PLATINUM DISSOLUTION IN PROTON EXCHANGE MEMBRANE FUEL CELL UNDER MECHANICAL VIBRATIONS

摘要

One of the factors that affect the performance of proton exchange membrane fuel cells (PEMFC) is the loss of electrochemically active surface area of the Platinum (Pt) based electrocatalyst due to platinum dissolution and sintering. The intent of the current research is to understand the effect of mechanical vibrations on the Pt particles dissolution and overall PEMFC performance. This study is of great importance for the automotive application of fuel cells, since they operate under a vibrating environment. Carbon supported platinum plays an important role as an electrocatalyst in PEMFC. Pt particles, typically a few nanometers in size, are distributed on both cathode and anode sides. Pt particle dissolution and sintering is accelerated by a number of factors, one of which is potential cycling during fuel cell operation. To study the effect of mechanical vibrations on Pt dissolution and sintering, an electrocatalyst (from cathode side) was analyzed by SEM/EDS (Energy Dispersive Spectroscopy). The performance, dissolution and sintering of the Pt particles of 25 cm~2 electrocatalyst coated membrane were studied during a series of tests. The experiment was conducted by running three accelerated tests. Each test duration was 300 hours, with different parameters of oscillations: one test without vibrations and remaining two tests under vibrations with frequencies of 20 Hz and 50 Hz (5g of magnitude) respectively. For each of the three tests a pristine membrane was used. The catalyst of each membrane was analyzed by ESEM/EDS in pristine state and in degraded state (after 300 hours of accelerated test). In order to specify the same area of observation on a catalyst before and after accelerated test, a relocation technique was used.