A Gilded Future?

Winter 2018


Image: Jaroslav Moravcik / Shutterstock

Johns Hopkins Engineering researchers are borrowing from the ancient Egyptian tradition of gilding to make fuel cells and other renewable energy technologies cheaper, better, and more sustainable.

Egyptians around the time of King Tutankhamun often covered cheaper metals (copper, for example) with precious metals such as gold to create extravagant masks and jewelry. In this modern-day twist, chemical and biomolecular engineer Chao Wang and his colleagues grew a platinum shell just one nanometer thick—100,000 times smaller than a human hair—on cobalt nanoparticles, producing a more sustainable electrocatalyst.

Cobalt is much more abundant and therefore cheaper than platinum, a rare and expensive metal widely used as a catalyst to accelerate chemical reactions. The innovation could bring clean energy—electric vehicles, for example—into reach for many more consumers through lowered costs, note the researchers, who recently published their work in Nano Letters.

“This technique could launch us out of the fossil fuel era,” says Wang, an assistant professor of chemical and biomolecular engineering and senior author of the study. “It will not only reduce the cost of fuel cells but also improve their performance, enabling clean electric vehicles powered by hydrogen.”

Lead author and postdoctoral fellow Lei Wang notes that platinum, also frequently used in jewelry, is a critical material in modern industry. It catalyzes reactions essential in activities ranging from petroleum processing and petrochemical synthesis to emission control in combustion vehicles, as well as in fuel cells. But platinum’s high cost and limited availability have made such clean energy technologies largely impractical—until now.

“There’s a lot more cobalt out there than platinum,” Lei Wang says. “We’ve been able to significantly stretch the benefits of platinum by coating it over cobalt, and we even managed to enhance its performance at the same time.”

Currently, the team is working on generalizing the technique to other precious metals and nonprecious substrates. New developments will target further applications of such materials in chemical conversions of hydrocarbons.

“Any reaction that depends on precious metal catalysts could be rendered cheaper and more effective by taking advantage of our technology,” Chao Wang says. “At a time when we are becoming painfully aware of the limits of our nonrenewable sources of energy, this technique points us in a very welcome new direction.”