Simulations provide new insight into water structure and dynamics at the water-cobalt oxide interface
Simulations provide new insight into water structure and dynamics at the water-cobalt oxide interface lead image
The oxygen evolution reaction (OER), which is capable of liberating oxygen from water molecules, is a key step in producing green sustainable energy through water splitting. In the search for more efficient catalysts for such a reaction, solid cobalt oxides have shown promise for catalyzing the reactions at sufficiently low overpotentials. Liquid water’s role at the interface with cobalt oxides, however, remains poorly understood. New molecular simulations look to help explain the energetics and mechanisms at these interfaces.
Creazzo et al. have characterized the chemical and physical properties of the interface between water and (110)-Co3O4. Using molecular dynamics simulations based on density functional theory and the calculation of experimental observables such as Sum Frequency Generation (SFG) spectra and work function, the group’s work provides a clearer picture on how this semiconductor interacts with water.
“Previous theoretical investigations on these oxides did not include explicit water, and therefore could especially not manage the view about the ‘disciplined’ and ‘undisciplined’ liquid water at these interfaces,” said Marie-Pierre Gaigeot, an author on the paper.
The theoretical SFG spectroscopy reveals the structure and orientation of the water molecules at the various cobalt oxide surfaces considered. Additionally, the paper demonstrates the first spectroscopic markers for “undisciplined” water at the B-termination, a key for OER, Gaigeot said. The authors use the term undisciplined to describe water molecules that are disobedient to the electrostatic potentials imposed upon them.
The efforts represent one of the first attempts to understand the mechanism between these two materials, and the authors look to use it as a preliminary step toward modeling the interface in more applicable ways and finding the best semiconductor for water splitting.
Source: “DFT-MD of the (110)-Co3O4 cobalt oxide semiconductor in contact with liquid water, preliminary chemical and physical insights into the electrochemical environment,” by Fabrizio Creazzo, Daria Ruth Galimberti, Simone Pezzotti, and Marie-Pierre Gaigeot, The Journal of Chemical Physics (2019). The article can be accessed at https://doi.org/10.1063/1.5053729 .
