Cost-Effective, Efficient Hydrogen From Seawater Possible: Researchers, IIT Madras

In a significant development, a team of researchers from the Department of Physics at IIT-Madras has achieved a major breakthrough in the field of seawater electrolysis. Led by Dr. Ramaprabhu Sundara, the team has successfully developed critical components that enable the efficient and cost-effective electrolysis of seawater to generate hydrogen. The findings of their study were recently published in the journal ACS Applied Energy Materials.

Traditional alkaline water electrolysis technology is known to be energy-intensive, requiring an expensive oxide-polymer separator and fresh water for the process. However, the IIT-Madras researchers have managed to address these challenges by introducing simple, scalable, and cost-effective alternatives that exhibit high efficiency in splitting seawater and producing hydrogen.

The team’s groundbreaking approach involves the use of alkaline seawater as an electrolyte instead of pure or fresh water. Additionally, they have developed electrodes supported by carbon-based materials to significantly minimize the risk of corrosion compared to conventional metal electrodes. Furthermore, the researchers have designed transition metal-based catalysts that effectively facilitate both oxygen and hydrogen evolution reactions. Even when impurities and chemical deposition occur on the electrodes, the catalysts enhance the production of hydrogen and oxygen. To prevent crossover, they have created a cellulose-based separator that allows hydroxide ions to pass through while effectively blocking the passage of generated oxygen and hydrogen.

To maximize efficiency, the researchers have optimized all parameters so that the water electrolysis system can directly utilize photovoltaic-derived voltage to split seawater and generate green hydrogen and oxygen. This breakthrough has the potential to revolutionize the production of hydrogen, which can be used as a clean fuel source.

Overcoming challenges of using seawater

The electrolysis process involves two half-reactions occurring at the anode and cathode. At the cathode, water dissociates into H+ and hydroxide ions, with the H+ ions subsequently converting into hydrogen. The hydroxide ions permeate through the separator, leading to the generation of oxygen at the anode.

When seawater is used for electrolysis, the formation of hypochlorite at the anode can cause electrode support material corrosion and interfere with the oxygen evolution reaction, resulting in reduced oxygen production. At the cathode, impurities adsorbed on the electrode surface can slow down the hydrogen evolution reaction.

To overcome these challenges, the researchers have employed a carbon-based support material for the electrodes, which is coated with the catalyst. The catalyst promotes enhanced and simultaneous production of hydrogen at the cathode and oxygen at the anode. The transition bimetals in the catalyst demonstrate greater selectivity towards oxygen evolution reaction compared to hypochlorite formation, effectively addressing the issue of reduced oxygen production. Additionally, the catalyst aids in promoting the hydrogen evolution reaction, compensating for the presence of impurities on the cathode and leading to increased hydrogen production.

Novel Separator

Another remarkable feature of the researchers’ work is the development of a novel separator. Typically, the anode and cathode are separated using zirconium oxide-based materials in alkaline electrolytes. However, the IIT-Madras team has introduced a cellulose-based separator that allows the passage of hydroxide ions while minimizing the crossover of generated hydrogen and oxygen. Notably, this separator has demonstrated excellent resistance to seawater degradation.