Photocatalytic Activity of Hierarchical Flower-Like TiO_(2) Superstructures with Dominant {001} Facets

The fabrication of well defined hierarchical structures of anatase TiO_(2) with a high percentage of reactive facets is of great importance and challenging.Hierarchically flower-like TiO_(2) superstructures(HFTS)self-assembled from anatase TiO_(2) nanosheets with exposed{001}facets(up to 87%)were synthesized by a simple alcohothermal strategy in a HF-H_(2)O-C_(2)H_(5)OH mixed solution using titanate nanotubes as precursor.The samples were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and N2 adsorption-desorption isotherms.The photocatalytic activity was evaluated by the photocatalytic oxidation decomposition of acetone in air and methyl orange in aqueous solution under UV illumination.The photocatalytic activity of HFTS was much higher than that of commercial Degussa P25 and tabular-shaped anatase TiO_(2) obtained using pure water as the synthesis medium.The enhancement in photocatalytic activity was related to several factors,including the hierarchically porous structure,exposed{001}facets,and increased light harvesting ability.The HFTS was also of interest for use in solar cells,photocatalytic H_(2) production,optoelectronic devices,sensors,and catalysis.

Synthesis and Optimization of TiO_(2)/Graphene with Exposed {001} Facets Based on Response Surface Methodology and Evaluation of Enhanced Photocatalytic Activity

Response surface methodology(RSM)was employed to optimize the control parameters of TiO_(2)/graphene with exposed{001}facets during synthesis,and its enhanced photocatalytic activities were evaluated in the photodegradation of toluene.Experimental results were in good agreement with the predicted results obtained using RSM with a correlation coefficient(R^(2))of 0.9345.When 22.06 mg of graphite oxide(GO)and 2.09 mL of hydrofluoric acid(HF)were added and a hydrothermal time of 28 h was used,a maximum efficiency in the degradation of toluene was achieved.X-ray diffraction(XRD),transmission electron microscopy(TEM),and scanning electron microscopy(SEM)were employed to characterize the obtained hybrid photocatalyst.The electron transferred between Ti and C retarded the combination of electron–hole pairs and hastened the transferring of electrons,which enhanced the photocatalytic activity.

Pt/TiO_(2) Nanosheets Array Dominated by {001} Facets with Enhanced Photocatalytic Activity

{001}facets dominated single crystalline anatase TiO_(2) nanosheet array(TNSA)was synthe-sized through an optimized organic solvothermal route on uorine-doped tin oxide substrate.The field emission scanning electron microscopy images and X-ray diffraction patterns re-vealed that the{001}synthesized facets dominated TNSA exhibited much higher orientation than that synthesized by hydrothermal route.The TNSAs were loaded with Pt nanoparti-cles in uniformly size by using a photodecomposition method,which were further con rmed by high resolution transmission electron microscopy(HRTEM).The HRTEM images also revealed that Pt nanoparticles preferred to deposit on{001}facets.With loading of Pt nanoparticles,the optical absorbance was significantly enhanced,while the photolumines-cence(PL)was inhibited.The photocatalytic activity of TNSA was signi cantly improved by Pt loading and reached the maximum with optimal amount of Pt loading.The optimal amount of Pt on{001}facets is far less than that on TiO_(2) nanoparticles,which may be attributed to the specific atom structure of reactive{001}facets.

TiO_(2) nanosheets with exposed {001} facets for photocatalytic applications

TiO_(2) nanosheets with highly reactive{001}facets({001}-TiO_(2))have attracted great attention in the fields of science and technology because of their unique properties.In recent years,many efforts have been made to synthesize{001}-TiO_(2) and to explore their applications in photocatalysis.In this review,we summarize the recent progress in preparing{001}-TiO_(2) using different techniques such as hydrothermal,solvothermal,alcohothermal,chemical vapor deposition(CVD),and sol gel-based techniques.Furthermore,the enhanced efficiency of{001}-TiO_(2) by modification of carbon materials,surface deposition of transition metals,and non-metal doping is reviewed.Then,the applications of{001}-TiOR-based photocatalysts in the degradation of organic dyes,hydrogen evolution,carbon dioxide(CO_(2))reduction,bacterial disinfection,and dye-sensitized solar cells are summarized.We believe this entire review on TiO_(2) nanosheets with{001}facets can further inspire researchers in associated fields.

Prolonging charge-separation states by doping lanthanide-ions into {001}/{101} facets-coexposed TiO_(2) nanosheets for enhancing photocatalytic H_(2) evolution

Ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets have attracted considerable attention because of their high photocatalytic activity.However,the charge-separated states in the TiO_(2)nanosheets must be extended to further enhance their photocatalytic activity for H_(2)evolution.Herein,we present a successful attempt to selectively dope lanthanide ions into the{101}facets of ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets through a facile one-step solvothermal method.The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO_(2)nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra.Upon simulated sunlight irradiation,we observed a 4.2-fold enhancement in the photocatalytic H_(2)evolution activity of optimal Yb^(3+)-doped TiO_(2)nanosheets compared to that of their undoped counterparts.Furthermore,when Pt nanoparticles were used as cocatalysts to reduce the H_(2)overpotential in this system,the photocatalytic activity enhancement factor increased to 8.5.By combining these results with those of control experiments,we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H_(2)evolution activity of lanthanide-doped TiO_(2)nanosheets with coexposed{001}/{101}facets.

{001} facets dominated anatase TiO_(2) : Morphology, formation/etching mechanisms and performance

Controllable growth of anatase TiO_(2)crystals with exposed high reactive crystal facets has aroused great attention in the fields of science and technology due to their unique structure-dependent properties.Recently,much effort has been paid to synthesize anatase TiO_(2)crystals with exposed high reactive{001}facets.Herein,we review the recent progress in synthesizing{001}facets dominated anatase TiO_(2)crystals with different morphologies by various synthetic methods.Furthermore,our review is mainly focused on the formation/etching mechanisms of{001}facets dominated anatase TiO_(2)crystals based on our and other studies.The extensive application potentials of the anatase TiO_(2)crystals with exposed{001}facets have been summarized in this review such as photocatalysis,photoelectrocatalysis,solar energy conversion,lithium ion battery,and hydrogen generation Based on the current studies,we give some perspectives on the research topic.We believe that this comprehensive review on anatase TiO_(2)crystals with high reactive{001}facets can further promote the relative research in this field.

Effect of defects in TiO_(2) nanoplates with exposed {001} facets on the gas sensing properties

The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excellent gas-sensing properties.In this paper,TiO_(2) nanoplates with defective{001}facets were synthesized by chemical etching via one-step hydrothermal method.We carefully explored the gas-sensing performance of TiO_(2) nanoplates with defective and complete{001}facets towards acetone.The results show that the sensing response of TiO_(2) nanoplates with complete{001}facets is 70%higher than that of defective TiO_(2) nanoplates,which proves that the{001}facets plays a vital role in improving the gas sensing performance of TiO_(2).It is speculated that the poor gas sensitivity of defective TiO_(2) can be contributed to fewer adsorption sites and blocked electron transfer.This work presents a more direct evidence for explaining the important role of the complete{001}crystal facets in high sensitivity of TiO_(2) and also provides a new insight for preparing high sensitivity sensing materials.

Mesocrystalline TiO_(2) nanosheet arrays with exposed {001} facets: Synthesis via topotactic transformation and applications in dye-sensitized solar cells

A facile,fluorine-free approach for synthesizing vertically aligned arrays of mesocrystaUine anatase TiO_(2) nanosheets with highly exposed{001}facets was developed through topotactic transformation.Unique mesocrystalline{001}-faceted TiO_(2) nanosheet arrays vertically aligned on conductive fluorine-doped tin oxide glass were realized through topotactic conversion from single-crystalline precursor nanosheet arrays based on lattice matching between the precursor and the anatase crystals.The morphology and microstructure of the{001}-faceted TiO_(2) nanosheets could be readily modulated by changing the reactant concentration and annealing temperature.Owing to enhanced dye adsorption,reduced charge recombination,and enhanced light scattering arising from the exposed{001}facets,in addition to the advantageous features of low-dimensional structure arrays(e.g.,fast electron transport and efficient charge collection),the obtained TiO_(2) nanosheet arrays exhibited superior performance when they were used as anodes for dye-sensitized solar cells(DSSCs).Particularly,{001}-faceted TiO_(2) nanosheet arrays-15μm long annealed at 500℃showed a power conversion efficiency of 7.51%.Furthermore,a remarkable efficiency of 8.85%was achieved for a DSSC based on doubleqayered TiO_(2) nanosheet arrays-35μm long,which were prepared by conversion from the precursor nanoarrays produced via secondary hydrothermal growth.

Self-assembly of nitrogen-doped TiO_(2) with exposed {001} facets on a graphene scaffold as photo-active hybrid nanostructures for reduction of carbon dioxide to methane

Tailored synthesis of well-defined anatase TiO_(2)-based crystals with exposed{001}facets has stimulated incessant research interest worldwide due to their scientific and technological importance.Herein,anatase nitrogen-doped TiO_(2)(N-TiO_(2))nanoparticles with exposed{001}facets deposited on the graphene(GR)sheets(N-TiO_(2)-001/GR)were synthesized for the first time via a one-step solvothermal synthetic route using NH4F as the morphology-controlling agent.The experimental results exemplified that GR was uniformly covered with anatase N-TiO_(2) nanoparticles(10-17 nm),exposing the{001}facets.The percentage of exposed{001}facets in the N-TiO_(2)-001/GR nanocomposites was calculated to be ca.35%.Also,a red shift in the absorption edge and a strong absorption in the visible light range were observed due to the formation of Ti-O-C bonds,resulting in the successful narrowing of the band gap from 3.23 to 2.9 eV.The photocatalytic activities of the as-prepared photocatalysts were evaluated for CO_(2) reduction to produce CH,in the presence of water vapor under ambient temperature and atmospheric pressure using a low-power 15 W energy-saving daylight lamp as the visible light source--in contrast to the most commonly employed high-power xenon lamps--which rendered the process economically and practically feasible.Among all the studied photocatalysts,the N-TiO_(2)-001/GR nanocomposites exhibited the greatest CH4 yield of 3.70 p-mol'gcatalyst 1,approxi-mately 11-fold higher activity than the TiO_(2)-001.The enhancement of photocatalyfic performance was ascribed to the effective charge anti-recombination of graphene,high absorption of visible light region relative to the{101}facets.and high catalytic activity of{001}facets.

Enhanced photocatalytic properties of N–P co-doped TiO_(2) nanosheets with {001} facets

Nitrogen(N)and phosphorus(P)co-doped anatase TiO_(2) nanosheets were realized by low-temperature self-doping N-TiO_(2) followed by high-temperature P doping with foreign precursor.It is found that P doping process can maintain good TiO_(2) nanosheets morphology with exposed{001}facets.Chemical state of dopants indicates that N and P atoms replace O on O sites in TiO_(2) lattice.Compared with pure TiO_(2) and N-doped TiO_(2),N-P codoped TiO_(2) nanosheets exhibits stronger optical absorption and higher degradation rate of dye molecules in visible light regime.The enhanced photocatalytic properties are attributed to two factors.On one hand,N-P co-doping can effectively reduce band gap of TiO_(2) from 3.20 to 2.48 eV,leading to an enhancement of the absorption in visible light regime.On the other hand,the presence of exposed{001}facets of TiO_(2) nanosheets can induce the effective sepa-ration of photogenerated electrons and holes in reaction.

Synthesis of visible-light-driven TiO_(2) yolk-shell spheres with {001} facets dominated mesoporous shells

Anatase phase visible-light-driven TiO_(2) yolk-shell spheres with the size of ca.1-2 um have been synthesized with the combination of solvothermal and heat treatment method.XRD,SEM,TEM,XPS,and PL analysis were used to examine structure and properties of the photocatalyst.The N species and Ti3+centers introduced into the as-prepared photocatalyst can enhance the visible light absorption significantly.The mesoporous shell of the prepared photocatalyst,which promotes the pollutant adsorption ability,consists of the high-reactive[001]facets dominated nanocrystals.Due to the unique structure,it is also observed that the as-prepared visible-light-driven TiO_(2) yolk-shell spheres exhibit a sunerinr nhnrncatalvtic activity for organic dyes decomposition than the well-known P25.

One-step synthesized SO_4^(2-)-TiO_2 with exposed(001) facets and its application in selective catalytic reduction of NO by NH_3

A sample of sulfated anatase TiO2 with high‐energy(001)facets(TiO2‐001)was prepared by a simple one‐step hydrothermal route using SO42-as a morphology‐controlling agent.After doping ceria,Ce/TiO2‐001 was used as the catalyst for selective catalytic reduction(SCR)of NO with NH3.Compared with Ce/P25(Degussa P25 TiO2)and Ce/P25‐S(sulfated P25)catalysts,Ce/TiO2‐001 was more suitable for medium‐and high‐temperature SCR of NO due to the high surface area,sulfation,and the excellent properties of the active‐energy(001)facets.All of these facilitated the generation of abundant acidity,chemisorbed oxygen,and activated NOx‐adsorption species,which were the important factors for the SCR reaction.

The preparation of nitrogen-doped TiO_2 nanocrystals with exposed {001} facets and their visible-light photocatalytic performances

Anatase TiO2with exposed{001}facets has been deepgoingly studied for optimizing its photocatalytic activity.In this study,we synthesized N-doped TiO2 nanocrystals with exposed{001}facets by sol–gel method and solvothermal method,respectively.The physical and chemical properties of as-synthesized samples,such as morphology,crystal phase,surface elements composition,porous structure,specific surface area,and optical response,were characterized in detail.The photocatalytic performances of all samples were evaluated by photocatalytic decoloration of methylene blue under visible-light irradiation(k[420 nm).The results showed that the as-prepared samples present high visible-light photocatalytic performances,which can be ascribed to the excellent crystallization,the enhancement of absorbance in the visible-light region,and the strong adsorption performance,and calcination treatment is helpful to further improve the visible-light photocatalytic performance of N-doped TiO2 nanocrystals with exposed{001}facets.

In-situ assembly of TiO2 with high exposure of(001)facets on three-dimensional porous graphene aerogel for lithium-sulfur battery

Resulting from the development of electric vehicles,high energy-density Li-S batteries have recently attracted ever-increasing attentions worldwide.However,continuous dissolution of cathodic sulfur and followed shuttle effect of polysulfides lead to very limited service lifetime for currently-applied Li-S batteries.Herein,a 3 D porous graphene aerogel(GA)decorated with high exposure of anatase TiO2(001)nanoplatelets is proposed as robust host to immobilize cathodic sulfur.Compared with commonly used TiO2(101)nanoparticles,the Ti O2(001)nanoplatelets have highly matched lattices with graphene(002)nanosheets,thus facilitating the electronic transfer.The in-site assembled TiO2@GA host exhibits superior sulfur-immobilized capability,which cannot only entrap sulfur by physical confinement,but also capture dissoluble sulfurous species by chemical bonding.The fabricated S@TiO2@GA cathode shows excellent electrochemical performance with high discharge capacity,superior rate capability,and durable cycling stability as well,supposed to be a promising cathode for high-performance Li-S battery applications.

Surface deterioration dependent on the crystal facets of spinel LiNi_(0.5)Mn_(1.5)O_(4) cathode active material

The spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode active materials(CAMs)are considered a promising alternative to commercially available cathodes such as layered and polyanion oxide cathodes,primarily due to their notable safety and high energy density,particularly in their single-crystal type.Nevertheless,the industrial application of the LNMO CAMs is severely inhibited due to the interfacial deterioration and corrosion under proton-rich and high-voltage conditions.This study successfully designed and synthesized two typical types of crystal facets-exposed single-crystal LNMO CAMs.By tracking the electrochemical deterioration and chemical corrosion evolution,this study elucidates the surface degradation mechanisms and intrinsic instability of the LNMO,contingent upon their crystal facets.The(111)facet,due to its elevated surface energy,is found to be more susceptible to external attack compared to the(100)and(110)facets.Our study highlights the electrochemical corrosion stability of crystal plane engineering for spinel LNMO CAMs.

Surface Modification of (001) Facets Dominated TiO2 with Ozone for Adsorption and Photocatalytic Degradation of Gaseous Toluene

This study investigated the positive effect of surface modification with ozone on the photocatalytic performance of anatase TiO2 with dominated（001） facets for toluene degradation.The performance of photocatalyst was tested on a home-made volatile organic compounds degradation system. The ozone modification, toluene adsorption and degradation mechanism were established by a combination of various characterization methods, in situ diffuse reflectance infrared fourier transform spectroscopy, and density functional theory calculation.The surface modification with ozone can significantly enhance the photocatalytic degradation performance for toluene. The abundant unsaturated coordinated 5 c-Ti sites on（001）facets act as the adsorption sites for ozone. The formed Ti–O bonds reacted with H2O to generate a large amount of isolated Ti5 c-OH which act as the adsorption sites for toluene,and thus significantly increase the adsorption capacity for toluene. The outstanding photocatalytic performance of ozone-modified TiO2 is due to its high adsorption ability for toluene and the abundant surface hydroxyl groups, which produce very reactive OH·radicals under irradiation. Furthermore, the O2 generated via ozone dissociation could combine with the photogenerated electrons to form superoxide radicals which are also conductive to the toluene degradation.

FACETS软件用于评价临床护理操作考核成绩的可行性研究

目的探讨将多面Rasch测量分析软件FACETS应用于临床护理考核成绩分析中的可行性。方法以成人心肺复苏操作考核为标准,以6名护士长为考核人员,采用多面Rasch测量分析软件FACETS对护生30人的考核成绩进行分析,以评定考核人员评分的宽严程度和自身一致性。结果考核人员评分宽严程度Logit值-1.53～2.01,自身一致性Infit值0.82～1.32,Ontfit值0.44～1.28。宽严度与自身一致性存在一定的差异。结论多面Rasch测量分析软件FACETS可作为临床护理考核成绩分析的有效工具。

MID-FACETS OF A SIMPLEX

The mid-facet of a simplex in n-dimensional Euclidean space which was introduced quite recently is an important geometric element. An analytic expression for the mid-facet area of a simplex is firstly given. In order to obtain the expression,the exterior differential method was presented. Furthermore, the properties of the mid-facets of a simplex analogous to median lines of a triangle (such as for all mid-facets of a simplex,there exists another simplex such that its edge-lengths equal to these mid-facets area respectively, and all of the mid-facets of a simplex have a common point) were proved. Finally, by applying the analytic expression, a number of inequalities which combine edge-lengths, circumradius, median line, bisection area and facet area with the mid-facet area for a simplex were established.

多面Rasch模型分析软件Facets在英语测试中的应用研究

文章描述了多面Rasch模型的原理,并就其分析软件Facets在国内外英语测试中的研究现状做了评述;然后,通过实例重点讲述了如何运用Facets软件进行实验设计、编写分析语句、运行程序,以及如何从考生面、评分者面、评分标准面等对其产生的图表进行了解读。

基于FACET滤波加权局部对比度的红外小目标检测

针对低空复杂背景下红外图像中目标与背景对比度低、边缘高亮的问题,提出一种基于FACET滤波加权局部对比度的红外小目标检测算法。首先,通过FACET滤波运算获取目标候选像素;然后,利用目标区域和背景区域灰度差异的比率计算局部对比度,同时基于目标和背景的异质性设计了一种加权函数,用来增强目标显著性和抑制背景;最后,通过自适应阈值分割提取真实的目标。在5组真实红外小目标图像数据集上与不同的算法进行性能比较分析,实验结果表明,提出的算法在不同低空复杂场景中具有较好的检测性能。