Rational tuning of crystallographic surface and metal doping were effective to enhance the catalytic performance of metal organic frameworks,but limited work has been explored for achieving modulation of crystal facet...Rational tuning of crystallographic surface and metal doping were effective to enhance the catalytic performance of metal organic frameworks,but limited work has been explored for achieving modulation of crystal facets and metal doping in a single system.MIL-68(In)was promising for photocatalytic applications due to its low toxicity and excellent photoresponsivity.However,its catalytic activity was constrained by severe carrier recombination and a lack of active sites.Herein,increased(001)facet ratio and active sites exposure were simultaneously realized by cobalt doping in MIL-68(In)through a one-pot solvothermal strategy.Optimized MIL-68(In/Co)-2.5 exhibited remarkable catalytic performance in comparison with pristine MIL-68(In)and other MIL-68(In/Co).The reaction kinetic constant and degradation efficiency of MIL-68(In/Co)were approximately twice and 17%higher than the pristine MIL-68(In)in 36 min reaction,respectively.Density functional theory calculations revealed that Co dopant could modulate the orientation of MIL-68(In)facets,facilitate the exchange of electrons and reduce the adsorption energy of peroxymonosulfate(PMS).This work provides a novel pathway for improvement of In-based MOFs in PMS/vis system,it also promotes the profound comprehension of the correlation between crystal facet regulation and catalytic activation in the PMS/vis system.展开更多
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 photodegra...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.展开更多
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 exte...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.展开更多
Anatase titanium(IV)oxide(TiO_(2))particles with exposed{001}and{101}facets were prepared by hydrothermal treatment of amorphous TiO_(2) with H_(2)O_(2)-NH_(3) solution.Crystal phase,shape,and size of TiO_(2) particle...Anatase titanium(IV)oxide(TiO_(2))particles with exposed{001}and{101}facets were prepared by hydrothermal treatment of amorphous TiO_(2) with H_(2)O_(2)-NH_(3) solution.Crystal phase,shape,and size of TiO_(2) particles are found to be greatly dependent on the ratio of H_(2)O_(2)-NH_(3) solution.The prepared TiO_(2) particles with specific exposed crystal faces show higher photocatalytic activity for acetaldehyde decomposition than commercial spherical TiO_(2) particles.This result implies that recombination is prevented by spatial separation of redox sites in the particles because of selective migration of electrons and positive holes to specific exposed crystal faces and/or different reactivity of electrons and positive holes on the specific exposed crystal face.展开更多
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 ...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.展开更多
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 excelle...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.展开更多
Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(...Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(2)O_(5))are rationally synthesized through topotactic conversion.Specifically,F-Nb_(2)O_(5) are assembled by single-crystal nanoflakes with nearly 97%exposed(100)facet,which maximizes the exposure of the feasible Li^(+)transport pathways along loosely packed 4g atomic layers to the electrolytes,thus effectively enhancing the Li^(+)-intercalation performance.Besides,the band gap of F-Nb_(2)O_(5) is reduced to 2.87 eV due to the doping of F atoms,leading to enhanced electrical conductivity.The synergetic effects between tailored exposed crystal facets,F-doping,and ultrathin building blocks,speed up the Li^(+)/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb_(2)O_(5).Therefore,F-Nb_(2)O_(5) exhibit superior rate capability(210.8 and 164.9 mAh g^(-1) at 1 and 10 C,respectively)and good long-term 10 C cycling performance(132.7 mAh g^(-1) after 1500 cycles).展开更多
Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is st...Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.展开更多
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 t...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.展开更多
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...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.展开更多
It is known that exposed surface determines material’s performance.WO3 is widely used in gas sensing and its working surface is proposed to control its sensitivity.However,the working surface,or most exposed surface ...It is known that exposed surface determines material’s performance.WO3 is widely used in gas sensing and its working surface is proposed to control its sensitivity.However,the working surface,or most exposed surface with detailed surface structure remain unclear.In this paper,DFT calculation confirmed that oxygen vacancy O-terminated surface is the most exposed hexagonal WO3(001)surface,judging from competitive adsorption of CO and O2,working surface determination for CO sensing and comparison of oxygen vacancy formation ene rgies on different h-WO3(001)surfaces.It is found that DFT can be a useful alternate for exposed surface determination.Our results provide new perspectives and performance explanations for material research.展开更多
Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline T...Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline TiO_(2)film,hi-layered dye-sensitized solar cells(DSSCs)have been fabricated by electrophoresis deposition method,which well preserved the fragile hierarchical structure.Owing to the superior dye adsorption and light scattering effect of HSs,an overall energy conversion efficiency of 7.38%is achieved,which is 26%higher than that of nanoparticle-based photoanode.展开更多
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 wa...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.展开更多
{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 m...{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.展开更多
The nanoscale zinc oxide(n-ZnO)was used in food packages due to its superior antibac terial activity,resulting in potential intake of n-ZnO through the digestive system,wherein n-ZnO interacted with saliva.In recent,f...The nanoscale zinc oxide(n-ZnO)was used in food packages due to its superior antibac terial activity,resulting in potential intake of n-ZnO through the digestive system,wherein n-ZnO interacted with saliva.In recent,facet engineering,a technique for controlling the exposed facets,was applied to n-ZnO,whereas risk of n-ZnO with specific exposed facets in saliva was ignored.ZnO nanoflakes(ZnO-0001)and nanoneedles(ZnO-1010)with the pri mary exposed facets of{0001}and{1010}respectively were prepared in this study,investigat ing stability and toxicity of ZnO-0001 and ZnO-1010 in synthetic saliva.Both ZnO-0001 and ZnO-1010 partially transformed into amorphous Zn_(3)(PO_(4))_(2)within 1 hr in the saliva even containing orgnaic components,forming a ZnO-Zn_(3)(PO_(4))_(2)core-shell structure.Neverthe less,ZnO-1010 relative to ZnO-0001 would likely transform into Zn_(3)(PO_(4))_(2),being attributed to superior dissolution of{1010}facet due to its lower vacancy formation energy(1.15 eV than{0001}facet(3.90 eV)).The toxicity of n-ZnO to Caco-2 cells was also dependent on the primary exposed facet;ZnO-0001 caused cell toxicity through oxidative stress,whereas ZnO-1010 resulted in lower cells viability than ZnO-0001 through oxidative stress and mem brane damage.Density functional theory calculations illustrated that·O_(2)^(-)was formed and released on{1010}facet,yet O_(2)^(2-)instead of·O_(2)^(-)was generated on{0001}facet,leading to low oxidative stress from ZnO-0001.All findings demonstrated that stability and toxicity of n-ZnO were dependent on the primary exposed facet,improving our understanding o health risk of nanomaterials.展开更多
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...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.展开更多
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 nitrog...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.展开更多
Anatase TiO2 with a variant percentage of exposed （001） facets was prepared under hydrothermal processes by adjusting the volume of HF, and the photocatalytic mechanism was studied from atomic-molecular scale by HRT...Anatase TiO2 with a variant percentage of exposed （001） facets was prepared under hydrothermal processes by adjusting the volume of HF, and the photocatalytic mechanism was studied from atomic-molecular scale by HRTEM and Raman spectroscopy. It was revealed that： 1） From HRTEM observations, the surface of original TiO2 with exposed （001） facets was clean without impurity, and the crystal lattice was clear and completed; however, when mixed with methylene blue （MB） solution, there were many 1 nm molecular absorbed at the surface of TiO2; after the photocatalytic experiment, MB molecules disappeared and the TiO2 lattice image became fuzzy. 2） The broken path of the MB chemical bond was obtained by Raman spectroscopy, i.e., after the irradiation of the light, the vibrational mode of C-N-C disappeared due to the chemical bond breakage, and the groups containing C-N bond and carbon rings were gradually decomposed. Accordingly, we propose that the driving force for breaking the chemical bond and the disappearance of groups is from the surface lattice distortion of TiO2 during photocatalyzation.展开更多
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 mesocrystal...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.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52100087,52170079,U20A20322)Science and Technology Development Program of Jilin Province,China(Nos.20220508100RC,20230402035GH).
文摘Rational tuning of crystallographic surface and metal doping were effective to enhance the catalytic performance of metal organic frameworks,but limited work has been explored for achieving modulation of crystal facets and metal doping in a single system.MIL-68(In)was promising for photocatalytic applications due to its low toxicity and excellent photoresponsivity.However,its catalytic activity was constrained by severe carrier recombination and a lack of active sites.Herein,increased(001)facet ratio and active sites exposure were simultaneously realized by cobalt doping in MIL-68(In)through a one-pot solvothermal strategy.Optimized MIL-68(In/Co)-2.5 exhibited remarkable catalytic performance in comparison with pristine MIL-68(In)and other MIL-68(In/Co).The reaction kinetic constant and degradation efficiency of MIL-68(In/Co)were approximately twice and 17%higher than the pristine MIL-68(In)in 36 min reaction,respectively.Density functional theory calculations revealed that Co dopant could modulate the orientation of MIL-68(In)facets,facilitate the exchange of electrons and reduce the adsorption energy of peroxymonosulfate(PMS).This work provides a novel pathway for improvement of In-based MOFs in PMS/vis system,it also promotes the profound comprehension of the correlation between crystal facet regulation and catalytic activation in the PMS/vis system.
基金supported by the National Natural Science Foundation of China(Nos.21406164,21466035 and 51203111)the National Basic Research Program of China("973"Program,Nos.2012CB720100 and 2014CB239300)
文摘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.
文摘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.
基金financially supported by the Programs of Japan Science and Technology Agency:Promoting Individual Research to Nature the Seeds of Future Innovation and Organizing the Unique and Innovative Network,and Advanced Catalytic Transformation Program for Carbon Utilization
文摘Anatase titanium(IV)oxide(TiO_(2))particles with exposed{001}and{101}facets were prepared by hydrothermal treatment of amorphous TiO_(2) with H_(2)O_(2)-NH_(3) solution.Crystal phase,shape,and size of TiO_(2) particles are found to be greatly dependent on the ratio of H_(2)O_(2)-NH_(3) solution.The prepared TiO_(2) particles with specific exposed crystal faces show higher photocatalytic activity for acetaldehyde decomposition than commercial spherical TiO_(2) particles.This result implies that recombination is prevented by spatial separation of redox sites in the particles because of selective migration of electrons and positive holes to specific exposed crystal faces and/or different reactivity of electrons and positive holes on the specific exposed crystal face.
基金supported by the National Key R&D Program of China(2016YFC0204100)the Zhejiang Provincial "151" Talents Program+1 种基金the Program for Zhejiang Leading Team of S&T Innovation(2013TD07)the Changjiang Scholar Incentive Program(2009)~~
文摘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.
基金financially supported by the National Natural Science Foundation of China(Nos.51773226,61701514)the Natural Science Foundation of Hunan Province(No.2018JJ3603)
文摘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.
基金supported by the National Natural Science Foundation of China(No.51802163)the Natural Science Foundation of Henan Province of China(No.222300420252)the Natural Science Foundation of Henan Department of Education(No.20A480004).
文摘Orthorhombic Nb_(2)O_(5)(T-Nb_(2)O_(5))is attractive for fast-charging Li-ion batteries,but it is still hard to realize rapid charge transfer kinetics for Li-ion storage.Herein,F-doped T-Nb_(2)O_(5) microflowers(F-Nb_(2)O_(5))are rationally synthesized through topotactic conversion.Specifically,F-Nb_(2)O_(5) are assembled by single-crystal nanoflakes with nearly 97%exposed(100)facet,which maximizes the exposure of the feasible Li^(+)transport pathways along loosely packed 4g atomic layers to the electrolytes,thus effectively enhancing the Li^(+)-intercalation performance.Besides,the band gap of F-Nb_(2)O_(5) is reduced to 2.87 eV due to the doping of F atoms,leading to enhanced electrical conductivity.The synergetic effects between tailored exposed crystal facets,F-doping,and ultrathin building blocks,speed up the Li^(+)/electron transfer kinetics and improve the pseudocapacitive properties of F-Nb_(2)O_(5).Therefore,F-Nb_(2)O_(5) exhibit superior rate capability(210.8 and 164.9 mAh g^(-1) at 1 and 10 C,respectively)and good long-term 10 C cycling performance(132.7 mAh g^(-1) after 1500 cycles).
文摘Photocatalytic degradation of gaseous pollutants on Bi-based semiconductors under solar lightirradiation has attracted significant attention.However,their application in gaseous straight-chainalkane purification is still rare.Here,a series of Bi/BiOBr composites were solvothermally synthe-sized and applied in solar-light-driven photocatalytic degradation of gaseous n-hexane.The charac-terization results revealed that both increasing number of functional groups of alcohol solvent(from methanol and ethylene glycol to glycerol)and solvothermal temperature(from 160 and 180to 200℃)facilitated the in-situ formation of metallic Bi nanospheres on BiOBr nanoplates withexposed(110)facets.Meanwhile,chemical bonding between Bi and BiOBr was observed on theseexposed facets that resulted in the formation of surface oxygen vacancy.Furthermore,the synergis-tic effect of optimum surface oxygen vacancy on exposed(110)facets led to a high visible light re-sponse,narrow band gap,great photocurrent,low recombination rate of the charge carriers,andstrong·O2-and h*formation,all of which resulted in the highest removal efficiency of 97.4%within120 min of 15 ppmv of n-hexane on Bi/BiOBr.Our findings efficiently broaden the application ofBi-based photocatalysis technology in the purification of gaseous straight-chain pollutants emittedby the petrochemical industry.
文摘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.
基金financially supported by the National Natural Science Foundation of China(Nos.61434002,51571135)National Science Foundation of United States(Nos.DMR-1104994,CBET-1510121)+2 种基金Shanxi Scholars Program(No.[2012]12)"One Hundred Talented People"of Shanxi ProvinceShanxi Province Foundations(Nos.[2012]10,[2013]9)
文摘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.
基金supported by National Natural Science Foundation of China(Nos.61971252,20703027)Excellent Youth Fund of Shandong Province(No.ZR201709200070)+2 种基金Foundation of Shandong Educational Committee(No.J09LB06)Shandong excellent young scientist research award fund(No.BS2011NJ004)open project of Shanghai Key Laboratory of Rare Earth Functional Materials。
文摘It is known that exposed surface determines material’s performance.WO3 is widely used in gas sensing and its working surface is proposed to control its sensitivity.However,the working surface,or most exposed surface with detailed surface structure remain unclear.In this paper,DFT calculation confirmed that oxygen vacancy O-terminated surface is the most exposed hexagonal WO3(001)surface,judging from competitive adsorption of CO and O2,working surface determination for CO sensing and comparison of oxygen vacancy formation ene rgies on different h-WO3(001)surfaces.It is found that DFT can be a useful alternate for exposed surface determination.Our results provide new perspectives and performance explanations for material research.
文摘Anatase Ti0_(2) nanosheet-based hierarchical spheres(HSs)with nearly 100%exposed{001}facets were synthesized via a facile solvothermal process.Using these hierarchical spheres as a scattering layer on nanocrystaline TiO_(2)film,hi-layered dye-sensitized solar cells(DSSCs)have been fabricated by electrophoresis deposition method,which well preserved the fragile hierarchical structure.Owing to the superior dye adsorption and light scattering effect of HSs,an overall energy conversion efficiency of 7.38%is achieved,which is 26%higher than that of nanoparticle-based photoanode.
基金the National Natural Science Foundation of China (U1632273, 21673214,U1732272, U1832165).
文摘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.
基金This work is supported by the National Basic Research Program of China(No.2012CB9222000).
文摘{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.
基金supported by the National Natural Science Foundation of China(Nos.21806141,22021003,and 21976163)。
文摘The nanoscale zinc oxide(n-ZnO)was used in food packages due to its superior antibac terial activity,resulting in potential intake of n-ZnO through the digestive system,wherein n-ZnO interacted with saliva.In recent,facet engineering,a technique for controlling the exposed facets,was applied to n-ZnO,whereas risk of n-ZnO with specific exposed facets in saliva was ignored.ZnO nanoflakes(ZnO-0001)and nanoneedles(ZnO-1010)with the pri mary exposed facets of{0001}and{1010}respectively were prepared in this study,investigat ing stability and toxicity of ZnO-0001 and ZnO-1010 in synthetic saliva.Both ZnO-0001 and ZnO-1010 partially transformed into amorphous Zn_(3)(PO_(4))_(2)within 1 hr in the saliva even containing orgnaic components,forming a ZnO-Zn_(3)(PO_(4))_(2)core-shell structure.Neverthe less,ZnO-1010 relative to ZnO-0001 would likely transform into Zn_(3)(PO_(4))_(2),being attributed to superior dissolution of{1010}facet due to its lower vacancy formation energy(1.15 eV than{0001}facet(3.90 eV)).The toxicity of n-ZnO to Caco-2 cells was also dependent on the primary exposed facet;ZnO-0001 caused cell toxicity through oxidative stress,whereas ZnO-1010 resulted in lower cells viability than ZnO-0001 through oxidative stress and mem brane damage.Density functional theory calculations illustrated that·O_(2)^(-)was formed and released on{1010}facet,yet O_(2)^(2-)instead of·O_(2)^(-)was generated on{0001}facet,leading to low oxidative stress from ZnO-0001.All findings demonstrated that stability and toxicity of n-ZnO were dependent on the primary exposed facet,improving our understanding o health risk of nanomaterials.
基金This work was supported by the National Basic Research Program of China(No.2013CB632402)the National Natural Science Foundation of China(Nos.51272199,51320105001,51372190,and 21433007)+4 种基金Also,this work was financially supported by the Natural Science Foundation of Hubei Province of China(Nos.2015CFA001 and 2014CFB164)Deanship of Scientific Research(DSR)of King Abdulaziz University(No.90-130-35-HiCi)the Fundamental Research Funds for the Central Universities(Nos.WUT:2014-VII-010,2014-IV-058,2014-IV-155)Self-determined and Innova-tive Research Funds of SKLWUT(No.2013-ZD-1)a WUT Start-Up Grant.
文摘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.
文摘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.
文摘Anatase TiO2 with a variant percentage of exposed （001） facets was prepared under hydrothermal processes by adjusting the volume of HF, and the photocatalytic mechanism was studied from atomic-molecular scale by HRTEM and Raman spectroscopy. It was revealed that： 1） From HRTEM observations, the surface of original TiO2 with exposed （001） facets was clean without impurity, and the crystal lattice was clear and completed; however, when mixed with methylene blue （MB） solution, there were many 1 nm molecular absorbed at the surface of TiO2; after the photocatalytic experiment, MB molecules disappeared and the TiO2 lattice image became fuzzy. 2） The broken path of the MB chemical bond was obtained by Raman spectroscopy, i.e., after the irradiation of the light, the vibrational mode of C-N-C disappeared due to the chemical bond breakage, and the groups containing C-N bond and carbon rings were gradually decomposed. Accordingly, we propose that the driving force for breaking the chemical bond and the disappearance of groups is from the surface lattice distortion of TiO2 during photocatalyzation.
基金This work was supported by the National Natural Science Foundation of China(Nos.21473004 and 21673007)the National Basic Research Program of China(No.2013CB932601).
文摘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.
