为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟...为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟计算。模拟结果表明,4种阳离子CH6N+,C_2H_8N^+,C3H10N+及C4H12N+在高岭石(001)面都能发生稳定吸附,其较为稳定构型的吸附能分别-125.385,-126.154,-128.654和-109.711 k J/mol;但3种胺阳离子与季铵阳离子的吸附机理不同:胺阳离子在高岭石(001)面的吸附是静电引力和氢键的共同作用,季铵阳离子则只通过静电引力作用与高岭石(001)面发生吸附。静电引力作用是导致不同胺/铵阳离子在高岭石(001)发生吸附的主导作用。展开更多
Ultrathin TiO2 nanosheets with coexposed {001}/{101} facets have attracted considerable attention because of their high photocatalytic activity. However, the charge-separated states in the TiO2 nanosheets must be exte...Ultrathin TiO2 nanosheets with coexposed {001}/{101} facets have attracted considerable attention because of their high photocatalytic activity. However, the charge-separated states in the TiO2 nanosheets must be extended to further enhance their photocatalytic activity for H2 evolution. Herein, we present a successful attempt to selectively dope lanthanide ions into the {101} facets of ultrathin TiO2 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 TiO2 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 H2 evolution activity of optimal Yb3+-doped TiO2 nanosheets compared to that of their undoped counterparts. Furthermore, when Pt nanoparticles were used as cocatalysts to reduce the H2 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 H2 evolution activity of lanthanide-doped TiO2 nanosheets with coexposed {001}/{101} facets.展开更多
The collecting power of tertiary amines（DRN,DEN and DPN） on kaolinite follows the order of DENDPNDRN.After reacting with DRN,DEN and DPN,the surface potentials of kaolinite increase remarkably,and the recruitments c...The collecting power of tertiary amines（DRN,DEN and DPN） on kaolinite follows the order of DENDPNDRN.After reacting with DRN,DEN and DPN,the surface potentials of kaolinite increase remarkably,and the recruitments caused by collectors also follow the order of DENDPNDRN.The results of dynamics simulation show that the geometries of substituent groups bonding to N are deflected and twisted,and some of bond angles are changed when tertiary amines cations adsorb on kaolinite（001） surface.Based on the results of dynamics simulations and quantum chemistry calculations,the electrostatic forces between three tertiary amines cations and 4×4×3（001） plane of kaolinite are 1.38×10？7 N（DRN12H＋）,1.44×10-6 N（DEN12H＋）,1.383×10-6 N（DPN12H＋）,respectively.展开更多
{001} facets dominated single crystalline anatase TiO2 nanosheet array （TNSA） was synthe-sized through an optimized organic solvothermal route on uorine-doped tin oxide substrate. The field emission scanning electro...{001} facets dominated single crystalline anatase TiO2 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 TiO2 nanoparticles, which may be attributed to the specific atom structure of reactive {001} facets.展开更多
为研究高岭石(001)面与水分子的相互作用机理,用Material studio 8.0构建了高岭石(001)面的晶体模型,使用GGA-PBE优化高岭石(001)面,分别计算(001)面和含有1、2、4个水分子的分子团吸附构型和平均结合能。结果表明,随着水分子数量的增加...为研究高岭石(001)面与水分子的相互作用机理,用Material studio 8.0构建了高岭石(001)面的晶体模型,使用GGA-PBE优化高岭石(001)面,分别计算(001)面和含有1、2、4个水分子的分子团吸附构型和平均结合能。结果表明,随着水分子数量的增加,结合能绝对值从35.87 kJ/mol增加到53.94 kJ/mol,复合体系稳定性增加。通过静电势分析可知,高岭石表面主要是负静电势区域略大于正静电势区域。当水分子数量由1个增加到4个时,静电势绝对值较大(>188.18 kJ/mol)的面积由7.99%增加到8.49%,整体静电势水平提高,有利于后续水分子吸附。运用RDG函数,展示了高岭石和水分子之间的弱相互作用,结果表明高岭石和水分子主要通过氢键方式结合。由AIM分析的结果可知,高岭石-水的氢键键能弱于水-水的氢键,当水分子数量增加时,高岭石-水氢键键能会进一步减弱。展开更多
文摘为探索阳离子胺盐和季铵盐在高岭石表面的吸附机理,构建了CH6N+(伯胺阳离子)、C_2H_8N^+(仲胺阳离子)、C3H10N+(叔胺阳离子)及C4H12N+(季铵阳离子)4种不同胺/铵阳离子构型,并采用密度泛函理论对4种阳离子在高岭石(001)面的吸附进行模拟计算。模拟结果表明,4种阳离子CH6N+,C_2H_8N^+,C3H10N+及C4H12N+在高岭石(001)面都能发生稳定吸附,其较为稳定构型的吸附能分别-125.385,-126.154,-128.654和-109.711 k J/mol;但3种胺阳离子与季铵阳离子的吸附机理不同:胺阳离子在高岭石(001)面的吸附是静电引力和氢键的共同作用,季铵阳离子则只通过静电引力作用与高岭石(001)面发生吸附。静电引力作用是导致不同胺/铵阳离子在高岭石(001)发生吸附的主导作用。
基金supported by the National Natural Science Foundation of China(51772041,11474046,61775024)the Natural Science Foundation of Liaoning Province(20170540190,201602191)+3 种基金the Program for Liaoning Excellent Talents in University(LNET)(LR2015016,LR2017004)the Program for Dalian Excellent Talents(2016RQ069)the Science and the Technique Foundation of Dalian(2014J11JH134,2015J12JH201)the Fundamental Research Funds for the Central Universities(wd01206)~~
文摘Ultrathin TiO2 nanosheets with coexposed {001}/{101} facets have attracted considerable attention because of their high photocatalytic activity. However, the charge-separated states in the TiO2 nanosheets must be extended to further enhance their photocatalytic activity for H2 evolution. Herein, we present a successful attempt to selectively dope lanthanide ions into the {101} facets of ultrathin TiO2 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 TiO2 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 H2 evolution activity of optimal Yb3+-doped TiO2 nanosheets compared to that of their undoped counterparts. Furthermore, when Pt nanoparticles were used as cocatalysts to reduce the H2 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 H2 evolution activity of lanthanide-doped TiO2 nanosheets with coexposed {001}/{101} facets.
基金Project (2005CB623701) supported by the National Basic Research Program of China Project (201011031) supported by National Department Public Benefit Research Foundation from Ministry of Land and Resources of China+1 种基金 Project (2935) supported by the Foundation for the Author of Zhengzhou Institute of Multipurpose Utilization of Mineral Resources CAGS, China Project (1212011120304) supported by the Geological Surrey Program
文摘The collecting power of tertiary amines（DRN,DEN and DPN） on kaolinite follows the order of DENDPNDRN.After reacting with DRN,DEN and DPN,the surface potentials of kaolinite increase remarkably,and the recruitments caused by collectors also follow the order of DENDPNDRN.The results of dynamics simulation show that the geometries of substituent groups bonding to N are deflected and twisted,and some of bond angles are changed when tertiary amines cations adsorb on kaolinite（001） surface.Based on the results of dynamics simulations and quantum chemistry calculations,the electrostatic forces between three tertiary amines cations and 4×4×3（001） plane of kaolinite are 1.38×10？7 N（DRN12H＋）,1.44×10-6 N（DEN12H＋）,1.383×10-6 N（DPN12H＋）,respectively.
文摘{001} facets dominated single crystalline anatase TiO2 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 TiO2 nanoparticles, which may be attributed to the specific atom structure of reactive {001} facets.
