Reviewed by Lexie CornerJul 16 2024
A research team at the Korea Institute of Science and Technology (KIST), in collaboration with the group at Sungkyunkwan University, developed an oxidatively stable molybdenum-based MXene as an electrocatalyst support in anion exchange membrane water electrolyzer. The study has been published in Applied Catalysis B: Environment and Energy.
The overall concept of catalyst design uses MXene as an electrocatalyst support and its use as an electrode for an anion exchange membrane water electrolyzer. Image Credit: Korea Institute of Science and Technology
One hundred thirty-seven nations have signed a global "net-zero" climate change agreement aimed at eliminating the use of fossil fuels and reaching zero carbon emissions by 2050. Since hydrogen only releases water and oxygen when used as an energy source, hydrogen is being hailed as the next big thing in green energy. Depending on the energy source and carbon emissions, there are three types of hydrogen production methods: gray, blue, and green.
The green hydrogen production method, which uses green energy to electrolyze water to produce hydrogen without carbon emissions, is the most environmentally friendly.
A research team led by Dr. Albert Sung Soo Lee of the Convergence Research Center for Solutions to Electromagnetic Interference in Future-Mobility and Materials Architecturing Research Center at Korea Institute of Science and Technology (KIST) in collaboration with the group of Professor Chong Min Koo at Sungkyunkwan University was involved in the study.
Its stability under oxidative, high-voltage conditions makes it suitable as an oxygen evolution reaction electrode material in electrolysis catalysts, potentially lowering green hydrogen production costs.
It takes a lot of energy to break down water into hydrogen and oxygen molecules. A catalyst is used to lower this initial reaction energy; the larger the catalyst's surface area, which permits the reaction to occur, the smaller the catalyst composed of minuscule nanoscale particles. However, tiny catalyst particles have the potential to group over time, decreasing the surface area and raising the inefficiency of hydrogen production.
Carbon, commonly used as a cathode material in hydrogen production, undergoes oxidation at the anode, forming carbon dioxide. To prevent this, catalysts and supports are employed. Consequently, a highly oxidation-resistant support is essential.
MXene is one substance that has the potential to be a support. MXenes are nanomaterials that are favorable for hydrogen production because they are made up of metal atoms (such as Ti, Mo, Hf, Ta, etc.) and carbon or nitrogen atoms. They also exhibit electrically conductive qualities and have a 2D nanostructure that can support catalysts. Since titanium-based MXenes have a high electrical conductivity, they have been studied the most. However, titanium's atomic nature—which makes it easily oxidized in water—has resulted in an inherent drawback: the catalyst's inability to maintain high electrical conductivity.
To overcome this, the group created a brand-new anode catalyst that employs MXene, a molybdenum carbide-based support. Strong chemical bonds are formed between the molybdenum atoms on the surface of the molybdenum-based MXene and the active material cobalt when it is used as a support. The efficiency of producing hydrogen was enhanced by approximately 2.45 times due to the chemical bonds that ensued. Specifically, the unit cell's durability was enhanced by over ten times compared to the outcomes of a recent titanium-based MXene, which lasted less than 40 hours.
This will be used in the future in large-scale hydrogen production facilities and large-scale green hydrogen power stations with the expectation that it will lower the cost of producing green hydrogen.
By controlling the elements that make up MXene, we were able to find suitable candidates for green hydrogen production environments, and through this, we secured a stable MXene support in an oxidizing environment. In the future, we will contribute to the revitalization of hydrogen-based economy by developing oxygen-generating electrode catalysts with catalytic efficiency and durability.
Dr. Albert Sung Soo Lee, Korea Institute of Science and Technology
Journal Reference:
Lee, S. S. A., et al. (2024) Unveiling the role of catalytically active MXene supports in enhancing the performance and durability of cobalt oxygen evolution reaction catalysts for anion exchange membrane water electrolyzers. Applied Catalysis B: Environment and Energy. doi.org/10.1016/j.apcatb.2024.123731