• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    球形、花形和線狀釩酸鉍的可控合成及光催化性能

    2013-09-17 06:59:10于麗麗閆麗娜關(guān)慶豐閆永勝
    物理化學(xué)學(xué)報 2013年8期
    關(guān)鍵詞:花形化工學(xué)院物理化學(xué)

    林 雪 于麗麗 閆麗娜 關(guān)慶豐 閆永勝 趙 晗

    (1吉林師范大學(xué)化學(xué)學(xué)院,環(huán)境友好材料制備與應(yīng)用教育部重點(diǎn)實(shí)驗(yàn)室,吉林四平136000;2江蘇大學(xué)材料科學(xué)與工程學(xué)院,江蘇鎮(zhèn)江212013;3江蘇大學(xué)化學(xué)化工學(xué)院,江蘇鎮(zhèn)江212013)

    1 Introduction

    From the viewpoint of the environment issues,the direct use of solar energy such as clean and renewable energy through visible-light-driven photocatalysis for environmental pollution control has attracted great interest.1-8In recent years,there are many papers focused on the preparation of bismuth compounds which can degrade organic pollutants under visible light irradiation.9-13The semiconducting oxides containing bismuth with narrow band gap,such as BiVO4,9,10Bi2WO6,11,12and Bi2MoO6,13have received intensive interest because of their visible-light-driven photocatalytic activities.Among bismuth-containing photocatalysts,BiVO4has received more attention for its high photocatalytic ability for environmental applications and/or water splitting.

    Recently,much attention has been paid to the synthesis of BiVO4nanostructures with different sizes and shapes due to their good visible light responsive photocatalytic activites compared with its bulk counterpart.14-17Traditional solid-state reaction usually produces large irregular BiVO4crystals due to its fast crystal growth feature.Moreover,crystallographic facets with high surface energies diminish during the crystal growth process for minimization of surface energy.A variety of solution-based methods including aqueous,hydrothermal,and solvothermal process,have been developed to fabricate BiVO4nanostructures,such as nanoellipsoids,18-20nanowires/nanofibers,21,22nanosheets/nanoplates,23,24and hyperbranched crystals.25However,the ability to control the morphologies of BiVO4nanostructures,such as sizes and well-defined shapes(or crystallographic facets exposed on the surface),remains a great challenge,that can provide a great opportunity to improve their properties.

    Herein,we report a simple hydrothermal method without using any surfactant or template for the successful synthesis of BiVO4crystals with well controlled shapes.The photocatalytic activities of the BiVO4samples with different morphologies have been discussed.The aim of the present paper is to study the influence of structure and morphology upon the optical properties and photocatalytic properties of BiVO4photocatalysts.

    2 Experimental

    2.1 Preparation of BiVO4photocatalysts

    All reagents used in our experiment are of analytical purity(purchased from Shanghai Chemical Industrial Company)and used without further purification.In a typical synthesis of BiVO4,0.970 g of Bi(NO3)3·5H2O were dissolved into 35 mL of distilled water.Then an aqueous solution of NH4VO3(0.234 g of NH4VO3,5 mL of distilled water)was added to the above mixture under magnetic stirring to form an orange emulsion.The pH value of the reaction mixture was adjusted from 1 to 3 with ammonia solution(25%-28%(w))under vigorous stirring.After stirring for 0.5 h at room temperature,the reaction mixture was transferred into a stainless steel autoclave,and kept at 180°C for 12 h.The resulting yellow product was collected,washed with ethanol and distilled water several times,and then dried at 100°C for 10 h.The sample prepared for comparison is N-doped TiO2(N-TiO2),which was synthesized according to Hou et al.26

    2.2 Characterization of BiVO4photocatalyst

    The crystal structures of the samples were characterized by X-ray diffraction(XRD)on a Rigaku(Japan)D/max 2500 X-ray diffractometer(Cu Kαradiation,λ=0.15418 nm).Transmission electron microscopy(TEM)was conducted using a JEM-2100F(Japan JEOL)instrument.The Fourier transform infrared(FTIR)spectra were measured by FTIR spectrometer(America Perkin Elmer,Spectrum One).Raman spectra of BiVO4samples were obtained by a micro laser Raman spectrometer(LabRam inva).Raman spectra were excited with the 514 nm line of an Ar+laser at an incident power of 20 mW.The surface areas of samples were measured by TriStar 3000-BET/BJH Surface Area.The optical property was obtained by the photoluminescence(PL)measurement using HR800 LabRam Infinity Spectro photometer excited by a continuous He-Cd laser with a wavelength of 325 nm at a power of 50 mW.The diffuse reflectance spectra(DRS)were measured by a UV-Vis spectrometer(UV-2550,Shimadzu).BaSO4was used as the reflectance standard material.

    2.3 Photocatalytic activities

    The photocatalytic activities of BiVO4samples were evaluated using RhB dye as a model compound.In experiments,the RhB dye solution(0.005 mmol·L-1,100 mL)containing 0.02 g of BiVO4photocatalyst was mixed in a pyrex reaction glass.A 500 W Xe lamp(λ>420 nm)was used to provide visible light irradiation.A glass sheet was inserted between the lamp and the sample to filter out UV light(λ<420 nm).Prior to visible light illumination,the suspension was strongly magnetically stirred for 30 min in the dark for adsorption/desorption equilibrium.Then the solution was exposed to visible light irradiation under magnetic stirring.At given time intervals,about 4 mL of the suspension was periodically withdrawn and analyzed after centrifugation.The RhB concentration was analyzed by a UV-2550 spectrometer to record intensity of the maximum band at 552 nm in the UV-Vis absorption spectra.

    3 Results and discussion

    Fig.1 shows the XRD patterns of the as-prepared BiVO4samples.All diffraction peaks can be assigned to the monoclinic structure of BiVO4(JCPDS No.14-0688).This observation is further confirmed by the splitting of the peaks at 2θ=18.5°,35°,and 46°,which is characteristic of the monoclinic structure of BiVO4.No peaks of impurities were detected from these patterns.The strong and sharp peaks indicate high crystallinity of the samples.However,the intensities of the peaks of BiVO4samples are different which proves that there are some differences among the samples prepared with different pH values.BiVO4sample prepared at pH value of 3 has the strongest peak intensity,which means that the crystallinity of the sample was developing with the increase of pH value.

    TEM was used to observe the morphologies and structure details of BiVO4products.Fig.2(a-c)shows the TEM images of the as-prepared BiVO4samples obtained at different conditions.Fig.2(a)gives a typical example of microspheres with average sizes of 200 nm,approximately.It can be observed that there are BiVO4nanorods with average width of about 100 nm(as shown in Fig.2(b)).These nanorods intersect with each other forming microflowers.It can be seen in Fig.2(c)that there are BiVO4microwires with width of approximate 200 nm and lengths up to several micrometres.

    Fig.1 XRD patterns of the as-prepared BiVO4samples obtained at different pH values

    These results indicate that pH value seems to play an important role in determining final morphologies of BiVO4.Namely,morphology of BiVO4powders can be controlled through varying the pH value.Although the crystal growth habit is mainly determined by the intrinsic structure,it is also affected by the external conditions such as pH value of the solution,saturation,temperature,etc.27As we all know,the pH value in the precursor solution has been found to be very important for the microstructure.In this work,the condition of the pH value as a factor is considered to play a key part in the formation of BiVO4crystals with different morphologies.At low pH value(pH=1),BiVO4nuclei produced in solution can aggregate to form small mirospheres.With the pH value increase continuing(pH=3),a large amount of BiVO4nuclei produced in the solution lead to form the very high supersaturation solution,which favors the formation of threadlike structure.When pH value is relatively lower(pH=2),only BiVO4nanorods are obtained because of lower driving force,which come from the lower chemical potential.These nanorods intersect with each other forming microflowers.

    Diffuse reflectance spectroscopy is a useful tool for characterizing the electron states in optical materials.The UV-Vis diffuse reflectance spectra(UV-Vis DRS)of the as-prepared BiVO4samples are shown in Fig.3.As a comparison,the spectra of P25 TiO2and N-TiO2were also measured.The BiVO4products exhibit strong absorption in the visible range in addition to the UV range.The steep absorption edge in the visible range indicates that the absorption of visible light is not due to the transition from impurity levels but to the band gap transition.28The band gap energies(Eg)of BiVO4samples are calculated to be about 2.33,2.24,and 2.19 eV,based on the formula:Eg=1240/λg,which show marked red shift in the absorbance compared to P25 and N-TiO2.It indicates that BiVO4photocatalysts have a suitable band gap for photocatalytic decomposition of organic contaminants under visible light irradiation.In this system,slight red shift of the absorption band edge of BiVO4samples(from 2.19 to 2.33 eV)can be observed with the pH value increasing from 1 to 3.It is well known that the band gap energy of semiconductor nanoparticles increases with the decrease of grain size.Herein,BiVO4with one-dimensional(1D)microstructure(pH 3)had a red shift in the band-gap tran-sition compared with spherical and flowerlike BiVO4(pH 1,pH 2),attributed to the smaller grain sizes of spherical and flowerlike BiVO4than that of the 1D microwires.

    Fig.2 TEM images of the as-prepared BiVO4samples obtained at different pH values

    Fig.3 UV-Vis DRS of samples

    Notably,it has been established that the photoluminescence(PL)spectra originate from the direct recombination of photoexcited electrons and holes.29In order to further study the efficient separation of photogenerated carriers in BiVO4,the corresponding photoluminescence spectra were obtained to disclose the migration,transfer,and recombination processes of photogenerated electron-hole pairs.Fig.4 shows the PL spectra of Bi-VO4samples measured at room temperature at an excitation wavelength of 325 nm.As shown,a yellow emission near 591 nm was clearly observed in all the three kinds of BiVO4samples,but for a slight blue shift in BiVO4crystals with the particle size decreased,which is in agreement with the previous report.29The fluorescence intensity of BiVO4microspheres was significantly weaker than those of threadlike and flowerlike products,which shows the recombination restraint of the electron-hole(e-/h+)pairs.

    Fig.4 PLspectra of the as-prepared BiVO4samples

    During the course of the photocatalysis,the BiVO4catalyst in the RhB resolution destroys not only the RhB conjugated system,but also its molecular structure.When the RhB adsorbed on the surface of BiVO4is excited,it injects an electron(e-)into the conduction band(CB)of BiVO4.The electron can reduce molecular oxygen to superoxide anion and later transform to organic peroxides or hydrogen peroxide.Another reactive intermediate which is responsible for the degradation is hydroxyl radical(·OH).The hydroxyl radical is an extremely strong,non-selective oxidant which leads to the partial or complete mineralization of several organic chemicals.After a series of complicated oxidation reaction,the RhB is decomposed to smaller organics and minerals,like CO2,H2O,and so on.30

    Because the direct oxidation of RhB by positive holes(h+)adsorbed on the surface of BiVO4is considered to be the main oxidation pathway,the specific surface area plays an important role in the speed of photocatalytic process.31The BET results show that the specific surface area of BiVO4microspheres is 22.16 m2·g-1,the flowerlike BiVO4nanostructure is 10.30 m2·g-1,and BiVO4microwires is 8.08 m2·g-1(as shown in Table 1).It is clearly revealed that the samples with small size(pH 1)can more efficiently adsorb the RhB due to their higher BET surface area than other samples with larger sizes.Higher specific surface area means that the total active surface area increases at the same catalyst loading,hence availability of more active sites on catalyst surface.32,33In order to prove the effect of the specific surface area,the experiments were performed by comparing in microspheres,microflowers and microwires with 0.02 g catalyst loading for RhB solutions of 0.005 mmol·L-1.The photodegradation for the three kinds of BiVO4samples has been displayed in Fig.5.For comparison,the photodegradation of RhB by P25,N-TiO2,and that without any catalyst were also carried out.From the catalytic studies,BiVO4samples are found to be more photoactive towards RhB solution than P25,and N-TiO2.The photolysis test demonstrates that the degradation rate of RhB by microspheres increases to 100%after 180 min irradiation,much higher than that of microflowers and microwires.The increasing of BET surface areas and the decreaseof crystalline grains were both beneficial to the enhancement of the photocatalytic activity of BiVO4.32In addition,the different photodegradation rates of RhB by different BiVO4samples indicated that the photocatalytic performances of these BiVO4samples are greatly different and strongly dependent on shape,crystal size,and structure.

    Table 1 Band gap energy(Eg),BET specific surface area(SBET),and absorption percentages of photocatalysts in the dark

    Fig.5 Photodegradation efficiencies of RhB as a function of irradiation time for different photocatalysts

    The stability tests were conducted by using recycling reactions four times for the photodegradation of RhB over BiVO4photocatalyst under visible light irradiation(as displayed in Fig.6).No significant decrease in catalytic activity was detected in the recycling reactions.It demonstrates that the BiVO4sample is a stable photocatalyst for degradation of RhB under visible light irradiation.

    The photocatalytic property of BiVO4is also related to the distortion of the M-O polyhedron in crystal structure.Raman spectroscopy is effective to probe the local structure of materials because the Raman spectrum reflects the bonding states in the coordination polyhedron of a material.Raman spectra of the as-prepared BiVO4samples are shown in Fig.7.Raman bands at 212,328,369,and 827 cm-1were observed in the spectra of the samples prepared by the hydrothermal method.These Raman bands represented the typical vibration bands of monoclinic scheelite BiVO4and could be assigned to the asymmetric and symmetric deformation modes of VO3-4and the symmetric stretching mode of the V-O bond,respectively.34,35However,an obvious change of the Raman band intensity occurred in this range varying with the increasing of pH values in reaction system.The dependence of the relative intensities of the asymmetric and symmetric deformation vibrations(212 and 328 cm-1)of the VO3-4on the synthesis conditions is observed,demonstrating that different space symmetries are formed and the variation or rearrangement of the crystal structure exists under the influence of reaction conditions(pH value).A similar Raman-band shift of the Mo-O stretching vibration was also observed in the Raman spectrum of Bi2MoO6.32

    Fig.6 Stability evaluation for the as-prepared BiVO4sample

    Fig.7 Raman spectra of the as-prepared BiVO4samples obtained at different pH values

    FTIR spectra of BiVO4samples are shown in Fig.8.The FTIR spectra of BiVO4samples are similar with each other except for that the absorption bond of BiVO4microspheres at 3446 cm-1displays a slight blue shift compared to BiVO4microflowers and BiVO4microwires.The obvious absorptions at 1651 and 3446 cm-1can be ascribed to bending and stretching vibrations of the adsorbed H2O molecules,respectively.36,37The medium peak at 1419 cm-1indicates adsorbed trace NO-3.38,39The two strong absorption bands at 821 cm-1and 746 cm-1belong to the stretching vibration and deformation bending vibration of VO3-

    4,respectively.39Minor down shift of wavenumber at 746 cm-1is observed,indicating that the variation of structure for VO3-4may be occurred with the increasing of pH values in this system.Several differences in half-widths and intensities of the diffraction peaks were observed in the XRD patterns of BiVO4synthesized hydrothermally at various pH values(Fig.1),indicating that slight changes in the structure,even though all the powders exhibited the monoclinic structure.Based on the above results and analysis,it can be concluded that the changing of pH value in reaction system may influence the crystal structure and corresponding photocatalytic performance.

    The above experiments have shown the excellent photocatalytic performance of the as-prepared BiVO4samples on the degradation of the widely used dye RhB.It follows that the BiVO4photocatalyst may have highly potential applications in the conservation of the environment.Not only limited to the experimental results,the photodegraded mechanism of RhB in the visible light/BiVO4system was necessary to investigate and guide the further improvement of its photocatalytic performance.

    Fig.8 FTIR spectra of the as-prepared BiVO4samples obtained at different pH values

    For BiVO4system,photo-oxidations occurring in aqueous media,the mechanism may involve direct reaction of the organic chemical(dye)with surface h+vb(vb:valence band),indirect reaction with·OH radicals or a dual mechanism involving both surfaceand·OH radicals.40,41The pathway of photocatalytic degradation can be described through the following equations:

    4 Conclusions

    BiVO4photocatalysts with different morphologies have been synthesized through a facile,pH-controlled,surfactant-free hydrothermal route.XRD results confirmed that the composition of the as-fabricated samples is of monoclinic structure.The energy band gaps of BiVO4samples are found to be about 2.19-2.33 eV.Extension of the light absorption from the ultraviolet region to the visible-light region was confirmed by UVVis DRS.Due to the structure property relationships,BiVO4photocatalysts show enhanced visible photocatalytic activities over those of P25 and N-TiO2in the decomposition of RhB in water.Our work suggests that the photocatalytic performance of BiVO4is greatly dependent on the local structure and the morphology.Thehydrothermaltechniquepresented here seems an economical and easy way for the morphology and local structure control of such material.

    (1)Hu,Y.F.;Li,Y.X.;Peng,S.Q.;Lü,G.X.;Li,S.B.Acta Phys.-Chim.Sin.2008,24(11),2071.[胡元方,李越湘,彭紹琴,呂功煊,李樹本.物理化學(xué)學(xué)報,2008,24(11),2071.]doi:10.3866/PKU.WHXB20081123

    (2)Mao,Y.B.;Wong,S.S.J.Am.Chem.Soc.2006,128,8217.doi:10.1021/ja0607483

    (3)Li,B.X.;Wang,Y.F.;Liu,T.X.Acta Phys.-Chim.Sin.2011,27(12),2946.[李本俠,王艷芬,劉同宣.物理化學(xué)學(xué)報,2011,27(12),2946.]doi:10.3866/PKU.WHXB20112946

    (4) Zhang,L.S.;Wang,H.L.;Chen,Z.G.;Wong,P.K.;Liu,J.S.Appl.Catal.B:Environ.2011,106,1.

    (5) Grasset,F.;Starukh,G.;Spanhel,L.;Ababou-Girard,S.;Su,D.S.;Klein,A.Adv.Mater.2005,17,294.

    (6) Grasset,F.;Spanhel,L.;Ababou-Girard,S.Superlattice Microst.2005,38,300.doi:10.1016/j.spmi.2005.08.023

    (7)Yao,W.F.;Wang,H.;Xu,X.H.;Zhou,J.T.;Yang,X.N.;Zhang,Y.;Shang,S.X.Appl.Catal.A:Gen.2004,259,29.doi:10.1016/j.apcata.2003.09.004

    (8)Yao,W.F.;Xu,X.H.;Wang,H.;Zhou,J.T.;Yang,X.N.;Zhang,Y.;Shang,S.X.;Huang,B.B.Appl.Catal.B:Environ.2004,52,109.doi:10.1016/j.apcatb.2004.04.002

    (9) Liu,Y.Y.;Huang,B.B.;Dai,Y.;Zhang,X.Y.;Qin,X.Y.;Jiang,M.H.;Whangbo,M.H.Catal.Commun.2009,11,210.doi:10.1016/j.catcom.2009.10.010

    (10)Zhang,Z.J.;Wang,W.Z.;Shang,M.;Yin,W.Z.Catal.Commun.2010,11,982.doi:10.1016/j.catcom.2010.04.013

    (11)Zhang,L.W.;Wang,Y.J.;Cheng,H.Y.;Yao,W.Q.;Zhu,Y.F.Adv.Mater.2009,21,1286.doi:10.1002/adma.v21:12

    (12) Zhuo,Y.Q.;Huang,J.F.;Cao,L.Y.;Ouyang,H.B.;Wu,J.P.Mater.Lett.2013,90,107.doi:10.1016/j.matlet.2012.09.009

    (13)Tian,G.H.;Chen,Y.J.;Meng,X.Y.;Zhou,J.;Zhou,W.;Pan,K.;Tian,C.G.;Ren,Z.Y.;Fu,H.G.ChemPlusChem 2013,78,117.doi:10.1002/cplu.201200198

    (14) Kudo,A.;Ueda,K.;Kato,H.;Mikami,I.Catal.Lett.1998,53,229.doi:10.1023/A:1019034728816

    (15)Zhou,L.;Wang,W.;Liu,S.;Zhang,L.;Xu,H.;Zhu,W.J.Mol.Catal.A:Chem.2006,252,120.doi:10.1016/j.molcata.2006.01.052

    (16) Tokunaga,S.;Kato,H.;Kudo,A.Chem.Mater.2001,13,4624.doi:10.1021/cm0103390

    (17) Liu,J.B.;Wang,H.;Wang,S.;Yan,H.Mater.Sci.Eng.B 2003,104,36.doi:10.1016/S0921-5107(03)00264-2

    (18)Sun,Y.;Wu,C.;Long,R.;Cui,Y.;Zhang,S.;Xie,Y.Chem.Cummun.2009,4542.

    (19) Sun,Y.;Xie,Y.;Wu,C.;Long,R.Cryst.Growth Des.2010,10,602.doi:10.1021/cg900988j

    (20) Shang,M.;Wang,W.;Sun,S.;Ren,J.;Zhou,L.;Zhang,L.J.Phys.Chem.C 2009,113,20228.doi:10.1021/jp9067729

    (21) Su,J.;Guo,L.;Yoriya,S.;Grimes,C.A.Cryst.Growth Des.2010,10,856.doi:10.1021/cg9012125

    (22) Yu,J.;Kudo,A.Chem.Lett.2005,34,850.doi:10.1246/cl.2005.850

    (23) Xi,G.;Ye,J.Chem.Commun.2010,46,1893.doi:10.1039/b923435g

    (24) Zhang,L.;Chen,D.;Jiao,X.J.Phys.Chem.B 2006,110,2668.doi:10.1021/jp056367d

    (25) Zhao,Y.;Xie,Y.;Zhu,X.;Yan,S.;Wang,S.Chem.Eur.J.2008,14,1601.

    (26)Hou,Y.D.;Wang,X.C.;Wu,L.;Chen,X.F.;Ding,Z.X.;Wang,X.X.;Fu,X.Z.Chemosphere 2008,72,414.doi:10.1016/j.chemosphere.2008.02.035

    (27)Yang,J.H.;Zheng,J.H.;Zhai,H.J.;Yang,L.L.;Lang,J.H.;Gao,M.J.Alloy.Compd.2009,481,628.doi:10.1016/j.jallcom.2009.03.108

    (28)Kudo,A.;Tsuji,I.;Kato,H.Chem.Commun.2002,48,1958.

    (29)Xu,D.;Gao,A.M.;Deng,W.L.Acta Phys.-Chim.Sin.2008,24(7),1219.[許 迪,高愛梅,鄧文禮.物理化學(xué)學(xué)報,2008,24(7),1219.]doi:10.3866/PKU.WHXB20080717

    (30) Wang,D.G.;Li,R.G.;Zhu,J.;Shi,J.Y.;Han,J.F.;Zong,X.;Li,C.J.Phys.Chem.C 2012,116,5082.doi:10.1021/jp210584b

    (31) Cao,S.W.;Yin,Z.;Barber,J.;Boey,F.Y.C.;Loo,S.C.J.;Xue,C.ACS Appl.Mater.Interfaces 2012,4,418.doi:10.1021/am201481b

    (32)Zhang,L.W.;Xu,T.G.;Zhao,X.;Zhu,Y.F.Appl.Catal.B:Environ.2010,98,138.doi:10.1016/j.apcatb.2010.05.022

    (33)Wang,X.;Chen,G.;Zhou,C.;Yu,Y.G.;Wang,G.Eur.J.Inorg.Chem.2012,1742.

    (34) Li,G.S.;Zhang,D.Q.;Yu,J.C.Chem.Mater.2008,20,3983.doi:10.1021/cm800236z

    (35) Wetchakun,N.;Chaiwichain,S.;Inceesungvorn,B.;Pingmuang,K.;Phanichphant,S.;Minett,A.I.;Chen,J.ACS Appl.Mater.Interfaces 2012,4,3718.doi:10.1021/am300812n

    (36) Ke,D.N.;Peng,T.Y.;Ma,L.;Cai,P.;Dai,K.Inorg.Chem.2009,48,4685.doi:10.1021/ic900064m

    (37) García,J.;López,T.;álvarez,M.;Aguilar,H.;Quintana,P.J.NonCryst.Solids 2008,354,729.doi:10.1016/j.jnoncrysol.2007.07.074

    (38) Kanagadurai,R.;Sankar,R.;Sivanesan,G.;Srinivasan,S.;Rajasekaran,R.;Jayavel,R.Mater.Chem.Phys.2008,108,170.doi:10.1016/j.matchemphys.2007.09.041

    (40)Ge,M.;Liu,L.;Chen,W.;Zhou,Z.CrysEngComm 2012,14,1038.doi:10.1039/c1ce06264f

    (41) Fan,H.M.;Jiang,T.F.;Wang,D.J.;Wang,L.L.;Zhai,J.L.;He,D.Q.;Wang,P.;Xie,T.F.J.Phys.Chem.C 2012,116,2425.doi:10.1021/jp206798d

    猜你喜歡
    花形化工學(xué)院物理化學(xué)
    使固態(tài)化學(xué)反應(yīng)100%完成的方法
    春風(fēng)自愛鬧花草
    世界博覽(2023年8期)2023-04-22 15:23:50
    物理化學(xué)課程教學(xué)改革探索
    云南化工(2021年9期)2021-12-21 07:44:16
    物理化學(xué)課堂教學(xué)改進(jìn)的探索
    云南化工(2021年6期)2021-12-21 07:31:42
    國家開放大學(xué)石油和化工學(xué)院學(xué)習(xí)中心列表
    【鏈接】國家開放大學(xué)石油和化工學(xué)院學(xué)習(xí)中心(第四批)名單
    Chemical Concepts from Density Functional Theory
    感知6以內(nèi)的數(shù)量
    觀花解語
    《化工學(xué)報》贊助單位
    欧美成人免费av一区二区三区| 久久国产精品影院| 一卡2卡三卡四卡精品乱码亚洲| 欧美乱妇无乱码| 国产精品爽爽va在线观看网站| 国产一区在线观看成人免费| 日本免费一区二区三区高清不卡| 亚洲成人精品中文字幕电影| 免费看a级黄色片| 人人妻,人人澡人人爽秒播| 一边摸一边做爽爽视频免费| 人妻夜夜爽99麻豆av| 手机成人av网站| 久久精品国产综合久久久| 亚洲中文日韩欧美视频| 天堂影院成人在线观看| 人妻久久中文字幕网| 黄色片一级片一级黄色片| 最近最新免费中文字幕在线| 精品久久久久久久毛片微露脸| 美女大奶头视频| 老汉色∧v一级毛片| 亚洲av成人一区二区三| 欧美人与性动交α欧美精品济南到| 久久精品成人免费网站| 午夜亚洲福利在线播放| 欧美性猛交╳xxx乱大交人| 亚洲国产欧美人成| 丰满的人妻完整版| 巨乳人妻的诱惑在线观看| 欧美日本亚洲视频在线播放| 国产三级在线视频| 99re在线观看精品视频| 亚洲成人中文字幕在线播放| 男女午夜视频在线观看| 久久婷婷成人综合色麻豆| 999精品在线视频| 成年版毛片免费区| 韩国av一区二区三区四区| 窝窝影院91人妻| 国产亚洲精品av在线| 国产精品国产高清国产av| 成人欧美大片| 亚洲精品国产一区二区精华液| 亚洲欧美激情综合另类| 欧美日韩福利视频一区二区| 麻豆av在线久日| 国产精品av久久久久免费| 免费电影在线观看免费观看| 五月伊人婷婷丁香| 亚洲精品一区av在线观看| 国产主播在线观看一区二区| 久久精品国产清高在天天线| 神马国产精品三级电影在线观看 | 精品一区二区三区视频在线观看免费| 亚洲午夜理论影院| 久久久精品大字幕| 99热这里只有精品一区 | 欧美黄色片欧美黄色片| 日韩欧美精品v在线| 亚洲精品中文字幕在线视频| 日本熟妇午夜| 看片在线看免费视频| 久久国产精品人妻蜜桃| 亚洲熟妇熟女久久| av超薄肉色丝袜交足视频| 国模一区二区三区四区视频 | 琪琪午夜伦伦电影理论片6080| 久久中文看片网| 国产高清激情床上av| 国产主播在线观看一区二区| 亚洲成人精品中文字幕电影| www日本黄色视频网| 久久精品aⅴ一区二区三区四区| 欧美又色又爽又黄视频| 波多野结衣高清无吗| 精品国产超薄肉色丝袜足j| 国产精品免费视频内射| 亚洲av五月六月丁香网| 欧美日本视频| 国产亚洲精品综合一区在线观看 | 国内揄拍国产精品人妻在线| 亚洲国产精品sss在线观看| 欧美又色又爽又黄视频| 999久久久国产精品视频| 在线观看www视频免费| 变态另类成人亚洲欧美熟女| 色老头精品视频在线观看| 国产精品亚洲一级av第二区| 国产精品久久久久久亚洲av鲁大| 亚洲欧美日韩无卡精品| 成人三级黄色视频| 国产真人三级小视频在线观看| 91麻豆精品激情在线观看国产| 国产欧美日韩精品亚洲av| 久久精品综合一区二区三区| 国产黄a三级三级三级人| 久久香蕉国产精品| 久久久国产精品麻豆| 免费看美女性在线毛片视频| 欧美日韩乱码在线| 成人午夜高清在线视频| 国产成人精品久久二区二区91| 日韩大码丰满熟妇| 亚洲av熟女| 1024视频免费在线观看| 久久精品国产亚洲av高清一级| 国产精品自产拍在线观看55亚洲| 黄色视频不卡| 国产成年人精品一区二区| 免费av毛片视频| 日韩欧美一区二区三区在线观看| 国产欧美日韩一区二区三| 精品国产美女av久久久久小说| 婷婷六月久久综合丁香| 亚洲激情在线av| 亚洲av美国av| 亚洲精品美女久久av网站| 亚洲国产欧洲综合997久久,| 国产精品一区二区三区四区久久| 欧美日韩亚洲综合一区二区三区_| 午夜亚洲福利在线播放| 国产亚洲精品久久久久5区| 国产黄色小视频在线观看| 日韩av在线大香蕉| 这个男人来自地球电影免费观看| 在线观看免费日韩欧美大片| 久久久国产成人免费| 国产麻豆成人av免费视频| 亚洲欧美激情综合另类| 性欧美人与动物交配| 国产69精品久久久久777片 | 久久久国产成人免费| 亚洲色图 男人天堂 中文字幕| 亚洲成av人片免费观看| 亚洲一卡2卡3卡4卡5卡精品中文| 国产精品美女特级片免费视频播放器 | 国产亚洲精品久久久久久毛片| 国产精品1区2区在线观看.| 欧美成人午夜精品| 国产爱豆传媒在线观看 | 欧美乱妇无乱码| 国内精品久久久久久久电影| 蜜桃久久精品国产亚洲av| 9191精品国产免费久久| 久久精品国产综合久久久| 国产精品99久久99久久久不卡| 国产午夜福利久久久久久| 少妇粗大呻吟视频| 亚洲国产精品sss在线观看| 一区福利在线观看| 视频区欧美日本亚洲| 啪啪无遮挡十八禁网站| 老司机午夜十八禁免费视频| 99热这里只有精品一区 | 久久久久国内视频| 99久久国产精品久久久| 亚洲av电影不卡..在线观看| 男女那种视频在线观看| 亚洲自偷自拍图片 自拍| 国产免费av片在线观看野外av| 美女免费视频网站| 波多野结衣高清作品| 搡老妇女老女人老熟妇| 禁无遮挡网站| 性欧美人与动物交配| 国产成人啪精品午夜网站| 国产探花在线观看一区二区| 看免费av毛片| 无限看片的www在线观看| 亚洲电影在线观看av| 色在线成人网| 日韩精品免费视频一区二区三区| 88av欧美| 99国产综合亚洲精品| 十八禁人妻一区二区| 可以在线观看的亚洲视频| 国产成人欧美在线观看| 日日摸夜夜添夜夜添小说| 亚洲欧美日韩东京热| 国产乱人伦免费视频| 久久香蕉精品热| 国内少妇人妻偷人精品xxx网站 | 麻豆成人av在线观看| 成人特级黄色片久久久久久久| 夜夜看夜夜爽夜夜摸| 99久久久亚洲精品蜜臀av| 午夜福利在线在线| 巨乳人妻的诱惑在线观看| 免费av毛片视频| 哪里可以看免费的av片| 亚洲狠狠婷婷综合久久图片| 国产成人精品无人区| 黄片大片在线免费观看| 欧美日韩一级在线毛片| 欧美色欧美亚洲另类二区| 欧美日韩亚洲国产一区二区在线观看| 黄色丝袜av网址大全| 国产亚洲精品一区二区www| 两个人的视频大全免费| 欧美日本亚洲视频在线播放| АⅤ资源中文在线天堂| 两性夫妻黄色片| 桃色一区二区三区在线观看| 日韩欧美在线二视频| 成人精品一区二区免费| 国产精品1区2区在线观看.| 日韩免费av在线播放| 国产精品久久久人人做人人爽| 最近视频中文字幕2019在线8| 中亚洲国语对白在线视频| 国产成人一区二区三区免费视频网站| 国产激情久久老熟女| 看黄色毛片网站| 国产精品亚洲一级av第二区| 欧美+亚洲+日韩+国产| 丰满的人妻完整版| 少妇人妻一区二区三区视频| 黄色女人牲交| 国产精品久久久久久亚洲av鲁大| 91麻豆精品激情在线观看国产| 亚洲性夜色夜夜综合| 欧美乱妇无乱码| 精品无人区乱码1区二区| 国产久久久一区二区三区| 麻豆一二三区av精品| 国产黄片美女视频| 亚洲精品在线观看二区| 亚洲av美国av| 色播亚洲综合网| bbb黄色大片| 精品久久久久久久久久久久久| 欧美日本视频| 久久精品91蜜桃| 美女午夜性视频免费| av有码第一页| www.www免费av| 欧美成人免费av一区二区三区| 国产1区2区3区精品| 精品不卡国产一区二区三区| 午夜福利18| 久久精品综合一区二区三区| 在线观看午夜福利视频| 首页视频小说图片口味搜索| 一级毛片精品| 亚洲国产高清在线一区二区三| 国产一区在线观看成人免费| 成在线人永久免费视频| 国产成人一区二区三区免费视频网站| 午夜精品一区二区三区免费看| 一边摸一边做爽爽视频免费| 国产真人三级小视频在线观看| 亚洲欧美一区二区三区黑人| 一卡2卡三卡四卡精品乱码亚洲| 色综合婷婷激情| 每晚都被弄得嗷嗷叫到高潮| 十八禁网站免费在线| 麻豆国产av国片精品| 怎么达到女性高潮| 精品国产亚洲在线| 少妇被粗大的猛进出69影院| 人成视频在线观看免费观看| 人妻久久中文字幕网| 不卡av一区二区三区| 午夜福利欧美成人| 国产亚洲精品久久久久5区| 黄色片一级片一级黄色片| 精品国产乱子伦一区二区三区| 久久香蕉精品热| 国内揄拍国产精品人妻在线| 日日干狠狠操夜夜爽| 亚洲成a人片在线一区二区| 男男h啪啪无遮挡| 国产精品久久久久久久电影 | 90打野战视频偷拍视频| av超薄肉色丝袜交足视频| 久久久久国产一级毛片高清牌| 特级一级黄色大片| 亚洲 国产 在线| 99在线人妻在线中文字幕| 国产熟女午夜一区二区三区| 亚洲在线自拍视频| 国产精品免费视频内射| 日本 av在线| 亚洲精品久久国产高清桃花| 熟女少妇亚洲综合色aaa.| 亚洲自偷自拍图片 自拍| 亚洲真实伦在线观看| 最近视频中文字幕2019在线8| 亚洲成人久久爱视频| 99国产精品99久久久久| 亚洲专区中文字幕在线| 亚洲无线在线观看| 国产麻豆成人av免费视频| 国产精品野战在线观看| 国内少妇人妻偷人精品xxx网站 | 深夜精品福利| 黄片大片在线免费观看| 国产99久久九九免费精品| 97碰自拍视频| 岛国在线免费视频观看| 国产久久久一区二区三区| 国产视频一区二区在线看| 波多野结衣高清作品| 精品无人区乱码1区二区| 一本综合久久免费| 国产一区在线观看成人免费| 欧美成人一区二区免费高清观看 | 成人欧美大片| 午夜影院日韩av| 母亲3免费完整高清在线观看| 两个人看的免费小视频| 日韩欧美 国产精品| 亚洲熟妇熟女久久| 又爽又黄无遮挡网站| 久久久久免费精品人妻一区二区| 神马国产精品三级电影在线观看 | 男男h啪啪无遮挡| 国产男靠女视频免费网站| 久久人妻福利社区极品人妻图片| 久久久国产成人精品二区| 欧美日韩瑟瑟在线播放| 国产主播在线观看一区二区| 日韩高清综合在线| 日日夜夜操网爽| 伊人久久大香线蕉亚洲五| 男女之事视频高清在线观看| 亚洲欧美精品综合久久99| 一边摸一边做爽爽视频免费| 久久精品影院6| 午夜激情福利司机影院| 久久精品国产综合久久久| 美女大奶头视频| 欧美成人一区二区免费高清观看 | 欧美一级a爱片免费观看看 | 成人av在线播放网站| 国产激情偷乱视频一区二区| 大型黄色视频在线免费观看| 最近视频中文字幕2019在线8| 这个男人来自地球电影免费观看| 午夜成年电影在线免费观看| 亚洲欧美日韩东京热| 天天躁夜夜躁狠狠躁躁| 亚洲性夜色夜夜综合| 首页视频小说图片口味搜索| 老熟妇乱子伦视频在线观看| 男女做爰动态图高潮gif福利片| 久久精品成人免费网站| 亚洲 欧美一区二区三区| 国产三级中文精品| 精品免费久久久久久久清纯| 国产激情久久老熟女| 在线观看免费视频日本深夜| 美女高潮喷水抽搐中文字幕| 禁无遮挡网站| 99久久99久久久精品蜜桃| av国产免费在线观看| 亚洲精华国产精华精| 淫妇啪啪啪对白视频| 男女午夜视频在线观看| 久久久久久久精品吃奶| 淫妇啪啪啪对白视频| 村上凉子中文字幕在线| 国产精品久久久久久人妻精品电影| 午夜久久久久精精品| 悠悠久久av| 欧美日韩乱码在线| 99热这里只有精品一区 | 午夜久久久久精精品| 999久久久国产精品视频| 国内毛片毛片毛片毛片毛片| 中出人妻视频一区二区| 黑人巨大精品欧美一区二区mp4| 日韩三级视频一区二区三区| 亚洲一区高清亚洲精品| 又紧又爽又黄一区二区| 国产午夜精品久久久久久| 久久久久国产一级毛片高清牌| 国产亚洲精品久久久久久毛片| www.999成人在线观看| 老司机午夜十八禁免费视频| 女同久久另类99精品国产91| 1024香蕉在线观看| 午夜精品久久久久久毛片777| 亚洲av成人一区二区三| 男人舔女人下体高潮全视频| 99在线视频只有这里精品首页| 变态另类成人亚洲欧美熟女| 成在线人永久免费视频| 亚洲国产中文字幕在线视频| 日韩欧美国产一区二区入口| 中亚洲国语对白在线视频| 国产av麻豆久久久久久久| 美女大奶头视频| 青草久久国产| 91九色精品人成在线观看| 久久精品夜夜夜夜夜久久蜜豆 | 国产高清videossex| 国内少妇人妻偷人精品xxx网站 | 舔av片在线| 日本三级黄在线观看| 少妇粗大呻吟视频| 亚洲av第一区精品v没综合| 国产精品av视频在线免费观看| 在线观看日韩欧美| 色老头精品视频在线观看| 欧美黄色片欧美黄色片| 亚洲人与动物交配视频| 欧美性长视频在线观看| 免费在线观看完整版高清| 少妇的丰满在线观看| 在线a可以看的网站| 九色成人免费人妻av| www国产在线视频色| 在线a可以看的网站| 露出奶头的视频| 国产激情久久老熟女| 精品国产超薄肉色丝袜足j| 国产精品爽爽va在线观看网站| 91大片在线观看| 最好的美女福利视频网| 禁无遮挡网站| 欧美日本视频| 国产av一区二区精品久久| 国产熟女午夜一区二区三区| 国产午夜精品论理片| 草草在线视频免费看| 亚洲一卡2卡3卡4卡5卡精品中文| 国产精品亚洲美女久久久| 神马国产精品三级电影在线观看 | 国产成人av激情在线播放| 丁香欧美五月| 亚洲成人久久爱视频| 国产黄片美女视频| 女生性感内裤真人,穿戴方法视频| 久久精品国产99精品国产亚洲性色| 国产亚洲精品久久久久久毛片| 性色av乱码一区二区三区2| 久久人妻av系列| 亚洲自拍偷在线| 国产精华一区二区三区| 免费在线观看视频国产中文字幕亚洲| 18禁国产床啪视频网站| 国产精品亚洲av一区麻豆| 久久香蕉精品热| 国产黄色小视频在线观看| 免费在线观看日本一区| 国产高清激情床上av| 精品无人区乱码1区二区| 黑人巨大精品欧美一区二区mp4| 久久久国产精品麻豆| 久久久久精品国产欧美久久久| 大型黄色视频在线免费观看| 色精品久久人妻99蜜桃| 91九色精品人成在线观看| 老汉色av国产亚洲站长工具| www.精华液| 村上凉子中文字幕在线| 久久性视频一级片| 两性午夜刺激爽爽歪歪视频在线观看 | 一进一出好大好爽视频| 非洲黑人性xxxx精品又粗又长| 亚洲欧美精品综合一区二区三区| 欧美日韩中文字幕国产精品一区二区三区| 亚洲欧美精品综合久久99| 妹子高潮喷水视频| 国产亚洲精品久久久久5区| 日本一本二区三区精品| 中文字幕人成人乱码亚洲影| 三级毛片av免费| 特级一级黄色大片| 久久这里只有精品中国| 99精品久久久久人妻精品| 日日摸夜夜添夜夜添小说| 人人妻人人澡欧美一区二区| 黄片大片在线免费观看| 不卡av一区二区三区| 哪里可以看免费的av片| 国产激情久久老熟女| www.自偷自拍.com| 日韩大码丰满熟妇| 成人高潮视频无遮挡免费网站| 色综合站精品国产| 精品一区二区三区av网在线观看| 少妇被粗大的猛进出69影院| 成年女人毛片免费观看观看9| 两个人的视频大全免费| 久久精品成人免费网站| 99国产精品一区二区三区| 哪里可以看免费的av片| 日本在线视频免费播放| 一级a爱片免费观看的视频| 午夜老司机福利片| 大型黄色视频在线免费观看| 国产亚洲av嫩草精品影院| 久久国产精品影院| 欧美zozozo另类| netflix在线观看网站| 亚洲男人天堂网一区| 婷婷丁香在线五月| 天天躁夜夜躁狠狠躁躁| 成人手机av| 日本成人三级电影网站| 51午夜福利影视在线观看| 男男h啪啪无遮挡| 亚洲熟妇熟女久久| 亚洲 欧美一区二区三区| 天堂动漫精品| 制服人妻中文乱码| av欧美777| 国产单亲对白刺激| 欧美+亚洲+日韩+国产| 毛片女人毛片| 精品少妇一区二区三区视频日本电影| 亚洲九九香蕉| 99国产精品99久久久久| 欧美黑人欧美精品刺激| 一本精品99久久精品77| 国产高清激情床上av| 精品欧美一区二区三区在线| 日本免费一区二区三区高清不卡| 91国产中文字幕| 老司机在亚洲福利影院| 极品教师在线免费播放| 国产午夜精品论理片| 免费看美女性在线毛片视频| 欧美日本视频| 国内毛片毛片毛片毛片毛片| 久久 成人 亚洲| 天堂动漫精品| 久久热在线av| 久久99热这里只有精品18| 校园春色视频在线观看| 亚洲欧美日韩无卡精品| 亚洲欧美激情综合另类| 一区二区三区高清视频在线| 两性夫妻黄色片| 久久香蕉精品热| 免费看十八禁软件| 国产亚洲精品久久久久久毛片| 最近最新免费中文字幕在线| 老司机深夜福利视频在线观看| 久久久久久大精品| 欧美高清成人免费视频www| videosex国产| 亚洲av中文字字幕乱码综合| 国产三级黄色录像| 怎么达到女性高潮| 男女床上黄色一级片免费看| 两个人看的免费小视频| 国产精品一及| 国产片内射在线| 国产精品av视频在线免费观看| 在线播放国产精品三级| 国内揄拍国产精品人妻在线| 在线国产一区二区在线| 亚洲18禁久久av| 人妻丰满熟妇av一区二区三区| 91麻豆精品激情在线观看国产| 国产激情久久老熟女| 巨乳人妻的诱惑在线观看| 国产97色在线日韩免费| 日韩欧美国产一区二区入口| 热99re8久久精品国产| 日韩精品青青久久久久久| 久久久精品国产亚洲av高清涩受| 亚洲专区中文字幕在线| 精品熟女少妇八av免费久了| 精品电影一区二区在线| 91国产中文字幕| 熟女电影av网| 午夜福利视频1000在线观看| 日本黄色视频三级网站网址| 一本久久中文字幕| 夜夜看夜夜爽夜夜摸| 禁无遮挡网站| 精品一区二区三区视频在线观看免费| 久久久久九九精品影院| 久热爱精品视频在线9| 欧美成人一区二区免费高清观看 | 亚洲av中文字字幕乱码综合| 麻豆国产97在线/欧美 | 成人特级黄色片久久久久久久| 国产精品久久视频播放| 久久国产精品影院| 在线观看午夜福利视频| 亚洲专区国产一区二区| 中国美女看黄片| 全区人妻精品视频| 欧美乱妇无乱码| 国产爱豆传媒在线观看 | 在线观看www视频免费| 制服诱惑二区| 18禁观看日本| 免费在线观看成人毛片| 无遮挡黄片免费观看| 精品久久蜜臀av无| 日韩 欧美 亚洲 中文字幕| 亚洲第一欧美日韩一区二区三区| 美女午夜性视频免费| 日韩欧美在线二视频| 色综合亚洲欧美另类图片| 九色国产91popny在线| 亚洲av美国av| 国产探花在线观看一区二区| 亚洲精品美女久久av网站| 一级毛片高清免费大全| 欧美性猛交黑人性爽| 在线观看舔阴道视频| 狠狠狠狠99中文字幕| 亚洲精品一卡2卡三卡4卡5卡| a在线观看视频网站| 色哟哟哟哟哟哟| 女警被强在线播放| 亚洲精品在线观看二区|