Ultra-thin platinum catalytic electrodes fabricated by atomic layer deposition

Abstract

Because noble metal catalysts (e.g. Pt) are one of the main contributors to low-temperature (<500 °C) fuel cell costs, significant efforts have been made to lower the noble metal loading in constructing fuel cell electrodes. In this work, ultra-thin (∼10 nm) platinum (Pt) cathode/catalyst layers were patterned by atomic layer deposition (ALD) and tested as catalytic electrodes (cathode) for low-temperature solid oxide fuel cells. We found that 180 cycles or approximately 10 nm of ALD Pt, with a Pt loading of only 0.02 mg cm⁻², were sufficient for the purpose of a catalytic cathode. Furthermore, this ALD Pt resulted in fuel cell performance comparable to that achieved by 80 nm-thick sputtered Pt. Transmission electron microscope (TEM) observations revealed the optimized number of ALD cycles of Pt for the catalytic electrode, which renders both contiguity and high triple-phase boundary (TPB) density. This result suggests the ability to significantly reduce Pt loading, thereby reducing the cost, and furthermore, can be easily applied to high performance fuel cells with complex 3-D structures.