With the rapidly expanding economies, the urgent need for reliable energy transformation has emerged. Hydrogen, characterized by its zero carbon emissions and superior weight energy density, holds great promise for developing clean and sustainable energy sources in this energy conversion. Hydrogen could emerge as an alternative to fossil fuels.
Currently, water electrolysis is used for hydrogen and green hydrogen production. However, commercial water electrolyzers often require pure water to enhance their longevity, making them impractical in regions with limited freshwater supply.
“Electrochemical production of hydrogen through direct seawater splitting in selected locations has become a promising route due to the continuous depletion of fossil fuels and respective environmental concerns. However, this proposal for hydrogen production is significantly hindered by aggressive conditions posed by neutral seawater, resulting in the deactivation of the catalyst and severe damage to the plant facility.”
Therefore, seawater is favored as a strategic resource. Constituting 96.5% of the Earth’s water reserves with its high ionic conductivity, seawater eliminates the need for alkaline or acidic supplements, thereby decreasing the cost and enhancing efficiency.
However, the heterogeneous composition of seawater is a distinct and complex challenge for electrolysis. For instance, the unwanted supply of impurity ions like Cl−, SO42−, Ca2+, and Mg2+, alongside various microbes and bacteria, contributes to a host of adverse side reactions and corrosion issues. Specifically, Cl− aggressively corrodes the electrode, resulting in the ultimate performance failure of the catalyst. Also, the bacterial reaction might lead to catalyst poisoning.
To overcome the challenges, researchers have been developing cost-effective materials for electrocatalysis. 2D materials are considered a good candidate due to their exceptional charge transport efficiency, good electrical and thermal conductivities, and unique photon interactions.
2D materials’ tightly packed structures act as a barrier for Cl−, preventing access to the underlying electrode surface, and thereby stopping direct corrosion. Their chemically inert properties prevent any reaction with Cl−. 2D materials permit selective passage of ions. Therefore, researchers can use desired ions during electrochemical reactions.
The 2D materials are extremely lean, with a thickness of just a few atomic layers, and their metallic design can easily be manipulated to improve the electrocatalytic activity of catalysts for seawater splitting.
Their earth-abundant existence and because of their clear and well-defined structures make the 2D materials ideal for computational and experimental-based mechanistic studies.
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Use of 2D MXene for Seawater Splitting
MXene is a new class of 2D material made up of atomically thin layers of carbides, nitrides, or carbonitrides. The MXene is favored for its rich surface chemistry, superconductivity, higher thermal stability, and tunable electronic configurations, offering almost comparable electrocatalytic properties.
Journal Reference:
Fereja, S. L., Mehmood, A., Ji, Q., Raza, W., Hussen, A., Hu, J., Zhai, S., & Cai, X. Advancing the utilization of 2D materials for electrocatalytic seawater splitting. InfoMat, e12623. DOI: 10.1002/inf2.12623