ELECTROCATALYTIC REDUCTION OF HYDROGEN-PEROXIDE ON A PALLADIUM-MODIFIED CARBON-PASTE ELECTRODE

A palladium-dispersed carbon paste electrode was used for the electroc atalytic reduction of hydrogen peroxide. After cycling the potential b etween 0.4 and -0.8V (vs. SCE) in pure dilute alkaline solution (10(-3 ) M NaOH), the resulting electrode surface exhibited stable and sensit ive electrocatalytic response for hydrogen peroxide. The involved cata lytic mechanism was thoroughly investigated. The electrocatalytic effe ct was attributed to electrogenerated elemental palladium at the elect rode surface. The catalytic reduction of hydrogen peroxide proceeds vi a the hydroxyl radical, OH.. Dissolved oxygen can also be catalyticall y reduced in a similar way to hydrogen peroxide. The height of the cat hodic catalytic current peak, as obtained by linear sweep voltammetry (LSV) was directly proportional to the hydrogen peroxide concentration over a very wide concentration range (0.1-600 mg L(-1)). The detectio n limit (3 sigma) was calculated as 50 mu gL(-1) H2O2.