A new strategy has been developed to enhance the performance of catalysts used in water splitting for hydrogen generation—one of the cleanest known fuels. In water electrolysis, the oxygen evolution reaction (OER) has long posed challenges due to its sluggish kinetics and higher overpotential requirements compared with the hydrogen evolution reaction (HER). Creating efficient, noble-metal-free catalysts for OER remains a key research priority.

Coordination polymers (COPs), formed through the combination of metal ions and organic molecules, are widely explored for water electrolysis. However, their full coordination by solvent and water molecules leaves very few active sites for electrocatalysis, limiting their direct applicability.

Researchers at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru—an autonomous institute under the Department of Science and Technology—have now devised a novel approach to significantly enhance the catalytic activity of COPs while preserving their structural framework.

Their method uses argon plasma treatment to activate the polymer by generating coordinatively unsaturated metal sites (CUMSs). These newly created active sites greatly improve catalytic performance without compromising the bulk structure.

Detailed structural investigations confirmed that the Ni- and Co-based COPs retained their integrity across single-crystal and bulk powder X-ray diffraction analyses. While the untreated materials showed high onset potentials and limited OER activity in alkaline media, their performance improved substantially after plasma activation. Powder XRD, TEM imaging, XPS analysis and contact-angle studies verified that the bulk structure remained unchanged despite the formation of CUMSs.

The plasma-activated Ni- and Co-COPs displayed marked enhancements in electrocatalytic activity, demonstrating an effective approach to elevate the intrinsic efficiency of coordination-polymer-based catalysts.

Published in ACS Applied Nano Materials, this work opens new avenues for designing cost-effective, high-performance catalysts for water splitting, supporting broader efforts to advance clean and sustainable hydrogen energy.