A group of scientists from IIT-Madras’ Department of Physics recently made a significant advancement in the field of seawater electrolysis (Cost-Effective Hydrogen). The team, under the direction of Dr. Ramaprabhu Sundara, has created crucial elements that enable the efficient and affordable electrolysis of saltwater to produce hydrogen. The results of their investigation were just released in the ACS Applied Energy Materials journal.
It is well known that conventional alkaline water electrolysis technology consumes a lot of energy and uses fresh water and an expensive oxide-polymer separator. However, the IIT-Madras researchers have been able to overcome these difficulties by developing simple, scalable, and affordable alternatives that demonstrate excellent efficiency in seawater splitting and hydrogen production.
The team’s innovative method substitutes alkaline saltwater for clean or fresh water as an electrolyte. In addition, they have created carbon-based electrodes that dramatically reduce corrosion risk in comparison to traditional metal electrodes. Additionally, the researchers have created catalysts based on transition metals that successfully aid in oxygen and hydrogen evolution reactions. The catalysts improve hydrogen and oxygen generation even in the presence of contaminants and chemical buildup on the electrodes. They have developed a cellulose-based separator that efficiently blocks the passage of produced oxygen and hydrogen while permitting hydroxide ions to pass through to prevent crossover.
The water electrolysis device can now directly use photovoltaic-derived electricity to split seawater and produce green hydrogen and oxygen after the researchers made all parameters as efficient as possible. The creation of hydrogen, which can be utilised as a clean fuel source, could be revolutionised as a result of this discovery.
Overcoming difficulties when using seawater
At the anode and cathode, two half-reactions happen during the electrolysis process. Water splits into hydrogen ions (H+) and hydroxide ions at the cathode, where the H+ ions then undergo hydrogenation. Oxygen is produced at the anode as a result of the hydroxide ions leaking through the separator.
When saltwater is used for electrolysis, the creation of hypochlorite at the anode can result in corrosion of the electrode support material and disruption of the oxygen evolution reaction, which lowers the amount of oxygen produced. Impurities adsorbing on the electrode surface at the cathode can impede the hydrogen evolution reaction.
The researchers have used a carbon-based support material for the electrodes that are coated with the catalyst to get around these difficulties. The catalyst encourages the improved and concurrent synthesis of oxygen at the anode and hydrogen at the cathode. Reduced oxygen production is efficiently addressed by the transition bimetals in the catalyst, which show more selectivity towards the oxygen evolution process than hypochlorite creation.
A further benefit of the catalyst is that it helps to accelerate the hydrogen evolution reaction, which increases the amount of hydrogen produced by making up for impurities on the cathode.
The researchers’ creation of a unique separator is another outstanding aspect of their work. In alkaline electrolytes, the anode and cathode are often separated using zirconium oxide-based materials. The IIT-Madras team has developed a cellulose-based separator, though, that allows hydroxide ions to pass while reducing the crossing of produced hydrogen and oxygen. Notably, this separator has proven to be exceptionally resilient to seawater deterioration.
Source: Saur Energy
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