A team of researchers from the Centre for Nano and Soft Matter Sciences (CeNS) have stressed that industrial waste would increasingly form the base for energy storage in batteries in the future.

The potential could open new strategies for optimal use of industrial waste for energy storage in batteries, paving the way to realize how to harness energy from waste.

Dr. C. Sathiskumar, Dr. Neena S. John, and Dr. H.S.S. Ramakrishna Matte, attached to the institute, have stressed that the spent catalysts from the energy industry or the raw material for recycling operation could work as an efficient bifunctional oxygen electrocatalyst. These materials deliver fresh catalysts and valuable metals and can catalyze the core reactions that facilitate the operation of metal-air batteries.

Experts from CeNS, an autonomous institute under the Department of Science & Technology, Government of India, led the research in collaboration with Hindustan Petroleum Corporation Ltd (HPCL) R&D Green Centre, Bengaluru.

The research has been published in the journal Sustainable Energy Fuels.

Owing to its high energy density and clean output, hydrogen energy forms an attractive energy option for the manufacturing and transport sectors. A common way to yield hydrogen is by catalytic decomposition of methane using a nickel catalyst embedded on alumina or zeolite. The drawback of this method is that the catalysts get spent due to carbon choking and lose functionality after several runs. The limitations make the process economically unviable and environmentally unfriendly.

An alternative method would be to use the retrieved spent catalyst for energy generation/storage applications, stressed the researchers.

The researchers elaborated how the spent catalyst works as an efficient bifunctional oxygen electrocatalyst.

The composition of the given spent catalyst, carbon nanotubes with Ni nanoparticles and porous alumina, could be ideal for direct use as an electrocatalyst in electrochemical energy applications.

The spent catalyst demonstrates stable current density for 20 hr and 8 hr towards oxygen evolution reaction and oxygen reduction reaction. These core reactions facilitate the operation of metal-air batteries. The potential difference for overall oxygen electrocatalyst (ΔE) reveals a superior bifunctional activity of the spent catalyst.

Furthermore, the spent catalyst employed in Zn-air batteries displayed commendable charge-discharge performance up to 45 hr, with high reversibility, providing a viable strategy for converting waste to wealth, said the researchers.

The search to yield and store energy led researchers from the International Advanced Research Centre for Powder Metallurgy and New Materials to develop a cost-effective electrocatalyst by anchoring transition metal ions into the sulfur-doped carbon framework via carbonization of a polymer called sulfonated polyether ether ketone (sPEEK).

Earlier, collaborative research between the University of Liverpool, United Kingdom, and National Tsing Hua University (NTHU), Taiwan, revealed a new charge storage mechanism that has the potential to allow rechargeability within calcium-air batteries.