Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of con...Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.展开更多
In the current research,a thorough examination unfolds concerning the attributes of magnetohydrodynamic(MHD)boundary layer flow and heat transfer inherent to nanoliquids derived from Sisko Al_(2)O_(3)-Eg and TiO_(2)-E...In the current research,a thorough examination unfolds concerning the attributes of magnetohydrodynamic(MHD)boundary layer flow and heat transfer inherent to nanoliquids derived from Sisko Al_(2)O_(3)-Eg and TiO_(2)-Eg compositions.Such nanoliquids are subjected to an extending surface.Consideration is duly given to slip boundary conditions,as well as the effects stemming from variable viscosity and variable thermal conductivity.The analytical approach applied involves the application of suitable similarity transformations.These conversions serve to transform the initial set of complex nonlinear partial differential equations into a more manageable assembly of ordinary differential equations.Through the utilization of the FEM,these reformulated equations are solved,considering the specified boundary conditions.The outcomes attained are graphically depicted by means of plots and tables.These visual aids facilitate a comprehensive exploration of how diverse parameters exert influence over the distributions of velocity,temperature,and concentration.Furthermore,detailed scrutiny is directed towards the fluctuations characterizing pivotal parameters,viz.,Nusselt number,skin-friction coefficient,and Sherwood number.It is identified that the Nusselt number showcases a diminishing trend coinciding with increasing values of the volume fraction parameter(φ).This trend remains consistent regardless of whether the nanoliquid under consideration is Al_(2)O_(3)-Eg or TiO_(2)-Eg based.In contrast,both the skin-friction coefficient and Sherwood number assume lower values as the volume fraction parameter(φ)escalates.This pattern remains congruent across both classifications of nanoliquids.The findings of the study impart valuable insights into the complex interplay governing the characteristics of HMT pertaining to Sisko Al_(2)O_(3)-Eg and TiO_(2)-Eg nanoliquids along an extending surface.展开更多
化工、纺织印染与农药化肥等产业的蓬勃发展推动着人类社会的进步,但同时也给环境治理带来了巨大难题。目前,光催化降解局限于在特定波长下针对单一有机污染物进行降解,然而现实中的情况往往更复杂。因此,开发一种多功能光催化材料用于...化工、纺织印染与农药化肥等产业的蓬勃发展推动着人类社会的进步,但同时也给环境治理带来了巨大难题。目前,光催化降解局限于在特定波长下针对单一有机污染物进行降解,然而现实中的情况往往更复杂。因此,开发一种多功能光催化材料用于光催化降解不同有机污染物显得尤为重要。采用一步无模板溶剂热法合成了核壳结构的C-TiO_(2)复合材料前驱体,并在氩气气氛下煅烧得到高结晶度的C-TiO_(2)复合光催化材料。运用SEM、TEM、XRD和TG等表征手段对材料进行表征,结论如下:550℃煅烧时的样品为包含少量碳的高结晶度的锐钛矿相TiO 2,且550℃煅烧时的样品依然保持了完整的核壳结构。此外,C-TiO_(2)复合材料的比表面积高达85.69 m 2·g^(-1),平均孔径为16.4 nm以及孔体积为0.423 m 3·g^(-1)。在UV-Vis光照射下,C-TiO_(2)复合材料分别对罗丹明B(RhB)、亚甲基蓝(MB)和刚果红(CR)3种染料显示出增强的光催化降解活性。展开更多
文摘Polarons are widely considered to play a crucial role in the charge transport and photocatalytic performance of materials,but the mechanisms of their formation and the underlying driving factors remain a matter of controversy.This study delves into the formation of polarons in different crystalline forms of TiO_(2) and their connection with the materials'structure.By employing density functional theory calculations with on-site Coulomb interaction correction(DFT+U),we provide a detailed analysis of the electronic polarization behavior in the anatase and rutile forms of TiO_(2).We focus on the polarization properties of defect-induced and photoexcited excess electrons on various TiO_(2) surfaces.The results reveal that the defect electrons can form small polarons on the anatase TiO_(2)(101)surface,while on the rutile TiO_(2)(110)surface,both small and large polarons(hybrid-state polarons)are formed.Photoexcited electrons are capable of forming both small and large polarons on the surfaces of both crystal types.The analysis indicates that the differences in polaron distribution are primarily determined by the intrinsic properties of the crystals;the structural and symmetry differences between anatase and rutile TiO_(2) lead to the distinct polaron behaviors.Further investigation suggests that the polarization behavior of defect electrons is also related to the arrangement of electron orbitals around the Ti atoms,while the polarization of photoexcited electrons is mainly facilitated by the lattice distortions.These findings elucidate the formation mechanisms of different types of polarons and may contribute to understanding the performance of TiO_(2)in different fields.
文摘In the current research,a thorough examination unfolds concerning the attributes of magnetohydrodynamic(MHD)boundary layer flow and heat transfer inherent to nanoliquids derived from Sisko Al_(2)O_(3)-Eg and TiO_(2)-Eg compositions.Such nanoliquids are subjected to an extending surface.Consideration is duly given to slip boundary conditions,as well as the effects stemming from variable viscosity and variable thermal conductivity.The analytical approach applied involves the application of suitable similarity transformations.These conversions serve to transform the initial set of complex nonlinear partial differential equations into a more manageable assembly of ordinary differential equations.Through the utilization of the FEM,these reformulated equations are solved,considering the specified boundary conditions.The outcomes attained are graphically depicted by means of plots and tables.These visual aids facilitate a comprehensive exploration of how diverse parameters exert influence over the distributions of velocity,temperature,and concentration.Furthermore,detailed scrutiny is directed towards the fluctuations characterizing pivotal parameters,viz.,Nusselt number,skin-friction coefficient,and Sherwood number.It is identified that the Nusselt number showcases a diminishing trend coinciding with increasing values of the volume fraction parameter(φ).This trend remains consistent regardless of whether the nanoliquid under consideration is Al_(2)O_(3)-Eg or TiO_(2)-Eg based.In contrast,both the skin-friction coefficient and Sherwood number assume lower values as the volume fraction parameter(φ)escalates.This pattern remains congruent across both classifications of nanoliquids.The findings of the study impart valuable insights into the complex interplay governing the characteristics of HMT pertaining to Sisko Al_(2)O_(3)-Eg and TiO_(2)-Eg nanoliquids along an extending surface.
文摘化工、纺织印染与农药化肥等产业的蓬勃发展推动着人类社会的进步,但同时也给环境治理带来了巨大难题。目前,光催化降解局限于在特定波长下针对单一有机污染物进行降解,然而现实中的情况往往更复杂。因此,开发一种多功能光催化材料用于光催化降解不同有机污染物显得尤为重要。采用一步无模板溶剂热法合成了核壳结构的C-TiO_(2)复合材料前驱体,并在氩气气氛下煅烧得到高结晶度的C-TiO_(2)复合光催化材料。运用SEM、TEM、XRD和TG等表征手段对材料进行表征,结论如下:550℃煅烧时的样品为包含少量碳的高结晶度的锐钛矿相TiO 2,且550℃煅烧时的样品依然保持了完整的核壳结构。此外,C-TiO_(2)复合材料的比表面积高达85.69 m 2·g^(-1),平均孔径为16.4 nm以及孔体积为0.423 m 3·g^(-1)。在UV-Vis光照射下,C-TiO_(2)复合材料分别对罗丹明B(RhB)、亚甲基蓝(MB)和刚果红(CR)3种染料显示出增强的光催化降解活性。
