H2 quantification based on selective pre-concentration and oxidative stripping at Pd modified microelectrodes

A concept for amperometric detection and quantification of H2 employing a palladium microsensor is demonstrated. Resistive sensors exploit the outstanding affinity of Pd toward H2 absorption leading to a detectable modulation in resistivity, while amperometric sensors are generally non-Pd-based and detect the electrochemical oxidation of H2 at the electrode surface. The latter method requires the use of a porous membrane in order to ensure that the electrode reaction is limited by the diffusion of H2 from the gas phase to the sensing electrode. We introduce direct quantification of dissolved H2 in aqueous electrolytes that relies on a pre-concentration mechanism at Pd modified microelectrodes and the subsequent amperometric or coulometric oxidation of H2 from bulk Pd. Due to the straightforward data analysis, this method allows for precise determination of H2 concentration in solution, with the maximum sensitivity obtained by adjusting the pre-concentration time.