The effect of thiourea(TU) on the nickel deposition process was analyzed by means of linear-sweep voltammetry. Raman spectroscopy and infrared reflectance spectroscopy were used to investigate the adsorption of TU and...The effect of thiourea(TU) on the nickel deposition process was analyzed by means of linear-sweep voltammetry. Raman spectroscopy and infrared reflectance spectroscopy were used to investigate the adsorption of TU and the formation of nickel-TU complexes on copper surface. The experimental results indicate that the nucleation and the preceding conversion step are involved in the deposition of nickel on copper electrodes. TU makes the onset nucleation potential negative due to the formation of nickel-TU complexes, which can accelerate the nickel deposition. Moreover, the S atom in the TU molecule adsorbed on copper surface facilitates the coordination of TU to Ni 2+ . Meanwhile, TU might be adsorbed at a flatter orientation if no Ni 2+ is on the surface, while at a perpendicular orientation when Ni 2+ is coadsorbed.展开更多
The efficient chiral Ru 3(CO) 12 systems were prepared in situ from Ru 3(CO) 12 and various chiral diimino-or diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hy...The efficient chiral Ru 3(CO) 12 systems were prepared in situ from Ru 3(CO) 12 and various chiral diimino-or diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu 3(CO) 11]- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru 3 framework.展开更多
Direct electroless nickel plating on n-si(100) wafers in alkaline solutions was demonstrated without any activation procedure in advance,the effect of pH and tem- perature of the solutions on size of metal particles i...Direct electroless nickel plating on n-si(100) wafers in alkaline solutions was demonstrated without any activation procedure in advance,the effect of pH and tem- perature of the solutions on size of metal particles in depos- its was examined,and also the element contents os deposits were analyzed by energy disperse spectroscopy (EDS).The results indicated that the size of metal particles increases with increasing temperature or decreasing pH.The possible mechanism of nickel deposition on n-Si(100) was discussed in terms of semiconductor electrochemistry,and the forma- tion of nickel seed crystal on Si was mainly attributed to the generation of atomic hydrogen by electron capture of water molecule from the semiconductor in alkaline solutions.展开更多
Dispersed Pd nanoparticles (Pdn) have been synthesized by reducing H2PdCl4 with ethanol, and stabilized using poly(vinylpyrrolidone) (PVP). The Pdn is applied to the glassy carbon substrate to form a thin film, and th...Dispersed Pd nanoparticles (Pdn) have been synthesized by reducing H2PdCl4 with ethanol, and stabilized using poly(vinylpyrrolidone) (PVP). The Pdn is applied to the glassy carbon substrate to form a thin film, and then the potential cyclic scanning at 50 mV·s?1 from ?0.25 to 1.25 V was carried out for about 30 min to form the aggregations of Pdn (Pdn ). FTIR spectroscopy of both transmission and re- ag flection modes was employed to study CO adsorption on Pdn and Pdn in both solid|liquid and solid|gas interfaces. It has ag been revealed that CO adsorption on Pdn film yields two IR bands near 1964 and 1906 cm?1, which are assigned to IR absorption of CO bonded on asymmetric and symmetric bridge sites, respectively. In contrast to the IR properties of CO adsorbed on Pdn, only species of CO bonded on asym- metric bridge sites was determined on Pdn , and the direc- ag tion of the IR band near 1963 cm?1 is completely inverted. The full width at half-maximum (FWHM) of the COB band as near 1964 cm?1 is measured to be 14 cm?1 on Pdn film, while it is 24 cm?1 on Pdn film. The results of the present study ag demonstrated that the inverting of the IR band direction is a general phenomenon that is closely related to the interaction between nanoparticles in aggregation of Pdn.展开更多
基金the National Natural Science Foundation of China(No.2 0 0 730 35
文摘The effect of thiourea(TU) on the nickel deposition process was analyzed by means of linear-sweep voltammetry. Raman spectroscopy and infrared reflectance spectroscopy were used to investigate the adsorption of TU and the formation of nickel-TU complexes on copper surface. The experimental results indicate that the nucleation and the preceding conversion step are involved in the deposition of nickel on copper electrodes. TU makes the onset nucleation potential negative due to the formation of nickel-TU complexes, which can accelerate the nickel deposition. Moreover, the S atom in the TU molecule adsorbed on copper surface facilitates the coordination of TU to Ni 2+ . Meanwhile, TU might be adsorbed at a flatter orientation if no Ni 2+ is on the surface, while at a perpendicular orientation when Ni 2+ is coadsorbed.
基金Supported by the National Natural Science Foundation of China(No.2 0 0 730 34,2 0 3730 5 6,2 0 1710 37),Fujian Provinceand Technology Comm ission(No.2 0 0 2 F0 16 ) and Xiamen Science and Technology Com mission(No.35 0 2 Z2 0 0 2 10 4 4 )
文摘The efficient chiral Ru 3(CO) 12 systems were prepared in situ from Ru 3(CO) 12 and various chiral diimino-or diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu 3(CO) 11]- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru 3 framework.
文摘Direct electroless nickel plating on n-si(100) wafers in alkaline solutions was demonstrated without any activation procedure in advance,the effect of pH and tem- perature of the solutions on size of metal particles in depos- its was examined,and also the element contents os deposits were analyzed by energy disperse spectroscopy (EDS).The results indicated that the size of metal particles increases with increasing temperature or decreasing pH.The possible mechanism of nickel deposition on n-Si(100) was discussed in terms of semiconductor electrochemistry,and the forma- tion of nickel seed crystal on Si was mainly attributed to the generation of atomic hydrogen by electron capture of water molecule from the semiconductor in alkaline solutions.
文摘Dispersed Pd nanoparticles (Pdn) have been synthesized by reducing H2PdCl4 with ethanol, and stabilized using poly(vinylpyrrolidone) (PVP). The Pdn is applied to the glassy carbon substrate to form a thin film, and then the potential cyclic scanning at 50 mV·s?1 from ?0.25 to 1.25 V was carried out for about 30 min to form the aggregations of Pdn (Pdn ). FTIR spectroscopy of both transmission and re- ag flection modes was employed to study CO adsorption on Pdn and Pdn in both solid|liquid and solid|gas interfaces. It has ag been revealed that CO adsorption on Pdn film yields two IR bands near 1964 and 1906 cm?1, which are assigned to IR absorption of CO bonded on asymmetric and symmetric bridge sites, respectively. In contrast to the IR properties of CO adsorbed on Pdn, only species of CO bonded on asym- metric bridge sites was determined on Pdn , and the direc- ag tion of the IR band near 1963 cm?1 is completely inverted. The full width at half-maximum (FWHM) of the COB band as near 1964 cm?1 is measured to be 14 cm?1 on Pdn film, while it is 24 cm?1 on Pdn film. The results of the present study ag demonstrated that the inverting of the IR band direction is a general phenomenon that is closely related to the interaction between nanoparticles in aggregation of Pdn.
