Evaluation of the influence of the catalyst layer composition on the performance of the alkaline water electrolysis utilizing catalyst coated membrane based electrode membrane assembly

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F19%3A43918459" target="_blank" >RIV/60461373:22310/19:43918459 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Evaluation of the influence of the catalyst layer composition on the performance of the alkaline water electrolysis utilizing catalyst coated membrane based electrode membrane assembly

Popis výsledku v původním jazyce

Alkaline water electrolysis represents promising technology for production of the green hydrogen. Advantages of the alkaline water electrolysis over the competitive technologies, such as polymer electrolyte membrane (PEM) or high temperature water electrolysis are several. Between main of them belongs: (i) it is a technology well established in industry, (ii) it does not require precious Pt group metals and (iii) availability of the construction materials. On the other hand, this technology does not achieve intensity and flexibility of the operation comparable to the PEM water electrolysis. This is due to the absence of the membrane based on anion selective polymer material able to ensure sufficient ionic contact between the electrodes and separation of produced gasses at the same time. Utilization of the anion selective polymer electrolyte membrane would allow not only to use zero gap arrangement, but even to deposit electrocatalytic layer directly on the surface of the membrane. Anion selective polymer binder has two vital roles. Firstly, it has to ensure the mechanical stability of the catalyst layer under the conditions of the rapid gas evolution. The second role is to ensure the ionic contact between the catalyst particles, especially in the environment of the diluted alkaline solutions or even demineralized water. Obviously, both can be met with high content of the polymer anion selective membrane in the layer. On the other hand, higher content of the anion selective polymer binder decreases the electronic contact between the catalyst particles which will results in the decrease of the performance of the alkaline water electrolysis. Proper composition of the catalyst layer thus represents critical issue. In this work, we study CCMs with various compositions of the catalyst layer. Air brush spraying at elevated temperature (50 °C) was chosen as a preparation method. The NiCo2O4 and NiFe2O4 were used as anode and cathode catalysts respectively at load 2,5 mg cm-2 which resulted in the thickness of the catalyst layer approximately 30 µm. Block copolymer polystyrene-ethylene-butylene-styrene (PSEBS) with 1,4-diazabicyclo[2.2.2]octane (DABCO) functional groups was used as the membrane and polymer binder of the catalyst layer. Performance of the alkaline water electrolysis in the form of the load curves was measured for all prepared samples with different potassium hydroxide concentrations (1, 5, 10 and 15 wt. % KOH) and temperature (50 °C). Electrochemical impedance spectroscopy (EIS) was used to evaluate the ohmic and polarization resistances of the system and SEM was used to observe the morphology of prepared CCMs. Finally, a mid-term stability test was conducted in a single cell alkaline electrolyser. The obtained results show the possibility to achieve the high current densities with lower catalyst load and sufficient stability in mid-term experiments. CCM thus represents the promising way of improving of the alkaline water electrolysis technology.

Název v anglickém jazyce

Evaluation of the influence of the catalyst layer composition on the performance of the alkaline water electrolysis utilizing catalyst coated membrane based electrode membrane assembly

Popis výsledku anglicky

Alkaline water electrolysis represents promising technology for production of the green hydrogen. Advantages of the alkaline water electrolysis over the competitive technologies, such as polymer electrolyte membrane (PEM) or high temperature water electrolysis are several. Between main of them belongs: (i) it is a technology well established in industry, (ii) it does not require precious Pt group metals and (iii) availability of the construction materials. On the other hand, this technology does not achieve intensity and flexibility of the operation comparable to the PEM water electrolysis. This is due to the absence of the membrane based on anion selective polymer material able to ensure sufficient ionic contact between the electrodes and separation of produced gasses at the same time. Utilization of the anion selective polymer electrolyte membrane would allow not only to use zero gap arrangement, but even to deposit electrocatalytic layer directly on the surface of the membrane. Anion selective polymer binder has two vital roles. Firstly, it has to ensure the mechanical stability of the catalyst layer under the conditions of the rapid gas evolution. The second role is to ensure the ionic contact between the catalyst particles, especially in the environment of the diluted alkaline solutions or even demineralized water. Obviously, both can be met with high content of the polymer anion selective membrane in the layer. On the other hand, higher content of the anion selective polymer binder decreases the electronic contact between the catalyst particles which will results in the decrease of the performance of the alkaline water electrolysis. Proper composition of the catalyst layer thus represents critical issue. In this work, we study CCMs with various compositions of the catalyst layer. Air brush spraying at elevated temperature (50 °C) was chosen as a preparation method. The NiCo2O4 and NiFe2O4 were used as anode and cathode catalysts respectively at load 2,5 mg cm-2 which resulted in the thickness of the catalyst layer approximately 30 µm. Block copolymer polystyrene-ethylene-butylene-styrene (PSEBS) with 1,4-diazabicyclo[2.2.2]octane (DABCO) functional groups was used as the membrane and polymer binder of the catalyst layer. Performance of the alkaline water electrolysis in the form of the load curves was measured for all prepared samples with different potassium hydroxide concentrations (1, 5, 10 and 15 wt. % KOH) and temperature (50 °C). Electrochemical impedance spectroscopy (EIS) was used to evaluate the ohmic and polarization resistances of the system and SEM was used to observe the morphology of prepared CCMs. Finally, a mid-term stability test was conducted in a single cell alkaline electrolyser. The obtained results show the possibility to achieve the high current densities with lower catalyst load and sufficient stability in mid-term experiments. CCM thus represents the promising way of improving of the alkaline water electrolysis technology.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10405 - Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)

Projekt

<a href="/cs/project/FV10529" target="_blank" >FV10529: Pokročilá elektrolytická výroba vodíku z OZE</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů