Curcumin and gold nanoparticles key to ethanol fuel cells

This is the claim of researchers at the Clemson Nanomaterials Institute (CNI), South Carolina and their collaborators from the Sri Sathya Sai Institute of Higher Learning (SSSIHL) in India.

While the research team need to do more testing, the discovery could eventually lead to hydrogen being replaced as a fuel cell feedstock.

“Of all the catalysts for alcohol oxidation in alkaline medium, the one we prepared is the best so far,” said Apparao Rao, CNI’s founding director and the RA Bowen Professor of Physics in the Clemson's College of Science.

Hydrogen is the most common chemical element in the universe, but it must be derived from substances including natural gas and fossil fuels because it occurs naturally on Earth only in compound form. The necessary extraction adds to hydrogen fuel cells’ cost and environmental impact.

In addition, hydrogen used in fuel cells is a compressed gas, creating challenges for storage and transportation. According to CNI, ethanol - made from corn or other agricultural-based feeds - is safer and easier to transport than hydrogen because it is a liquid.

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“To make it a commercial product where we can fill our tanks with ethanol, the electrodes have to be highly efficient,” said Lakshman Ventrapragada, SSSIHL alumnus and research assistant at the CNI. “At the same time, we don’t want very expensive electrodes or synthetic polymeric substrates that are not eco-friendly because that defeats the whole purpose. We wanted to look at something green for the fuel cell generation process and making the fuel cell itself.”

The researchers focused on the fuel cell’s anode, where the ethanol or other feed source is oxidised.

Fuel cells widely use platinum as a catalyst, but the metal suffers from poisoning because of reaction intermediates such as carbon monoxide, Ventrapragada said in a statement. It is also costly.

Instead of using conducting polymers, metal-organic frameworks, or other complex materials to deposit the gold on the surface of the electrode, the researchers used curcumin - a substance in turmeric - because of its structural uniqueness. Curcumin is used to decorate the gold nanoparticles to stabilise them, forming a porous network around the nanoparticles. Researchers deposited the curcumin gold nanoparticle on the surface of the electrode at 100 times lower electric current than in previous studies.

Without the curcumin coating, the gold nanoparticles agglomerate, cutting down on the surface area exposed to the chemical reaction, Ventrapragada said.

“Without this curcumin coating, the performance is poor,” Rao said. “We need this coating to stabilise and create a porous environment around the nanoparticles, and then they do a super job with alcohol oxidation.

“There’s a big push in the industry for alcohol oxidation. This discovery is an excellent enabler for that. The next step is to scale the process up and work with an industrial collaborator who can actually make the fuel cells and build stacks of fuel cells for the real application,” he continued.

The electrode’s unique properties could also lend itself to future applications in sensors, supercapacitors and more, Ventrapragada said.

The team’s findings have been published in Nano Energy.