Pt-Pd Nanoparticles from Green Synthesis Combined with Multi-walled Carbon Nano-tubes as a Modifying Layer on a Glassy Carbon Electrode for the Electrochemical Detection of Pyrene

A glassy carbon electrode was modified with Pt-Pd nanoparticles (NPs) and multi-walled carbon nanotubes (MWCNTs) for electrochemical detection of pyrene, a polycyclic aromatic hydrocarbon suggested by environmental authorities for monitoring. The Pt-Pd NPs were synthesized using metal salt precursors and an aqueous extract of E. grandis leaves. This offered an alternative synthesis route that eliminates use of the conventional hazardous reductive chemicals. The size of the NPs was optimized by varying the proportions of the Pt and Pd ions in the precursor solutions. Square wave voltammetry and cyclic voltammetry were used in the electrochemical analysis of pyrene. The electrode modification resulted in an increase of the peak current for pyrene oxidation by up to 200 %. The electrochemical process was determined to be both adsorption- and diffusion-controlled making it necessary to have a pre-concentration time before analysis. The linear range of analysis for the electrochemical sensor was 66–130 µM with R2 of 0.99516. The lower limit of detection was determined to be 23 µM. Pt-Pd NPs from a green process could be used together with MWCNTs to modify an electrode for relatively sensitive electrochemical detection of pyrene. An increase in the separation between the oxidation peaks of pyrene and anthracene at the modified electrode provides a slight improvement in selectivity.