Reactive Spray Deposition Technology for Deposition of Protective Metal Layers on Porous Transport Layers in PEM Water Electrolyzers
Authors: Koni Arkid , Zeng Zhiqiao , Bonville Leonard J. , Bliznakov Stoyan , Maric Radenka 
Published: September 2023

Hydrogen today plays a key role in everyday life. Nearly all of the hydrogen consumed in the United State alone are used for the treatment of metals, processing food, petroleum refining, and fuel for aircraft and vehicles [1]. However, the methods of generating this resource revolves around methane pyrolysis, partial oxidation, coal gasification, and electrolysis [2]. The green option of all these methods is electrolysis, but this process accounts for only 4% of the total hydrogen generated [3]. Within this study, Polymer Electrolyte Membrane Water Electrolyzers (PEMWEs) have been studied as alternative green energy technology for Hydrogen production.
PEMWE technology is known for using a cell with solid polymer electrolytes to conduct protons and separating liquid water into product gases of hydrogen and oxygen [4]. A key component within a PEMWE is the Membrane Electrode Assembly (MEA). Within this MEA, there consists of carbon cloth, catalyst coated membrane (CCM), and a porous transport layer (PTL) [5, 6]. For the purposes of this research, we will focus on the PTL as it plays important roles in the cell since it contributes to charge transfer resistance, mass transport, and interfacial contact resistance. However, the PTL is subjected to the highly oxidative environment and overpotentials from the anode side of the electrolyzer which leads to passivation of surface layers and lowering the life expectancy of the PTL as well as cell performance [6]. To combat this, protective layers are applied to the surface of the PTL to mitigate the formation of titanium oxide layers (TiOx). Most coatings applied are platinum, iridium, or gold through magnetron sputter coating. The limitations of most commercial coatings lie in that only surfaces with a direct line of sight to the source material are coated, leaving much of the PTL exposed to oxidation. To combat this, we will use a technique called Reactive Spray Deposition Technology (RSDT). RSDT is a unique and novel open-to-air vapor-phase deposition method developed at UConn’s Center for Clean Energy Engineering [7]. By controlling parameters within the deposition such as quench flow rate, distance of flame, and propane concentrations; we can control particle size, distribution, and coagulation to the surface of the substrate with our precursor layers [8]. This technique allows for a deposition that penetrates deep into the volume of the PTL and provides layer coatings that cover all surfaces with a layer that is uniform, dense and continuous. These layers are further studied and optimized using Focused Ion Beam, Scanning Electron Microscopy, Inductively Coupled Plasma, and Interfacial Contact Resistance.
References:
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[4] Carmo, M; Fritz D; Mergel J; Stolten D (2013). "A comprehensive review on PEM water electrolysis". International Journal of Hydrogen Energy. 38 (12): 4901–4934. doi:10.1016/j.ijhydene.2013.01.151.
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[8] Liu Chang, RWTH Aachen University 2021Noble metal coated porous transport layers for polymer electrolyte membrane water electrolysis