Scientists supercharge promising material to catalyse clean hydrogen production

• Researchers at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, an autonomous institute under the Department of Science and Technology (DST), have devised a novel strategy for enhancing the activity of catalysts used to split water for generating hydrogen.

• Electrolysis is the process of using electricity to split water into hydrogen and oxygen. This reaction takes place in a unit called an electrolyser.

• Hydrogen is considered as one of the cleanest fuels.

• In the electrolysis of water, which is central to clean hydrogen production, the oxygen evolution reaction (OER) has long remained a challenge due to its sluggish kinetics and higher overpotential requirements compared to the hydrogen evolution reaction (HER).

• Developing noble-metal-free catalysts that can efficiently drive OER is therefore a pressing research priority.

• Coordination polymers (COPs) are formed by the combination of metal ions and organic molecules and are currently used for electrolysis of water. However, they have a limitation.

• Typically, such COPs are fully coordinated by solvent and water molecules, leaving few active sites for electrocatalysis and limiting their direct application.

• Now, the researchers have developed a new method to significantly enhance the catalytic activity of coordination polymers (COPs) without compromising their bulk structure.

• They employed argon plasma treatment, activating the COP. 

• This was possible due to generation of coordinatively unsaturated metal sites (CUMSs).

• The process enhanced catalytic performance while preserving the structural integrity and bulk structure of the polymer.

• Detailed structural studies revealed that the newly developed nickel and cobalt-based COPs were consistent across both single-crystal and bulk powder X-ray diffraction (XRD) analyses. 

• While the pristine materials displayed high onset potentials and sluggish performance for oxygen evolution in alkaline media, their activity was significantly boosted after argon plasma treatment. 

• The plasma process created coordinatively unsaturated metal sites (CUMSs) without altering the bulk framework, as confirmed by powder XRD, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements.

• The plasma-activated nickel and cobalt-based COPs demonstrated remarkable improvements in electrocatalytic performance.

• Advanced characterisation techniques, including X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, confirmed that the plasma treatment boosts the catalytic activity of nickel and cobalt-based COPs while preserving their core framework. 

• In practical tests, the treated catalysts showed markedly lower onset potentials and faster oxygen evolution in alkaline conditions compared to their untreated counterparts.

• The study was published in the journal ‘ACS Applied Nano Materials’.

(The author is a trainer for Civil Services aspirants.)