Layer-by-layer self assembly of a water-soluble phthalocyanine on gold. Application to the electrochemical determination of hydrogen peroxide

A self-assembled molecular film of a water-soluble cobalt tetrasulfophthalocyanine was deposited on a gold substrate premodified with poly(diallyldimethylammonium chloride). The process of layer-by-layer assembly on the gold substrate was characterized using UV-Vis, Raman spectroscopy, ellipsometry, contact angle measurements, atomic force microscopy and electrochemical methods. Results demonstrate the formation of a completely covered phthalocyanine film on the gold surface. UV-Vis spectra indicated the formation of monolayer film of the phthalocyanine on the surface. The functionalized surface is uniformly covered and becomes hydrophilic after modification. The modified gold surface exhibits a reversible redox behavior and acts as an electronic conductor for the electrochemical reduction of hydrogen peroxide in pH 7.0 phosphate buffer. A linear increase in the catalytic current is observed for the reduction of hydrogen peroxide in the concentration range from 1 to 20 μM, with a detection limit of 0.4 μM. Hydrogen peroxide spiked pond water sample showed a recovery of 94% indicating the method is selective and can be applied for various applications. The present method is a simple, cost effective and sensitive electrochemical method for the detection and quantification of hydrogen peroxide.

LBL assembly of water-soluble phthalocyanine has been prepared and characterized with UV-Vis, Raman, AFM, contact angle and electrochemistry. The phthalocyanine film is a good electrocatalyst for the reduction of hydrogen peroxide.Figure optionsDownload as PowerPoint slideHighlights
► Layer-by-layer assembly of compact monolayer of water soluble phthalocyanine on gold surface.
► Modified surface becomes more hydrophilic in nature.
► Catalyses H2O2 in the concentration range 1-20 μM; detection limit 0.4 μM with a recovery of 94% for spiked sample.
► Modified electrode is easy to prepare, handle, stable, robust and compatible for biorelated application.