Photochemical reduction of graphene oxide in colloidal solution

Stable aqueous colloidal solutions of graphene oxide stabilized with sodium polyphosphate were obtained. During irradiation of the colloids the oxygen-containing groups of the graphene oxide are eliminated, and the aromatic graphite-like regions in its composition are expanded. This is accompanied by decrease in the energy of the electronic transitions E_bg in such sp2-hybridized fragments. Photoreduction of the colloidal particles of graphene oxide leads to changes in their hydrodynamic size, resulting from 𝜋𝜋 interactions between the aromatic fragments in the particles. It was shown that the E_bg value can be varied purposefully in the range of 0.5-1.9 eV by varying the experimental conditions.     

Investigation of the photoelectrophysical and spectral characteristics of the heterostructure of cadmium telluride — An electrically conducting poly(N-epoxypropylcarbazole)

On the basis of the study of the photoelectrophysical and spectral characteristics of the heterostructure of cadmium telluride — an electrically conducting poly (N-epoxypropylcarbazole) — the possibility of using this heterotransition as a solid-state photogalvanic cell with efficiency of luminous-to-electrical-energy conversion efficiency equal to 3.2% and possessing spectral sensitivity in the UV, visible, and near IR regions was demonstrated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 29, No. 2, pp. 138–142, March–April, 1993.The authors would like to express gratitude to Ya. I. Vartsemakhe for aid in recording the spectral dependence of the photo-emf of the heterostructure and T. A. Vardapetyan for kindly providhg the polycrystalline CdTe.The work is being financed by the State Committee of the Ukraine on problems on science and technology within the framework of the State Scientific and Technical Program of the Ukraine: New Substances and Materials.     

Effect of various factors on the electro-chemically activated insertion of carbon dioxide into acyl chlorides

The effect of the electronic structure of the reagents, the nature of the supporting electrolyte, the electrode material, the electrolysis conditions, and other factors on the electrochemical carboxylation of acyl chlorides (CH₃COCl, p-X-C₆H₄COCl, where X=CH₃, H, NO₂) and on the yields of the respective α-oxocarboxylic acids were studied. It was shown that factors that accelerate the cathodic reduction of the acid chlorides and stabilize the intermediates and products of the electrosynthesis lead to an increase in the yield of the oxo acids. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Nauki Prosp., Kiev 252039. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 1, pp. 1–5, January–February, 1998.     

Effect of the Dopant Nature on the Response of Sensor Arrays Based on Polypyrrole

The effect of the nature of the dopant on the response of a sensor array based on films of polypyrrole under the influence of the vapor of various organic solvents was studied. It was found the electric conductivity of the polymer can both increase and decrease during the action of analytes on electropolymerized films of polypyrrole. It is suggested that the main factors determining the response of polypyrrole are the morphology of the films and the type of charge carriers in the polymer, which depend on the nature of the dopant anion, and also the polarity and nucleophilicity/electrophilicity of the analyte. The responses of polypyrrole and polyaniline are compared, and the effect of the nature of the conducting polymer on them is analyzed. __________ Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 265–271, September–October, 2005.