High-performance porous 3D Ni skeleton electrodes for the oxygen evolution reaction

Abstract

A key component of green hydrogen production technologies is the fabrication of large-scale porous transport layer (PTL) for use in anion electrolyte membrane water electrolysers (AEMWEs). One strategy to achieve that goal is to manufacture Ni-based 3D electrode skeletons that can be further catalyzed to achieve high current densities at low overpotentials. In the present work, shock-wave induced spray (SWIS) and cold spray (CS) deposition techniques were used to prepare 20 cm2 Ni-based electrode skeletons. In our experimental conditions, the porosity of coatings prepared using the SWIS deposition system and Ni powders with particle sizes D50 = 32 and 75 μm never exceeded 28%. Higher porosity could only be achieved using the CS deposition system and a spheroidal Ni–Al powder, whose particles consist of an aluminum core encapsulated in a nickel shell. After Al leaching in an alkaline solution, the resulting electrodes showed good mechanical and structural integrity with up to 41% porosity. The electrochemical active surface area of the most porous electrodes is a factor of 2100 larger than a polished Ni plate, and it has superaerophobic properties with a captive air bubble contact angle of 151°. During 1 h of electrolysis, the overpotential at 100 mA cm−2 of the most active leached Ni–Al cold spray deposited electrode was 330 mV, compared to 380 mV for a Ni foam electrode.

Keywords

• Water splitting
• Oxygen evolution electrocatalyst
• Large-scale skeleton electrode
• Cold spray
• Shock-wave induced spray
• Leaching