Electrocatalysis and amperometric detection of aliphatic aldehydes at platinum-palladium alloy coated glassy carbon electrode

Aliphatic aldehydes undergo an electrocatalytic oxidation at a platinum-palladium (Pt-Pd) alloy coated glassy carbon electrode. The alloy modification offers a highly sensitive and stable, constant (+0.35 V) potential detection of simple aldehydes. The drastically enhanced catalytic response of the alloy deposit, compared to the single component metals, is attributed to synergistic effect associated with changes in the adsorption features of the surface. The influence of the alloy deposition conditions upon the amperometric response is assessed. Scanning electron microscopy, energy dispersive X-ray analysis and elemental distribution mapping offer useful insights into the microstructure and composition of the alloy deposit. Formaldehyde, acetaldehyde and propionaldehyde were detected in flow-injection analysis at levels as low as 0.9, 6.4 and 6.5 ng (30, 160 and 120 pmol), respectively. Such operation offers lower operating potentials and detection limits compared to the recently developed mixed-valent ruthenium coated detector for aldehydes [2].