A Npg-Based Ultra-Thin Anode Catalyst Layer for Spewe

Nanoporous gold (NPG) has a long history of application. By electrochemical or chemical removal of Ag from AgAu alloy, the remaining gold undergoes a self-organization process forming a 3D bicontinuous network with interconnected ligaments. Due to its relatively high surface area, high conductivity, small size ligament and 3D bicontinuous porous structure, NPG has found its way in electrocatalysis, bio-sensors, and fuel cells. By extending dealloy time or thermal coarsening temperature; the structure of NPG can be easily tuned.

In this paper, a facile method was proposed for a novel MEA applied in solid polymer electrolyte water electrolysis (SPEWE). NPG with a thickness of 100 nm dealloyed from 12K gold foil was employed as substrate.  IrO₂ was deposited onto its surface via a conventional thermal decomposition method. A loading of IrO₂ as low as 50 μg cm^-2 was achieved in this experiment while keeping an acceptable performance. With a IrO₂ loading of 0.2 mg cm^-2，the performance was 1.686 V@ 1000 mA cm^-2 at 80 ºC. Scanning electron microscopy measurement showed that IrO₂ formed a uniform thin layer on the surface of NPG. The maximum thickness is 500 nm, which is only 1/20 to the conventional catalyst layer.  The ultra-thin catalyst layer eased the transport of reactant and product, which reasonably explicated the remarkable performance. During the stability test, the cell voltage was constant over 200 h at 250 mA cm^-2. The result here demonstrated that an ultra-thin catalyst layer with a low IrO₂ loading could applied in real solid polymer electrolyte water electrolyzer.