Turning carbon dioxide into biofuel is a key interest for scientists who are trying to find more environmentally friendly options for energy as well as ways to reduce greenhouse gases.

Researchers at the University of Delaware have achieved a new milestone in this endeavor with a new approach to catalysis for reducing carbon dioxide to methane, the base ingredient for natural gas.

A special surface of copper and silver, shown here, was key to a new method for reducing carbon dioxide to methane developed by University of Delaware researchers. (Source: University of Delaware)

The method solves a key challenge to turning carbon dioxide into fuel, achieving a “one step conversion from carbon dioxide to methane in neutral pH,” Bingjun Xu, assistant professor of chemical and biomolecular engineering at the university, told Design News.

Converting carbon dioxide into valuable fuels starts with a surface made of copper, which can be used to reduce carbon dioxide into carbon monoxide. Then, the carbon monoxide typically is transformed to methane and other gases. While this process is not extremely complicated, it requires two reactors as well as costly separation and purification steps, researchers said.

The new approach—one researchers designed using computations and experiments—eliminates this complexity, Xu said. In the one-pot catalysis system his team designed, all that’s needed is to add carbon dioxide to the copper surface, and a series of chemical reactions will occur to reduce the gas to methane without the need for more chemicals, Xu said.

Silver Lining

The new method relies on previous research by Qi Lu of Tsinghua University in China, formerly a postdoctoral associate working with Xu. During his time at the University of Delaware, Lu developed special nanostructured silver surfaces that researchers added to the copper surfaces in the new catalysis method.

The silver portion attracts carbon monoxide molecules, which then migrate to the copper portion and reduce to methane, creating a system in which “bimetallic catalysts are capable of facilitating tandem catalysis,” Xu told Design News. The system yields a higher concentration of methane than copper-only systems, he said.

The team published a paper on its work in the journal Nature Communications.

Although the approach sounds somewhat simple, researchers did face a key challenge. While previous attempts to combine copper with precious metal in similar ways have failed, Xu’s team developed a special type of electrode structure to overcome this problem, he said. Xu cited a cross-disciplinary team that used a combination of spectroscopy, computation, and studies of material reactivity as key to this success.

Researchers hope their method will facilitate the development of fuels and other materials from carbon dioxide to “make renewable carbon-dioxide reduction more economical” in the pursuit of renewable energy sources, he told Design News.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.