Biomedical subjects

Shi-gang Sun

Publications and source records attributed to Shi-gang Sun.

5 recordsLinked to original sources

PubMed2004

[Self-assembly and characterization of Pt nanoparticles by electrochemistry and in-situ FTIR reflection spectroscopy].

Pt nanoparticles (Pt(n)) were prepared by chemical reduction method. The average dimension of Pt(n) is about 2.5 nm in diameter determined from TEM studies. The Pt nanoparticles were then self-assembled on massive Au substrate. The process of self-assembly was investigated with Fe(CN)(4-/3-)(6) for redox probe reaction. The result showed that the dithiol assembled on Au surface is inactive for electron transfer. However after assembly of Pt nanoparticles on the dithiol, the Au/SS-Pt(n) electrode becomes conductive again for electron transfer. The adsorption of CO on the Pt nanoparticles self-assembled on Au substrate in 0.1 mol x L(-1) H2SO4 was studied by using in situ FTIR reflection spectroscopy. IR absorption of linear and bridge bonded CO species was observed around 2030 and 1845 cm(-1) respectively. IR absorption of twin bounded CO adsorbed on the Pt nanoparticles was also observed about 2100 cm(-1). The results illustrated that the IR absorption of CO adsorbed on the Pt nanoparticles has been significantly enhanced. The present study is devoted to revealing the intrinsic properties of self-assembly system of nanoparticles, and is of importance in applications of electrocatalysis as well.

Catalysis↗

PubMed2004

[In situ FTIR reflection spectroscopy of molecule probe studies of enhanced IR adsorbtion and response rate to potential on Pd nanoparticles confined].

Palladium nanoparticles (nm-Pd) were synthesized in the supercages of Y-zeolite via "ship-in-a-bottle". Polyvinyl chloride (PVC) and Nafion were used as bonds respectively to prepare zeolite-modified electrode loading nm-Pd by mixed coat and steped coat. IR optical properties of adsorbed CO (COad) were studied by in situ electrochemical FTIR spectrum on zeolite-modified electrode surface prepared by different bond and coating method. Results display the same enhanced IR absorption of COad and different response rate to potential as well as the ability of electron transfer on PVC and Nafion film. Time-dependent vCOB shift was studied for obtaining the information of response rate to potential and electron transfer ability of PVC and Nafion coating. A larger potential lag on PVC coating electrode and a very small potential lag on Nafion coating film were found, showing that different bond and prepared method affect response rate to potential of zeolite-modified electrode. These findings are significant in understanding special optical performance and the electron transfer mechanism of zeolite-modified electrode.

Electrochemistry↗

PubMed2004

[Solid/liquid interfacial in situ IR microscope and step-scan time-resolved FTIR spectroscopy and applications in studies of nanomaterials].

Electrochemical in situ microscope IR reflection spectroscopy and step-scan time-resolved FTIR reflection spectroscopy were established by using an IR-plan advantage microscope and a Nexus 870 FTIR instrument, and a home-made signal synchronizer that harmonizes electrode polarization potential and step-scan spectral data collection sequence. These new techniques have been applied in studies of particular IR properties of 2-dimensional nanomaterials. By applying a treatment of fast potential cycling with different time (tau), a set of nanostructured Pt microelectrodes were prepared. CO adsorption was employed as a probe reaction together with in situ developed microscope FTIR spectroscopy. The results illustrated the variation of abnormal IR features with the nanostructure and the thickness (i.e., the size) of film formed on Pt microelectrode, i.e., following the increase of tau in fast potential cycling treatment, the direction of CO band was turned from absorption to antiabsorption direction, and the intensity and the width of CO band were increased. By taking the advantage of the abnormal infrared effects of nanostructured Pt microelectrode, the sensitivity of in situ IR reflection spectroscopy has been significantly improved, and spectra of time-resolution as fast as 50 micros have been recorded at solid/liquid interfaces. The current studies demonstrated not only the success of development of new techniques of in situ IR spectroscopy, but also the exploitation of the established techniques in studies of nanomaterials.

English Abstract↗

PubMed2003

[In situ FTIR spectroscopy studies of HCOOH oxidation on surface alloy electrocatalysts].

Electrocatalytic properties of three electrodes for formic acid oxidation were studied by using electrochemical in situ FTIR spectroscopy and cyclic voltammetry in this paper. It is demonstrated that the electrocatalytical mechanism of formic acid oxidation on platinum-dispersed carbon(Pt/GC) is similar to that on massive platinum, which involves two paths, i.e. one way through active intermediate and the other through poison intermediate to CO2. The Pt/GC exhibits higher catalytivity than pure platinum. The electrode of Pt/GC modified by Sb (Sb-Pt/GC) was also prepared in the work. It was observed that the onset potential (Ei) for formic acid oxidation on Sb-Pt/GC was shift negatively for 0.20 V. The peak potential (Ep) was observed to shifted negatively to 0.34 V and the value of oxidation current (jp) was enhanced nearly 7.28 times. Similar results were also observed on surface alloy/GC prepared. In this case, Ei and Ep were -0.12 and 0.32 V, respectively, jp was enhanced about 8.15 times, and FWHM (full width at half maximum) was 0.50 V. It is indicated that Sb-Pt/GC and surface alloy/GC can not only effectively restrain the formation of poison intermediate CO, but also significantly increase the electrocatalytic activities for oxidation of active intermediates.

Adsorption↗

PubMed2002

[Spectral analysis in nanometer material science].

Spectral analysis is an important means in studies of nanometer scale systems, and is essential for deep understanding the structure and properties of nanometer materials. This paper reviews the recent progresses made in studies of nanometer materials using spectral analysis methods such as UV-Visible spectroscopy, FTIR spectroscopy, Raman spectroscopy, Mössbauer spectroscopy, positron annihilation and photoacoustic spectroscopy. The principle, characteristics and applications of most frequently employed spectral methods are introduced briefly and illustrated with typical examples. Future perspectives of spectral analysis in nanometer field are discussed. New directions of establishing spectral analysis methods at nanometer scale resolution and developing new spectroscopy technology in nanometer material studies are also emphasized.

Nanotechnology↗