Caption: Nanogold clusters could be effective catalysts for hydrogen that will be used in fuel cells if they attract both carbon monoxide and oxygen. Zeng and colleagues quantified adsorption on nanogold clusters.Image: Xiao Cheng Zeng, University of Nebraska

Nanogold Clusters as Catalysts for Fuel Cell Hydrogen

January 30, 2012
Lincoln, Nebraska

Pure gold has a reputation as a stable and non-reactive element, but at the nanoscale - one-billionth of a meter - gold has a reactivity that could prove to be vital for alternative electricity generation.

In a recent publication in ACS Nano, scientist Xiao Cheng Zeng from the University of Nebraska-Lincoln collaborated with other scientists to predict the potential of pure gold nano molecules to aid in key reactions to produce hydrogen for fuel cells. Using complex computer modeling, they focused on gold clusters from 16 to 35 atoms in size. The results of the simulations are one piece of the puzzle for the grand challenge of meeting our energy needs from alternative sources.

Purifying Poison with Gold

Current methods of producing hydrogen gas for fuel cells result in the byproduct carbon monoxide. This byproduct can damage fuel cells - in fact, carbon monoxide is considered a fuel cell “poison.” But gold nanoparticles have the ability to speed up the conversion of carbon monoxide to carbon dioxide, which is benign in fuel cells, thereby refining the hydrogen gas to a purity that can be used.

“We consider the catalyst like a date. When you have two people date, they both must like the place to have chemistry,” Zeng explains.

In order to convert carbon monoxide to carbon dioxide, the gold nanoparticle has to attract both carbon monoxide and oxygen to its surface, bringing them together to make the magic happen.

Zeng and his collaborators found that some gold clusters attracted carbon monoxide, but didn’t attract oxygen as easily, and vice versa. Just a few clusters were found to attract both carbon monoxide and oxygen, and those are called “magic number clusters” - they offer the most potential to be used as a catalyst among the molecules that were studied.

Current nanogold catalysts are between 300-800 atoms. If scientists and engineers can synthesize molecules between 16-35 atoms, this could provide a tenfold savings by using smaller clusters to achieve the same catalytic effect.

On this nanogold simulation project, Zeng collaborated with Professor Zhongfang Chen at the University of Puerto Rico. Other collaborators include Zeng's former postdoc, Dr. Yong Pei, now a Professor at Xiantan University in China, and current postdoc Dr. Yi Gao at UNL, as well as a former student of Zeng's, Dr. Nan Shao of the Oak Ridge National Laboratory.

Zeng’s research was sponsored by a Nebraska NSF EPSCoR Track 2 Award, which is a collaborative project between scientists at the University of Nebraska and the University of Puerto Rico that focuses on computational nanoscience for energy technologies. The project takes advantage of the University of Nebraska’s supercomputer, allowing complex computations that would not be possible otherwise.

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Contact: Hanna Day-Woodruff
(402) 472-8944
hdaywoodruff2 at unl.edu

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