Implementation of Proton Exchange Membrane Water Electrolyzer with Ultralow Pt Loading Cathode through Pt Particle Size Control

Proton exchange membrane water electrolysis is a promising technology for hydrogen production. However, the high-cost catalyst material used in the cathode, particularly Pt, remains a challenge for its commercialization. Therefore, efforts are being made to develop alternative transition-metal or Pt-based alloy catalysts with a reduced Pt loading. In this study, we synthesized Pt catalysts using a Pt-aniline complex and a carbon nanofiber support and controlled the relative abundance of Pt particles according to three defined size categories: particles smaller than 1 nm, particles between 1 and 2 nm, and particles larger than 2 nm. The activity and stability of these catalysts were evaluated in the half- and unit-cell stages. The Pt catalyst, mainly composed of Pt nanoclusters with sizes of 1–2 nm, exhibited high activity and stability. In a unit-cell evaluation, it demonstrated a cell voltage of 1.71 V at 1 A cm–2 with a Pt loading of only 0.015 mgPt cm–2, indicating its potential as an ultralow Pt-loading proton exchange membrane water electrolyzer.