Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

Abstract

This promising method allows not only to decarbonize the current hydrogen production but to decarbonize other industries as well since the carbon-free electrolytic hydrogen (or derivatives) can replace fossil fuels in the transport and heating sectors as well. As a consequence, the International Energy Agency estimates a 140% growth in hydrogen demand by 2030, with water electrolysis being responsible for almost 40% of the total production. [1] There are three main water electrolysis technologies. The most mature one is alkaline water electrolysis (AWE), with a market share of ≈60%, followed by proton exchange membrane water electrolysis (≈30% market share), and solid oxide water electrolysis. [1,2] Besides being the most mature method, AWE also has the lowest capital cost (€/kW) at a given power input, [3] since it uses abundant and inexpensive materials. [4] The state-of-the-art AWE cell configuration is a zero-gap assembly. In this configuration, the electrodes, in general 2D electrodes such as perforated plates, expanded metals, or meshes, are pressed against a separator with a thickness on the order of hundreds of micrometers. [5] Recently, 3D electrode geometries such as foams and felts have been used with promising results, [6] especially when a forced electrolytic flow is imposed. [7] However, due to the stochastic nature of these geometries, gas removal may not be optimal. As an example, Kou et al. observed an enhancement in gas evacuation when replacing foams with periodic 3D structures. [8] An important method to build tailored 3D periodic metallic structures is additive manufacturing using laser beam melting (LBM), also known as selective laser melting (SLM). [9] In this process, a thin layer of powder is deposited over a substrate plate or on the previously deposited layer and a laser beam melts the powder particles selectively. To avoid oxygen contamination, the process is done in a closed chamber containing an inert gas. [10] With the almost unlimited possible geometries that it allows to fabricate, it is important to find generic guidelines as to what kind of structure presents the best electrolytic performance in view of enhanced gas removal.Recently, a study of membrane distillation for desalination has successfully shown that 3D printed spacers can enhance heat and mass transfer and reduce the formation of dead zones. [11] A zero-gap cell with porous electrodes is a promising configuration for alkaline water electrolysis. However, gas evacuation becomes a challenge in that case, as bubbles can get trapped within the electrode's 3D structure. This work considers a number of 3D printed electrode geometries with so-called triply periodic minimal surfaces (TPMS). The latter is a mathematically defined structure that repeats itself in three dimensions with zero mean curvature, and can therefore be expected to be particularly well-suited to enhance gas evacuation. Another advantage as compared to other state-of-the-art 3D electrodes like foams or felts lies in the fact that their porosity, which dete...

Rational Design of Hydrogen Evolution Reaction Electrocatalysts for Commercial Alkaline Water Electrolysis

“…In this configuration, the irregular geometry of the 3D electrode is often not conducive to bubble removal, which severely limits the use of catalytic sites and the stability of the electrode. [ 170 ] Therefore, the development of suitable electrode substrates and optimization of the electrolyzer structure configuration will be key to promoting further development of alkaline water electrolysis for hydrogen production.…”

“…[166][167][168][169] This is an effective way to solve the bubble mass transfer problem. [170] For example, Li et al prepared Ni electrodes with periodic pore structures based on 3D printing technology. [171] As shown in Figure 12a, in the disordered structure of ordinary Ni foam, the bubble will encounter the force of different pore sizes and zigzag paths, which counteracts the effect of bubble buoyancy and thus affects the migration.…”

Constructing a 1T-MoS2/Ni3S4heterostructure to balance water dissociation and hydroxyl desorption for efficient hydrogen evolution

“…The production of hydrogen through water electrolysis [1][2][3] has long been pursued as a solution to reducing pollution and the scarcity of fossil fuel energy. 4,5 The design of efficient catalysts to reduce electrical energy consumption is a critical aspect of water electrolysis engineering.…”

“…When the HER and OER take place in the same electrolyte, 8,9 the energy required for pH induction and ion exchange is significantly reduced. Alkaline electrolytic water 2,10,11 has advantages for overall water electrolysis 8,12,13 because alkaline conditions are less corrosive for equipment, 3,14 and the OER with a bigger overpotential than the HER prefers to occur in alkaline solutions. 1,15,16 However, most HER catalysts only perform well in acidic electrolytes and would be severely limited in alkaline solutions, with activity several orders of magnitude lower.…”

Highly Efficient All-3D-Printed Electrolyzer toward Ultrastable Water Electrolysis

“…As a consequence, lateral mixing may promote the coalescence of bubbles. For this case, a structure such as a gyroid able to channel the flow is preferred . Therefore, the continuous gas generation reaction efficiency can be guaranteed in the scenario of a real industrial production process.…”