A team of researchers from India and the United States has combined curcumin, a molecule that was first extracted from the roots of Curcuma longa (turmeric), and gold nanoparticles to create an electrode that requires 100 times less energy to efficiently convert ethanol into electricity.

The green fuel (alcohol) is represented by the green-colored droplets at the top of the image, which upon interacting with curcumin enveloped gold nanoparticles, efficiently yield energy (white-colored sparks at the bottom of the image). Image credit: Sri Sai Prasad Nayak / Lakshman Ventrapragada.

Fuel cells generate electricity through a chemical reaction instead of combustion.

They are used to power vehicles, buildings, portable electronic devices and backup power systems.

Hydrogen fuel cells are highly efficient and do not produce greenhouse gases.

While hydrogen is the most common chemical element in the Universe, it must be derived from substances such as natural gas and fossil fuels because it occurs naturally on Earth only in compound form with other elements in liquids, gases or solids.

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.

Ethanol, an alcohol made from corn or other agricultural-based feeds, is safer and easier to transport than hydrogen because it is a liquid.

“To make it a commercial product where we can fill our tanks with ethanol, the electrodes have to be highly efficient,” said Dr. Lakshman Ventrapragada, a researcher in the Department of Physics and Astronomy at the Clemson Nanomaterials Institute.

“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.”

In their research, Dr. Ventrapragada and colleagues focused on the fuel cell’s anode, where the ethanol or other feed source is oxidized.

“Fuel cells widely use platinum as a catalyst. But platinum suffers from poisoning because of reaction intermediates such as carbon monoxide. It is also costly. We used gold as a catalyst,” Dr. Ventrapragada said.

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 because of its structural uniqueness.

Curcumin is used to decorate gold nanoparticles to stabilize them, forming a porous network around the nanoparticles.

The authors deposited curcumin gold nanoparticles on the surface of the electrode at a 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,” Dr. Ventrapragada said.

“Without this curcumin coating, the performance is poor. We need this coating to stabilize and create a porous environment around the nanoparticles, and then they do a super job with alcohol oxidation,” said Professor Apparao Rao, founding director of the Clemson Nanomaterials Institute.

“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.”

“But the research could have broader implications than improved fuel cells. The electrode’s unique properties could lend itself to future applications in sensors, supercapacitors and more,” Dr. Ventrapragada added.

The team’s work appears this month in the journal Nano Energy.

Sai Prasad Nayak et al. 2022. Green synthesis of a novel porous gold-curcumin nanocomposite for super-efficient alcohol oxidation. Nano Energy 94: 106966; doi: 10.1016/j.nanoen.2022.106966