Researchers led by chemistry professors Sen Zhang and T. Brent Gunnoe have produced a new form of catalyst for more efficient hydrogen hydrogen using the elements cobalt and titanium. The advantage of these elements is that they are much more abundant in nature than other commonly used catalytic materials containing precious metals such as iridium or ruthenium.
Argonne National Laboratory and the Lawrence Berkeley National Laboratory synchrotron X-ray absorption spectroscopy examined the structure and found that the catalyst has a well-defined surface structure that allows them to clearly see how the catalyst evolves in the meantime of the oxygen evolution reaction and allows them to accurately evaluate its performance.
Efficient electrocatalysts for the oxygen evolution reaction (OER) are paramount to the development of electrochemical devices for clean energy and fuel conversion. However, the structural complexity of heterogeneous electrocatalysts makes it a great challenge to elucidate the surface catalytic sites and OER mechanisms. Here, we report that catalytic single-site Co in a well-defined brookite TiO2 nanorod (210) surface (Co-TiO2) presents turnover frequencies that are among the highest for Co-based heterogeneous catalysts reported to date, reaching 6.6 ± 1.2 and 181.4 ± 28 s−1 at 300 and 400 mV overpotentials, respectively. Based on grand canonical quantum mechanics calculations and the single-site Co atomic structure validated by in situ and ex situ spectroscopic probes, we have established a full description of the catalytic reaction kinetics for Co-TiO2 as a function of applied potential, revealing an adsorbate evolution mechanism for the OER. The computationally predicted Tafel slope and turnover frequencies exhibit exceedingly good agreement with experiment.
SOURCES – University of Virginia, ANL, LBNL, Nature Catalysis
Written By Brian Wang, Nextbigfuture.com