Application of Rare earth metal Pt Alloy for Hydrogen Evolution Reaction Catalysts in Polymer electrolyte membrane water electrolyzer (PEMWE)

Abstract

Platinum is the most active electrocatalyst for the hydrogen evolution reaction (HER) in Polymer electrolyte membrane water electrolyzers (PEMWEs). However, the high price and scarcity of platinum are the one of the major factors preventing the large-scale application of PEMWE. In this work, Pt-Sc, Y, La alloy catalysts on carbon supports were synthesized by an electron beam method which can reduce metals that are difficult to reduce. Nanoparticles of 10 nm or less platinum alloy catalysts are confirmed by XRD and TEM analysis. XRD analysis indicated that Pt alloys and Pt/C were successfully synthesized. Peak shifts were found to be the evidences of the alloys due to lattice parameter changes. Catalytic activities were measured with a PEMWE single cell at 80℃. In MEA fabrication, the anode (commercial IrO2) was coated by the decal method and the cathode (Pt alloy) was coated by a spray method. Pt3La was excluded from the single cell analysis because of its low durability in half-cell analysis. From the half-cell, Pt3La/C showed the highest mass activity but the lowest stability. On the other hand, Pt3Sc/C showed highly improved stability than Pt/C. In the single cell analysis, current density 1mA/cm2 was measured at 2.2V with 2mg/cm2 for anode and 0.5mgPt/cm2 for cathode. As the anode overpotential is dominant, so the effect of the platinum alloy did not appear prominently. However, similar activity and durability were measured by using platinum alloy catalysts, which effectively reduced the amount of platinum loading.