Alexander Nechaev

Ionic self-assembly of porphyrin nanostructures on the surface of charge-altered track-etched membranes

Track-etched polymer membranes are typically used as templates in the synthesis of various nanowires or nanotubes arrays. The unique advantages of track-etched membranes, such as uniform pore structure, excellent porosity, easily tailored pore sizes, and a well characterized surface chemistry, may find use in self-assembly strategies where colloidal nanostructures can be tethered to a suitable substrate to produce devices of interest. Meso-tetrakis(4-phenylsulfonicacid)porphyrin dihydrochloride and Sn(IV) tetrakis(4-pyridyl)porphyrin were used to synthesize ionic self-assembled porphyrin nanorods. The track-etched membranes surface charge was changed from negative to positive using polyethyleneimine. The porphyrin nanorods were either filtered through or self-assembled onto the surface of track-etched membranes. Comparisons were made with track-etched membranes modified with, and without, polyethyleneimine. Assembly of the porphyrin nanotubes only occurred on the surface of positively charged track-etched membranes, and filtration of the porphyrin nanorods produced a mesh-like structure on the surface of the membrane irrespective of the track-etched membrane pore diameter. In each case the characteristic absorbance profiles of the porphyrin nanorods was maintained. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and UV-vis spectroscopy were used to characterize the various systems.

Synthesis highly active platinum tri-metallic electrocatalysts using "one-step" organometallic chemical vapour deposition technique for methanol oxidation process

A simple solvent free method for the synthesis of tri-metallic platinum electrocatalysts on carbon nanotubes is presented. By investigating the platinum alloy electrocatalysts, it was showed that the additional metals of platinum alloys could reduce the metal particle sizes and produce larger chemical-active surface area, as well as the higher methanol oxidation activity of the catalysts. The organometallic chemical vapour deposition method was successfully applied to produce multiple samples of PtRuFe, PtRuCu and PtRuV. The electrocatalysts were characterized by ICP, XRD, HRTEM and the catalytic activity was determined by cyclic voltammetry (CV).

COMPOSITE ELECTRODES BASED ON PLATINUM NANOPARTICLES, CARBON NANOTUBES AND NICKEL MICRO-WIRE ARRAYS PRODUCED BY TEMPLATE SYNTHESIS TECHNIQUE

Ion track poly-ethylene-terephthalate membranes (pore diameter 200-, 400-, 1,000-nm), were employed as sacrificial templates for the preparation of micro-wire arrays by the electrodeposition of nickel. After etching of the template, the Ni micro-wire arrays were used as a scaffold for the growth of carbon nanotubes by chemical vapour deposition. The growth of carbon nanotubes on the nickel micro-wire arrays was found to enhance the electrochemically active surface area, redox properties in basic solution, and catalytic activity towards the hydrogen evolution reaction. The subsequent deposition of Pt onto the consolidated composite carbon material by electroless deposition enhanced the catalytic activity of the composite materials further. The significance towards applications as high surface area electrodes, especially for the hydrogen evolution reaction in water electrolysis, is also presented.