AVS 64th International Symposium & Exhibition
    Surface Science Division Monday Sessions
       Session SS+AS+HC-MoA

Paper SS+AS+HC-MoA8
Active Species and Structures of Modified Oxide Catalysts for the Oxygen Evolution Reaction (OER)

Monday, October 30, 2017, 4:00 pm, Room 25

Session: Surface Science for Energy and the Environment
Presenter: Bruce Koel, Princeton University
Authors: Z. Chen, Princeton University
L. Cai, Xi’an Jiaotong University, China
B.E. Koel, Princeton University
Correspondent: Click to Email
Transition metal oxides (TMOs) are promising catalysts for oxygen evolution with the potential to replace precious metal-based catalysts (e.g. IrOx and RuOx). Significant improvements to the OER activity of TMOs have been made by tailoring the morphology and crystal structure of the catalysts, incorporating dopants, as well as using conductive supports. However, clear structure-activity correlations remain elusive because of the complex composition and structure of TMO catalysts. In this contribution, we utilizing a range of spectroscopic techniques for characterization of Ce-modified copper oxide (CuOx) and Ni-modified cobalt (oxy)hydroxides to reveal the OER active species and structures of these catalysts. In the case of Ce-modified CuOx, Ce incorporation (6.9 at%) into CuOx led to 3.3 times greater OER activity compared to pure CuOx and this is coincident with significant structural changes due to an increasing amount of disorder. By combining X-ray photoelectron and Raman spectroscopy techniques, a strong correlation between OER performance with tetravalent Ce (Ce4+) ions was observed up to a concentration corresponding to CeO2 phase segregation. We propose a strong promoting effect of Ce4+ for OER in this system. In the case of Ni-modified CoOxHy, operando Raman spectroscopy was used to reveal a drastic transformation of a spinel Co­3O4-like structure into a more active (oxy)hydroxide structure under applied potential. Such a transformation was only observed in the presence of uniformly distributed Ni ions. These two examples, i.e. the promoting effect of Ce4+ and the formation of active OER structures in Ni-modified CoOxHy, reveal the importance of chemical state and local structure considerations for the rational design of OER oxide-based OER catalysts.