Hydrogen is often hailed as the fuel of the future, offering a clean energy solution that could play a central role in decarbonising industries and transport. But producing hydrogen sustainably remains a challenge, and the key lies in electrocatalysis—the process of splitting water (H₂O) into hydrogen and oxygen using catalysts that reduce the energy required.

Currently, platinum-based catalysts are the gold standard in terms of efficiency. Platinum is highly effective, but it comes with two major drawbacks: scarcity and cost. The expense of platinum makes it impractical for scaling up green hydrogen production to the levels needed to support a global transition to clean energy. This has prompted researchers worldwide to look for alternatives among more abundant and affordable metals such as nickel, iron, cobalt, copper, and zinc.

At Ashoka University, a team has been investigating whether these metals, when combined with ligands, can provide a viable substitute for platinum. In chemistry, a ligand is a molecule that binds with a metal ion to form a complex. In biochemistry, haemoglobin provides a familiar example: oxygen acts as a ligand when it binds with iron to transport oxygen through the body. 

The team tested several metal-ligand complexes, including those based on nickel, copper, cobalt, zinc, and iron. Among these, the nickel-ligand combination showed the greatest promise for efficient hydrogen generation. Two scientific measures were used to assess the performance of these catalysts: overpotential and turnover frequency.

Overpotential refers to the additional energy needed, beyond the theoretical minimum, to drive the chemical reaction. A lower overpotential means that the process requires less energy, making it more efficient. Turnover frequency, on the other hand, measures how quickly the catalyst produces hydrogen; a higher turnover frequency indicates greater productivity. The nickel-ligand complex excelled on both counts, demonstrating lower overpotential and competitive turnover frequencies compared with other metal-ligand systems.

This raised an important question: why use ligands at all, rather than just the metals themselves? Dr. Munmun Ghosh, a member of the team, provides the answer: “My overpotential will be much higher with just the metal. A ligand helps decrease the overpotential and make the process more efficient.” In other words, ligands are the key to unlocking better performance from relatively common metals.

The study underscores how nature-inspired scientific research can deliver practical solutions to some of the world’s biggest challenges. As demand for clean hydrogen grows, innovations like nickel-ligand catalysts may help make the vision of affordable, sustainable hydrogen a reality.

Source:

https://www.thehindubusinessline.com/business-tech/ligand-catalysts-show-promise-in-quest-for-green-hydrogen/article69968038.ece