Researchers at the Clemson Nanomaterials Institute (CNI) and their collaborators from the Sri Sathya Sai Institute of Higher Learning (SSSIHL) in India discovered a novel way to combine curcumin—the substance in turmeric—and gold nanoparticles to create an electrode that requires 100 times less energy to convert ethanol or methanol into electricity efficiently.

While the research team must do more testing, the discovery brings replacing hydrogen as a fuel cell feedstock one step closer. A paper on their work is published in the journal Nano Energy.

Gold nanoparticles (AuNPs) possess tunable size- and shape-dependent properties that are ideal for catalytic properties for many applications. However, the challenge lies in the synthesis of highly stable and ultra-small NPs. We report an energy-efficient galvanostatic route to engineer gold-curcumin (Au-CM) nanocomposites constituting small-sized (~2 nm) AuNPs enveloped by a porous network of curcumin.

… The Au-CM/GCE nanocomposite exhibited excellent stability (~200 cycles), facile electron transfer ability, catalytic activity, and low Arrhenius energy of 42 and 45 kJ mol⁻¹, respectively, towards electrooxidation of EtOH and MeOH in alkaline medium. The oxidation kinetics are comparable to those of the best gold-polymer composites. This study points the way for one-pot green synthesis of other engineered electrocatalysts for different applications.

—Nayak et al.

The researchers focused on fuel cell anodes, 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.

The researchers used gold as a catalyst. 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 the gold nanoparticles to stabilize them, forming a porous network around the nanoparticles.

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

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. 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

—Apparao Rao, CNI’s founding director and co-corresponding author

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, Ventrapragada said.

Resources

• Sai Prasad Nayak, Lakshman K. Ventrapragada, Sai Sathish Ramamurthy, J.K. Kiran Kumar, Apparao M. Rao (2022) “Green synthesis of a novel porous gold-curcumin nanocomposite for super-efficient alcohol oxidation,” Nano Energy doi: 10.1016/j.nanoen.2022.106966