[TG-FTIR and XRD spectroscopic analysis for the preparation of nitrogen-doped carbon supported cobalt electrocatalysts].

Nitrogen-doped carbon supported cobalt electrocatalysts for the reduction of oxygen were prepared from the high nitrogen content prepolymer of melamine formaldehyde resin and cobalt acetate. The preparation and structure of the electrocatalysts were investigated by TG-FTIR and XRD spectroscopic analysis methods. The electrochemical reduction of oxygen was studied at the nitrogen-doped carbon supported cobalt by using the rotating disk electrode method. The results indicated that the catalyst structure changed with the carbonization temperature under the protection of the inert gases. Some organic groups were decomposed into CO, CO2, HCHO, NH3 and NO2, which were taken away by the protecting gas. The electrocatalysts exhibited face-centered cubic structure. The RDE results showed that good electrocatalytic activity for oxygen reduction at these electrocatalysts was found under the experimental condition. The onset potential for oxygen reduction (E(onset)) was 0.5 V (vs. SCE). The catalyst prepared under 700 C was found to have the highest activity.

[DRIFTS study of Cu1Zr1Ce9Odelta catalysts for selective CO oxidation].

The Cu1Zr1Ce9Odelta catalysts synthesized with coprecipitation method were used into the selective CO oxidation in hydrogen-rich gas. The adsorbed species and the intermediates on Cu1Zr1Ce9Odelta catalysts were examined by in-situ diffuse reflectance FTIR spectroscopy (in-situ DRIFTS) technique. It was found that hydrogen, oxygen and CO in the feed stream were adsorbed competitively at the same adsorption sites on the surface of Cu1Zr1Ce9Odelta catalysts. The pretreatment with hydrogen caused the deep reduction of Cu+ species to Cu0 species and decreased the capacity of CO adsorption on the catalyst surface. The Cu1Zr1Ce9Odelta catalyst pretreated with oxygen offered more active oxygen species and inhibited the deep reduction of Cu+ species. The helium pretreatment only purified the surface of Cu1Zr1Ce9Odelta catalyst. Two IR bands at 2938.7 and 2843.8 cm(-1) due to bridged formate and bidentate formate species appeared at 180 degrees C. The active oxygen anion of Cu1Zr1Ce9Odelta catalyst could react with CO and produce carbonate species at room temperatures. The carbonate and formate species occupied the adsorption sites and deteriorated the catalytic performance of Cu1Zr1Ce9Odelta. Flushing the Cu1ZnrCe9Odelta catalyst with helium at 300 degrees C, the bidentate formate species on the catalyst surface decomposed to monodentate carbonate species and then further decomposed to CO2, which could release the adsorption sites and restore well the catalytic activity.

[Study on CuO-CeO2 catalysts doped with alkali and alkaline earth metal oxides by in-situ DRIFTS].

CuO-CeO2 series catalysts are the effective catalysts for the selective CO oxidation in hydrogen-rich gas. The adsorption species on the CuO-CeO2 catalysts doped with alkali and alkaline earth metal oxides were investigated with in situ diffuse reflectance FTIR spectroscopy (in-situ DRIFTS) technique. The results showed that a bane at 2 106 cm(-1), due to the carbonyl species, appeared on the CuO-CeO2 catalysts. In the reaction atmosphere, the intensity of this band increased first and then decreased with increasing the temperatures. It was noted that the main active adsorption sites of the CuO-CeO2 catalysts were Cu+ species. At lower temperatures, the carbonyl species were desorbed from the surface of CuO-CeO2 catalysts in the reversible form, while they were desorbed mainly in the irreversible form at the higher temperatures. A sharp peak at 3 660 cm(-1), attributed to the geminal Ce(OH)2 group, was also apparent on the surface of reduced CuO-CeO2 catalyst. The peaks at 1 568, 2 838 and 2 948 cm(-1) were attributed to formate species and the peaks centered at 1 257 and 1 633 cm(-1) were assigned to carbonate species. CO could react with the active hydroxyl species and generate formate species. At higher temperatures, the C-H bond of formate species could break and form carbonate species. These two species would decrease the performance of CuO-CeO2 catalysts at higher temperatures. The stronger IR peaks attributed to CO2 and formate species were observed, moreover there was still a weak IR peak assigned to carbonyl species for Cu1 Li1 Ce9Odelta catalyst when the temperature was above 180 degrees C. It was shown that as the electron donor, the doping of Li2 O on CuO-CeO2 catalyst could contribute to the irreversible desorption of CO at lower temperatures and inhibit the adsorption of H2 on the catalytic surface, and benefit the formation of formate species as well. Although the amounts of CO adsorption on Cu1 Mg1 Ce9 Odelta and Cu1 Ba1 Ce9 Odelta catalysts were much more than other catalysts at lower temperatures, they were mainly desorbed in the reversible form, which had no contribution to the selective CO oxidation.

[UV-Vis, FTIR and XRD spectroscopic analysis for the preparation of Pt/CNTs electrocatalysts].

Carbon nanotubes (CNTs) supported platinum electrocatalyst Pt/CNTs with high dispersion were prepared by a modified ethylene glycol method with sodium dodecyl sulfate (SDS) as the stabilizer. UV-Vis, FTIR and XRD spectroscopic analysis methods were used to study the preparation of the electrocatalysts, and the effect of the SDS addition to the ethylene glycol solution on the structure as well as the electrocatalytic activity of the Pt/CNTs electrocatalysts were also investigated. The results showed that PtCl6(2-) could form a complex compound with SDS, and all PtCl6(2-) were completely reduced by ethylene glycol; oxygen containing groups were produced on the surface of CNTs to facilitate the Pt nanoparticle absorption, and no SDS remained on the electrocatalysts; the Pt/CNTs electrocatalysts exhibited face-centered cubic structure; the particle size of Pt/CNTs-2 catalyst prepared by SDS addition was about 4. 5 nm. The CV test results showed that the Pt/CNTs-2 catalyst showed higher methanol electro-oxidation activity compared with Pt/CNTs-1 prepared by traditional ethylene glycol reduction method.

[Analysis of confined crystalline behaviors of poly(styrene)-poly(ethyleneoxide)-poly(styrene) triblock copolymers by inverse gas chromatography].

The confined crystalline behaviors of the triblock copolymers, poly(styrene)-poly(ethyleneoxide)-poly(styrene) (PS-PEO-PS), were studied by using inverse gas chromatography(IGC) probe technique, including phase-transformation of melting crystalline, crystallinity (Xc), melting temperature(Tm) and melting range of temperature. The effects of the molecule-chain length of linear alkane probes on the results are discussed. Results showed that micro-phase separation of PS-PEO-PS had a greater influence on crystallization of PEO molecule-chain. Crystalline-structure of PS-PEO-PS had interphase formed by some kinds of imperfect PEO crystal and amorphous PS. The molecule-chain length of linear alkane probes had no effect on the determination of melting temperature and melting range of temperature of PS-PEO-PS, but had a greater influence on the determination of crystallinity of PS-PEO-PS and investigation phase-transformation of melting crystalline. Crystallinity of PS-PEO-PS determined by IGC was decreased with the increase of molecule-chain length of linear alkane probes. By suitable shorter molecule-chain length of linear alkane probes, it was truer to reflect the existence of interphase of PS-PEO-PS and multi-phase-transformation of melting crystalline presenting in interphase.