In operando measurement of localised cathode potential to mitigate DMFC temporary degradation

Abstract

An innovative external reference electrode technique has been applied to the cathode of an operating DMFC in order to identify variations in electrode potential across the active area of the cell. The evolution of cathode potential at two different locations in the cell was monitored during operation, with the primary focus on studying the potential dynamics during the temporary degradation recovery procedure, the so-called refresh cycle. The results highlight for the first time a non-uniform local recovery of temporary degradation at the cathode during refresh cycles, associated with varying rates of platinum oxide reduction across the cell, which could lead to current density redistribution and contribute to an uneven degradation of the components. The technique shows great promise for the improvement of long term DMFC performance via optimisation of refresh cycle protocols.