Reducing energy barriers to chemical reactions

Scientists have discovered that certain chemical reactions on the surface of metal oxides could be key in developing more efficient energy systems.

Such systems could include solar cells that would produce more electricity from the sun’s rays, or hydrogen fuel cells efficient enough for use in automobiles,

Historically, chemical reactions that change the oxidation state of molecules on the surface of metal oxides have been seen as a transfer solely of electrons.

Research and manufacturing have grown up around models in which electrons moved but not atoms

The new research shows that, at least in some reactions, the transfer process includes coupled electrons and protons.

“Research and manufacturing have grown up around models in which electrons moved but not atoms,” said James Mayer, a University of Washington chemistry professor.

His research proposes a different model for certain kinds of processes.

Coupling the transfer of electrons with the transfer of protons could help reduce the energy barriers to chemical reactions important in many technologies.

For example, using solar energy to make fuels such as hydrogen requires that electrons and protons be coupled.

The new perspective could be important for photocatalytic chemical processes, including those designed for wastewater remediation or to create self-cleaning surfaces, such as the outside of buildings in areas with heavy industrial air pollution.

The research focused specifically on nanoparticles, measured in billionths of a meter, of titanium dioxide and zinc oxide.

The new perspective could be important for photocatalytic chemical processes, including those designed for wastewater remediation

Titanium dioxide is the most common white pigment, used in paints, coatings, plastics, sunscreen and other materials.

Zinc oxide also is used in pigments, coatings and sunscreens, as well as white athletic tape, and also is used in the manufacture of rubber, concrete and other materials.

Nanocrystals were used to closely examine chemical processes at the material’s surface.

Mayer said the goal of the research is to get those working in various technological areas involving metal oxides to think in different ways about how those technologies work and how to make them more efficient.

“Chemical fuels are very useful, and they’re not going away,” Mayer said. “But how do we utilise them better in a non-fossil-fuel world?”