinic BiVO_4

The first-principles calculations were performed to investigate the stability, band structure, density of states and redox potential of Al-, Ga-, and In-doped monoclinic BiVO4（mBiVO4）. The calculated formation energies show that Al-doped mBiVO4 inducing an O vacancy is energetically favorable with a smaller defect formation value. With the incorporation of Al, Ga, and In, the band gap of the doped systems will be narrowed in the order of Al-doped 〈 Ga-doped 〈 In-doped mBiVO4, which is beneficial for the response to the visible light. And the substitution of an Al or Ga for a V atom will significantly enhance the reducibility of mBiVO4, improving the efficiency of H2 evolution from H2 O. Our results show that the photocatalytic activity of mBiVO4 can be modulated by substitutional doping of Al, Ga, and In.

Interfacial defect engineering and photocatalysis properties of hBN/MX_(2)(M=Mo,W,and X=S,Se)heterostructures

Van der Waals(VDW)heterostructures have attracted significant research interest due to their tunable interfacial properties and potential applications in many areas such as electronics,optoelectronic,and heterocatalysis.In this work,the influences of interfacial defects on the electronic structures and photocatalytic properties of hBN/MX_(2)(M=Mo,W,and X=S,Se)are studied using density functional theory calculations.The results reveal that the band alignment of hBN/MX_(2) can be adjusted by introducing vacancies and atomic doping.The type-Ⅰband alignment of the host structure is maintained in the heterostructure with n-type doping in the hBN sublayer.Interestingly,the band alignment changed into the type-Ⅱheterostructrue due to V_(B) defect and p-type doping is introduced into the hBN sublayer.This can conduce to the separation of photo-generated electron-hole pairs at the interfaces,which is highly desired for heterostructure photocatalysis.In addition,two Z-type heterostructures including h BN(BeB)/MoS_(2),hBN(Be_(B))/MoSe_(2),and hBN(V_(N))/MoSe_(2)are achieved,showing the decreasing of band gap and ideal redox potential for water splitting.Our results reveal the possibility of engineering the interfacial and photocatalysis properties of hBN/MX_(2) heterostructures via interfacial defects.