Effect of particle size on the performance of plasma-sprayed electrodes for Alkaline Water Electrolysis

Alkaline water electrolysis (AWE) is a technology with the potential of pushing forward the production of green hydrogen towards the implementation of a sustainable hydrogen economy. However, the widespread usage of AWE is limited by its CAPEX/OPEX. Therefore, the development of components with low-cost materials (e.g. noble-metal-free) and low-cost manufacturing processes is a must for the future of green hydrogen production. This contribution shows the development of Raney-type Ni-Al-Mo electrodes for the hydrogen evolution reaction (HER) via atmospheric plasma spraying and confirms the feasibility of using the thermal spraying technique to produce effective electrodes for AWE. Furthermore, by reducing HER overpotential in more than 70mV @ 0.5 A/cm², this study demonstrates that an effective control of processing variables leads the way for increasing electrochemical cell performance. For this, performance optimization through the control of particle size of the feedstock powder is presented. Additionally, this work presents valuable insights regarding the correlation between feedstock’s characteristics and splat formation with the in-situ (as-coated) and ex-situ (Al-Mo leaching process) porosity of Raney-type electrodes and how they impact on the concomitant electrochemical performance. These findings may be crucial for the fabrication of electrodes for AWE and could be extended for other water electrolysis techniques.