The dream of a hydrogen economy—a world run on H2 gas, free from the pollution and politics of fossil fuels—may depend on developing an energy-efficient strategy for splitting water into oxygen and hydrogen. The problem is that water bonds are very stable, requiring hefty energy inputs to break. Scientists are eagerly developing catalysts to lower the energy demands, and thus the cost, of H2 production. Yet, they still struggle with the basics, such as what structural properties make a good water-splitting catalyst.
Using measurements from the Materials Research Collaborative Access Team (MR-CAT) 10-ID-B beamline and the X-ray Science Division 12-ID-C,D beamline at the U.S. Department of Energy Office of Science's Advanced Photon Source (APS), researchers analyzed the stability and composition of three small clusters of palladium—Pd4, Pd6, and Pd17—which are under investigation as potential water-splitting catalysts. They then generated structural models of the catalysts. By combining information about the identity and structure of each cluster with its catalytic activity, the researchers identified a particular Pd-Pd bond that appears to be essential for catalytic function. This research will allow scientists to design better water-splitting catalysts.