Principal Investigator Yang Shao-Horn
The efficiency of many energy storage technologies, such as rechargeable metal-air batteries and hydrogen production from water splitting, is limited by the slow OER kinetics on the transition metal oxide surfaces. While substantial effort has been devoted to understanding the mechanism and parameters that govern the OER activity and ideally discovering a convenient activity descriptor, it is still not straightforward to predict transition metal oxides with high OER activity by means of these previous works. Motivated by the ab initio study of Rossmeisl, whose work suggests a universal relationship between the OER activity on the ORR activity, we have recently identified unique catalyst properties (“activity descriptors”) of the OER activity of transition-metal-oxide-based catalysts (namely eg of trqansition metal ions) which can predict a highly efficient OER transition-metal-oxide-based catalyst. Using the eg framework, we predict a highly effective OER catalyst at an eg occupancy close to unity, with high covalency of transition metal–oxygen bond. One candidate that fulfills this criterion is Ba0.5Sr0.5Co0.8Fe(0.2O3-delta), which we found to have a corresponding high OER activity. Our finding reveals that the ORR descriptor can be used for the OER, in agreement with the prediction by Rossmeisl and co-workers.
There are several areas of research currently under investigation in our lab. We are interested in the discovery and characterization of new photoelectrode materials (with a focus on using in situ methods), as well as the optimization and stabilization of existing candidates such as various oxides and III-V materials. In addition, we are utilizing our previous experience in oxygen evolution catalysis to investigate the integration of co-catalyst materials on silicon photoelectrochemical cells, as well as the properties of the interfaces between co-catalyst, photoelectrode and electrolyte. The overarching goal is a set of design principles derived from a fundamental understanding of the processes and loss mechanisms in these devices.