Design Focus\nof Anodes toward High-Current-Density\nLow-Pt-Loading\nProton Exchange Membrane Fuel Cells

Based on the demand of low total Pt loading and high\ncurrent density\nfor proton exchange membrane fuel cells, it is necessary to further\nlessen the anode Pt loading to reserve enough space for the cathode.\nIn terms of high current density, the anode must facilitate the rapid\noxidation of hydrogen to generate protons while ensuring rapid proton\nconduct. Proton conduct is highly related to the water content of\nthe catalyst layer. Therefore, in this work, the effects of anode\ndesign with low Pt loading under high current density was studied\nin depth via comparing the single cell performance, electrochemical\nH<sub>2</sub>-pumping test, electrochemical impedance spectroscopy,\nand analysis of distribution of relaxation times. It is found that\nthe hydrogen oxidation reaction activation overpotential does not\nsignificantly deteriorate even at an anode Pt loading of 0.01 mg<sub>Pt</sub>/cm<sup>2</sup>. However, the thickness of the anode catalyst\nlayer, namely, the water retention capability, has a great impact\non proton conduction resistance under high current density operating\nconditions.