In-situ growth of PPy/MnOx radical quenching layer for durability enhancement of proton exchange membrane in PEMFCs

Proton exchange membrane fuel cells (PEMFCs), which exhibit low environmental impact and high power density, have attracted considerable interest as clean and efficient energy conversion technology. However, the oxidative degradation of the proton exchange membrane (PEM) by in-situ generated peroxide and hydroxyl free radicals commonly leads to performance losses in PEMFC. To alleviate the chemical attack on PEM, we report an antioxidant approach to growing a polypyrrole/manganese dioxide (PPy/MnOx) radical quenching layer on a highly proton conductive membrane surface. The resulting PEM displays improved durability in PEMFC compared with the pristine membrane, as evidenced by at least 150 h stable discharging performance in an H2/O2 PEMFC at a current density of 200 mA cm−2 at 80 °C and a much slower open circuit voltage (OCV) decay. Moreover, the ex-situ conductivity and in-situ fuel cell test indicate that the porous radical quenching layer has a tiny impact on the fuel cell performance. The resultant H2/O2 PEMFC single cell containing the chemically stable PEM exhibits a promisingly high power density of over 900 mW cm−2 at 80 °C with 100% RH.