Poly(methylhydrosiloxane)was modified with methylmethacrylate by the hydrosilylation reaction,using Pt as the catalyst.The reaction was operated at the high temperature(about 140℃).
Rh/SiO2 catalysts with tethered-phosphines with different alkyl spacer lengths have been prepared,tested and characterized.Lengthening the alkyl spacer of the tethered-phosphine improved the flexibility of tethered-ph...Rh/SiO2 catalysts with tethered-phosphines with different alkyl spacer lengths have been prepared,tested and characterized.Lengthening the alkyl spacer of the tethered-phosphine improved the flexibility of tethered-phospine,promoted the formation of active species and enhanced the activity of hydroformylation over other tethered-phosphine modified Rh/SiO2 catalysts.展开更多
A combination of X-ray powder diffraction, thermogravimetric analysis, diffuse reflection infrared Fourier transform, and ^31p magic-angle spinning nuclear magnetic resonance techniques with density function computati...A combination of X-ray powder diffraction, thermogravimetric analysis, diffuse reflection infrared Fourier transform, and ^31p magic-angle spinning nuclear magnetic resonance techniques with density function computation was used to elucidate the products and mecha- nism of the reactions among silica, H3PO4, and NaH2PO4 during the preparation of silica supported H3PO4 and NaH2PO4 catalysts. The spectral test results indicate that besides polyphosphoric acid, silicon phosphates on silica supported H3PO4 are also formed. On silica supported NaH2PO4 only sodium polyphosphates are present. Density functional theory （DFT） simulations indicate that in the initial stage, reaction of H3PO4 with silanol groups on the silica support is more favorable than that between H3PO4 itself. In contrast, dimerization and trimerization of NaH2PO4 are predicted to be the predominant initial reactions for the silica supported NaH2PO4 catalyst.展开更多
The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as S...The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as SnO2 and SnO2/ZnO bi-layer films were exposed to atomic H at various substrate temperatures and for various treatment times. A decrease in the transmittance due to reduction by atomic H was scarcely observed for SnO2 / ZnO bi-layer,while a decrease for SnO2 was found to depend strongly on the substrate temperature. The resistivity of SnO2 films decreases significantly when substrate temperature exceeds 150℃in H-plasma. However, H-plasma treatment has little impact on the resistivity of SnO2/ZnO bi-layer film. The reason for the decrease in the transmittance is the appearance of metallic Sn on the surface, and under this condition no μc-Si： H film is deposited. SnO2/ZnO bi-layer is very effective for the suppression of the reduction of TCO during μc-Si：H deposition. The performance of microcrystalline silicon solar cells fabricated on ZnO/SnO2/glass is also investigated.展开更多
The solution of H 2O 2 is proposed to post-treat thick porous silicon (PS) films.The prepared PS film as the cathode is applied about 10mA/cm 2 current in mixture of ethanol,HF,and H 2O 2 solutions,which is expec...The solution of H 2O 2 is proposed to post-treat thick porous silicon (PS) films.The prepared PS film as the cathode is applied about 10mA/cm 2 current in mixture of ethanol,HF,and H 2O 2 solutions,which is expected to improve the stability and the smoothness of the surface and the mechanical property of the thick porous silicon films.The microstructure of the PS thick films with thicknesse of 20μm and 70μm has been studied.The SEM images show significant improved smoothness on surface of PS films,and XRD spectra suggest the formation of oxide layer after post-treating in H 2O 2.展开更多
基金Project supported by the National Natural Science Foundation of China(No.21772171)the National Basic Research Program of China(973 Program,No.2015CB856600)+1 种基金the Zhejiang Provincial Natural Science Foundation(No.LR19B020001)the K.P.Chao’s High Technology Development Foundation of Zhejiang University and the Fundamental Research Funds for the Central Universities~~
文摘Poly(methylhydrosiloxane)was modified with methylmethacrylate by the hydrosilylation reaction,using Pt as the catalyst.The reaction was operated at the high temperature(about 140℃).
基金financially supported by the National Natural Science Foundation of China(21273227,20903090)~~
文摘Rh/SiO2 catalysts with tethered-phosphines with different alkyl spacer lengths have been prepared,tested and characterized.Lengthening the alkyl spacer of the tethered-phosphine improved the flexibility of tethered-phospine,promoted the formation of active species and enhanced the activity of hydroformylation over other tethered-phosphine modified Rh/SiO2 catalysts.
文摘A combination of X-ray powder diffraction, thermogravimetric analysis, diffuse reflection infrared Fourier transform, and ^31p magic-angle spinning nuclear magnetic resonance techniques with density function computation was used to elucidate the products and mecha- nism of the reactions among silica, H3PO4, and NaH2PO4 during the preparation of silica supported H3PO4 and NaH2PO4 catalysts. The spectral test results indicate that besides polyphosphoric acid, silicon phosphates on silica supported H3PO4 are also formed. On silica supported NaH2PO4 only sodium polyphosphates are present. Density functional theory （DFT） simulations indicate that in the initial stage, reaction of H3PO4 with silanol groups on the silica support is more favorable than that between H3PO4 itself. In contrast, dimerization and trimerization of NaH2PO4 are predicted to be the predominant initial reactions for the silica supported NaH2PO4 catalyst.
文摘The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as SnO2 and SnO2/ZnO bi-layer films were exposed to atomic H at various substrate temperatures and for various treatment times. A decrease in the transmittance due to reduction by atomic H was scarcely observed for SnO2 / ZnO bi-layer,while a decrease for SnO2 was found to depend strongly on the substrate temperature. The resistivity of SnO2 films decreases significantly when substrate temperature exceeds 150℃in H-plasma. However, H-plasma treatment has little impact on the resistivity of SnO2/ZnO bi-layer film. The reason for the decrease in the transmittance is the appearance of metallic Sn on the surface, and under this condition no μc-Si： H film is deposited. SnO2/ZnO bi-layer is very effective for the suppression of the reduction of TCO during μc-Si：H deposition. The performance of microcrystalline silicon solar cells fabricated on ZnO/SnO2/glass is also investigated.
文摘The solution of H 2O 2 is proposed to post-treat thick porous silicon (PS) films.The prepared PS film as the cathode is applied about 10mA/cm 2 current in mixture of ethanol,HF,and H 2O 2 solutions,which is expected to improve the stability and the smoothness of the surface and the mechanical property of the thick porous silicon films.The microstructure of the PS thick films with thicknesse of 20μm and 70μm has been studied.The SEM images show significant improved smoothness on surface of PS films,and XRD spectra suggest the formation of oxide layer after post-treating in H 2O 2.
