Improvement of proton exchange membrane fuel cells performance by coating hygroscopic zinc oxide on the anodic catalyst layer

This study proposes that hygroscopic zinc oxide (ZnO) nanoparticles, added to the anodic catalyst layer as a water adsorbent by using sputtering deposition, improves the hydration of the anode under dehydrated conditions, thereby enhancing the performance of proton exchange membrane fuel cells (PEMFCs). Scanning electron microscopy analysis indicates that the size of the ZnO nanoparticles ranges between 5 nm and 20 nm on the Si-substrate and aggregates on the platinum/carbon (PtC) catalyst layer with ZnO. The ZnO content of the ZnO/PtC catalyst is estimated by inductively coupled plasma-atomic emission spectra. Water contact angle analyzes show the hydrophilicity of the ZnO/PtC catalyst. Single cell performance with various amounts of ZnO nanoparticles in the anode catalyst layer is investigated at the anode humidifier temperatures of 25 °C, 45 °C, and 65 °C. The cell and cathode humidifier temperatures are fixed at 60 °C and 65 °C, respectively. The membrane-electrode assembly (MEA30) with 0.45 wt.% ZnO in the anode catalyst layer revealed the best performance at anode humidifier temperatures 45 °C and 65 °C, with power densities 43.91% and 25.80% higher than those without ZnO, respectively. The results show that anode catalysts with proper hygroscopic ZnO nanoparticles are ideal for PEMFCs applications.