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Meaningful comparison of photocatalytic properties of {001} and {101} faceted anatase tio2 nanocrystals

Science Bulletin 2016年第13期61卷 1003-1012页

作者： Yang Lu Yipeng Zang Haimin Zhang Yunxia Zhang Guozhong Wang Huijun Zhao Key Laboratory of Materials Physics Centre for Environmentaland Energy Nanomaterials Anhui Key Laboratory of Nanomaterials and Nanotechnology Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China University of Science and Technology of China Hefei 230026China Centre for Clean Environment and Energy Griffith UniversityGold Coast Campus Gold Coast QLD 4222 Australia

The facet-dependent photocatalytic performance of tio_2 nanocrystals has been extensively investigated due to their promising applications in renewable energy and environmental fields. However, the intrinsic distinction in the photocatalytic oxidation activities between the {001}and {101} facets of anatase tio_2 nanocrystals is still unclear and under debate. In this work, a simple photoelectrochemical method was employed to meaningfully quantify the intrinsic photocatalytic activities of {001} and{101} faceted tio_2 nanocrystal photoanodes. The effective surface areas of photoanodes with different facets were measured based on the monolayer adsorption of phthalic acid on tio_2 photoanode surface by an ex situ photoelectrochemical method, which were used to normalize the photocurrents obtained from different faceted photoanodes for meaningful comparison of their photocatalytic activities. The results demonstrated that the {001} facets of anatase tio_2 nanocrystals exhibited much better photocatalytic activity than that of {101} facets of anatase tio_2 nanocrystals toward photocatalytic oxidation of water and organic compounds with different functional groups(e.g.,–OH, –CHO, –COOH). Furthermore, the instantaneous kinetic constants of photocatalytic oxidation of pre-adsorbates on {001} faceted anatase tio_2 photoanode are obviously greater than those obtained at {101} faceted anatase tio_2 photoanode, further verifying the higher photocatalytic activity of {001} facets of anatase tio_*** work provided a facile photoelectrochemical method to quantitatively determine the photocatalytic oxidation activity of specific exposed crystal facets of a photocatalyst, which would be helpful to uncover and meaningfully compare the intrinsic photocatalytic activities of different exposed crystal facets of a photocatalyst.

关键词： anatase tio2 Crystal facet Photocatalysis Structure-activity relationships

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Impact of Oxygen Vacancy on Band Structure Engineering of n-p Codoped anatase tio2

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Chinese Journal of Chemical Physics 2015年第2期28卷 155-160,I0001页

作者：孟强强王加军黄静李群祥中国科学技术大学合肥微尺度物质科学国家实验室合肥230026 天津师范大学化学院天津300387 安徽建筑大学材料与化工学院合肥230601

Doping with various impurities is an effective approach to improve the photoelectrochemical properties of tio2. Here, we explore the effect of oxygen vacancy on geometric and elec- tronic properties of compensated （i.e. V-N and Cr-C） and non-compensated （i.e. V-C and Cr-N） codoped anatase tio2 by performing extensive density functional theory calculations. Theoretical results show that oxygen vacancy prefers to the neighboring site of metal dopant （i.e. V or Cr atom）. After introduction of oxygen vacancy, the unoccupied impurity bands located within band gap of these codoped tio2 will be filled with electrons, and the posi- tion of conduction band offset does not change obviously, which result in the reduction of photoinduced carrier recombination and the good performance for hydrogen production via water splitting. Moreover, we find that oxygen vacancy is easily introduced in V-N codoped tio2 under O-poor condition. These theoretical insights are helpful for designing codoped tio2 with high photoelectrochemical performance.

关键词： Oxygen vacancy Band structure engineering n-p codoped anatase tio2

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Quasiparticle Band Structures of Defects in anatase tio2 Bulk

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Chinese Journal of Chemical Physics 2017年第6期30卷 771-775,I0003页

作者：陈廷威郝亚南马玉臣山东大学化学与化工学院济南250100

Quasiparticle band structures of the defective anatase tio2 bulk with O vacancy, Ti interstitial and H interstitial are investigated by the GW method within many-body Green＇s function theory. The computed direct band gap of the perfect anatase bulk is 4.3 eV, far larger than the experimental optical absorption edge （3.2 eV）. We found that this can be ascribed to the inherent defects in anatase which drag the conduction band （CB） edge down. The occupied band-gap states induced by these defects locate close to the CB edge, exclud- ing the possible contribution of these bulk defects to the deep band-gap state below CB as observed in experiments.

关键词： anatase tio2 Defect GW method Band structure Optical absorption edge

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First-Principles Study of La Doping Effects on the Electronic Structures and Photocatalytic Properties of anatase tio2

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Chinese Journal of Chemical Physics 2015年第6期28卷 -页

作者： Ping Huang Bo Shang Ling-jie Li Jing-lei Lei School of Chemistry and Chemical Engineering Chongqing University Chongqing 400044 China

The effects of doping concentration, position and oxygen vacancy defect on the stability, electronic and optical properties of La-doped anatase tio2 have been investigated based on DFT+U method. The calculations indicated that the doping concentration and sites of La affected the stability and band gap of La-doped tio2 significantly due to the lattice distortion, which obey the ionic Pauling's rules and crystal field theories; moreover, the simulated adsorption spectrum shows an obviously increase in the photocatalysis properties, which are in good agreement with recently experimental measurements. The oxygen vacancy defect will enhance the structural stability and the adsorption of visible light in La-doped tio2 system, which is important in photocatalytic application.

关键词： Density functional theory La doping anatase tio2 Oxygen vacancy

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The adsorption and activation of formic acid on different anatase tio2 surfaces

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Journal of Energy Chemistry 2017年第4期26卷 738-742页

作者： Huaqing Dong Zhenzhan Zhuang Yongbing Gu Jianrong Gao College of Chemical Engineering Zhejiang University of TechnologyHangzhou 310014ZhejiangChina College of Science Zhejiang University of TechnologyHangzhou 310014ZhejiangChina Department of Chemistry and Chemical Engineering Lishui UniversityLishui 323000ZhejiangChina

Formic acid photodegradation is one of the most important reactions in organic pollution control, and helps to improve the hydrogen generation efficiency in titanium dioxide catalyzed water photodecomposition. Based on density functional theory and Reax FF molecular dynamics, the adsorption, diffusion and activation of formic acid on the different anatase tio（101）,（001）,（010） surfaces are *** result shows that the adsorption of COOH on anatase tiosurface shrinks the energy gap between the dehydrogenation intermediate COOH and HCOO. On the anatase tio（101） surface, the formic acid breaks the O–H bond at the first step with activation energy 0.24 eV, and the consequent break of α-H become much easier with activation energy 0.77 eV. The dissociation of α-H is the determination step of the HCOOH decomposition.

关键词： Formic acid anatase tio2 Density functional theory Photodegradation

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Surface energy-driven solution epitaxial growth of anatase tio_(2) homostructures for overall water splitting

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Journal of Materials Science & Technology 2020年第11期42卷 139-144页

作者： Shi Li Luoyuan Ruan Shanpeng Wang Zhiyu Wang Zhaohui Ren Gaorong Han State Key Laboratory of Silicon Materials School of Materials Science and EngineeringCyrus Tang Center for Sensor Materials and ApplicationZhejiang UniversityHangzhou310027China State Key Laboratory of Crystal Materials Shandong UniversityJinan250100China

Titanium dioxide(tio_(2))has been extensively investigated as a photocatalyst for water splitting to produce ***,an overall water splitting by using anatase tio_(2) is extremely difficult due to the short lifetime of *** this work,we propose that a surface energy decrease from{001}to{101}of anatase tio_(2) is able to drive an epitaxial growth.A novel anatase tio_(2) homostructure has been successfully synthesized via a facile hydrothermal route,where{101}semi-pyramid nanoparticles epitaxially grew on the both sides of the{001}*** epitaxial relationship between the nanoparticles and the nanosheets has been characterized to be{001}//{001}of anatase tio_(2).For the first time,it is interesting to find that the homostructure with 12 wt%of{101}semi-pyramid can significantly improve the H2 evolution rate by nearly 5 times compared to the pure nanosheets under the ultraviolet *** importantly,such homostructure enables 10.78μmol g-1h-1 of O_(2) production whereas the pure nanosheets cannot evolve detectable O_(2) ***,the time-resolved photoluminescence analysis indicates that the mean lifetime of the holes is increased from 2.20 ns of the nanosheets to 3.59 ns of the homostructure,accounting for the observed overall water *** findings suggest that constructing a homostructure by a surface energy strategy could be promising towards overall water splitting,which may be applicable to other photocatalytic materials.

关键词： {001} {101} Homostructure anatase tio2 Overall water splitting

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Preparation and Photocatalytic Behaviors of Nanoporous Polyoxotungstate-anatase tio_2 Composites

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Journal of Rare Earths 2007年第1期25卷 68-73页

作者：李莉李英杰马禹郭伊荇 Faculty of Chemistry Northeast Normal UniversityChangchun 130024 China Faculty of Chemistry and Chemical Engineering Qiqihar UniversityQiqihar 161006 China

Nanoporous anatase tio2 crystalline particles coupled with Keggin or Wells-Dawson unit, H3PW12O40/tio2 or H6P2W18O62/tio2, were prepared at a low temperature （200℃ ） using sol-gel method combined with hydrothermal treatment at programmed temperature. The as-prepared composites have uniform anatase phase, and they exhibit both micrand mesoporosities with pore sizes of 0.6 and 4.0 nm, respectively, and their average size is lower than 10 nm. Photocatalytic tests show the composites exhibit relatively higher photocatalytic activities to decompose the organocholorine pesticide hexachlorobenzene（HCB） than anatase tio2, the starting polyoxotungstates, and EuEOa/tio2 prepared by using sol-gel method, and this was attributed to （ 1 ） the synergistic effect of photoactive anatase tio2 with the polyoxotungstate, and （2） the fascinating physical and chemical properties of the porous materials.

关键词： polyoxotungstate anatase tio2 photocatalysis sol-gel hydrothermal treatment

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Fluoride-assisted synthesis of anatase tio_2 nanocrystals with tunable shape and band gap via a solvothermal approach

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Chinese Chemical Letters 2016年第12期27卷 1801-1804页

作者： Zhe-Ming Liu Lan Peng Ai-Wei Tang Department of Chemistry School of Science Beijing Jiaotong University

A simple solvothermal approach employing oleic acid has been developed to prepare anatase tio2 nanocrystals with different shapes, which were tuned from nanorods to nano-ellipsoids by increasing the amount of NaF from 0 to 0.5 retool, and the optical band gap decreased from 3.47 eV to 3.29 eV accordingly. However, when the fluoride was changed to NH4F, the resultant tio2 nanocrystals possessed an anatase phase but were made up of smaller-sized nanocrystals and nanorods, and the band gap was increased to 3.53 eV. The X-ray photoelectron spectroscopy （XPS） results illustrated an increase of fluorine content with an increasing amount of NaF could account for the variation of the shape and optical band gap of tio2 nanocrystals. Moreover, the absence of fluorine content brought about less change of shape and increase of optical band gap of the product synthesized in the presence of NH4F. This result may offer another way to alter the shape and band gap of metal oxide nanocrystals with the assistance of fluoride.

关键词： anatase tio2 Fluoride Synthesis Optical band gap Solvothermal approach

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First principle study of the electronic structure of hafnium-doped anatase tio_2

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Journal of Semiconductors 2012年第1期33卷 25-28页

作者： Li Lezhong Yang weiqing Ding Yingchun Zhu Xinghua Department of Optics and Electronics Chengdu University of Information Technology Chengdu 610225China

Crystal structures and electronic structures of hafnium doping anatase tio2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on the density functional theory within the generalized gradient approximation. The calculated results show that the lattice parameters a and c of Hf-doped anatase tio2 are larger than those of intrinsic tio2 under the same calculated condition. The calculated band structure and density of states show that the conduction band width of Hf-doped tio2 is broadened which results in the band gap of Hf-doped being smaller than the band gap of tio2.

关键词： Hf-doped anatase tio2 first principle crystal structure electronic structure

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Effects of crystallinity, {001}/{101} ratio, and Au decoration on the photocatalytic activity of anatase tio_2 crystals

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Chinese Journal of Catalysis 2019年第3期40卷 403-412页

作者： Jiangyan Wang Baoshun Liu Kazuya Nakata State Key Laboratory of Silicate Materials for Architectures Wuhan University of Technology Wuhan 430070 Hubei China Research Institute for Science and Technology Photocatalysis International Research Center Tokyo University of Science 2641 Yamazaki Noda Chiba 278-8510 Japan Science and Technology Tokyo University of Science 2641 Yamazaki Noda Chiba 278-8510 Japan

anatase tio2 nanocrystals and sub-microcrystals with truncated octahedral bipyramidal morphologies were prepared by direct calcination of tioF2 precursors. The as-prepared tio2 samples were thoroughly characterized by X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and UV-visible diffuse spectroscopy. It was found that the crystallinity, grain size, and {001}/{101} ratio of the samples can be increased by raising the calcination temperature from 500 to 800℃. The higher crystallinity and {001}/{101} facet ratio resulted in an increase in both aqueous and gas-phase photocatalytic activities, by inhibiting the recombination and separation of electrons and holes. After selecting two tio2 samples with high crystallinity and {001}/{101} ratio, Au nanoparticles were decorated on their surfaces, and the photocatalytic activity of the resulting samples under visible light illumination was studied. It was found that the visible light-induced photocatalytic activity increased by 2.6 and 4.8 times, respectively, upon Au decoration of the samples prepared by calcination of tioF2 at 700 and 800℃.

关键词： High crystallinity anatase tio2 High energy facets Au decoration Photocatalysis

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