Scientists at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, have developed a new method to improve the efficiency of catalysts used in water electrolysis, a process central to clean hydrogen production. The work was carried out at an autonomous institute under the Department of Science and Technology and was recently published in the journal ACS Applied Nano Materials, the Ministry of Science & Technology has said.
According to the ministry, the research team sought to address a long-standing limitation in the oxygen evolution reaction, which is slower and requires higher over potential than the hydrogen evolution reaction, making it a bottleneck in water splitting. Coordination polymers, formed by combining metal ions with organic molecules, have been considered promising catalyst candidates, but their effectiveness has been constrained because they are typically saturated with solvent and water molecules, leaving few active sites available for catalysis.
To overcome this, it added that the scientists developed a process in which nickel- and cobalt-based coordination polymers were exposed to argon plasma. The treatment created coordinatively unsaturated metal sites on the surface of the materials, increasing their catalytic activity without altering the underlying bulk structure. Structural studies using single-crystal and powder X-ray diffraction confirmed that the framework remained intact, while additional characterisation through transmission electron microscopy, X-ray photoelectron spectroscopy and contact-angle measurements established the presence of new active sites.
The plasma-treated materials demonstrated substantially improved oxygen-evolution performance in alkaline media compared with untreated counterparts, showing lower onset potentials and faster reaction kinetics. According to the researchers, the approach provides a viable strategy for enhancing the intrinsic activity of noble-metal-free electrocatalysts for water splitting.
The findings, they said, open possibilities for developing more cost-effective and efficient catalytic materials for clean hydrogen generation.
