Electrocatalytic water splitting may play a significant future role in energy sustainability. Not surprisingly there has been an intense effort in developing catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) that make up the water splitting process. The rational design of catalysts using density functional theory based computation and prediction have played a large role in the development of catalysts for both the OER and HER. Research will be presented that highlights how the integration of theory, computation, and experiment has led to the development of novel catalytic systems based on the nanoconfinement of catalytic metal in 2D layered metal oxides and layered double hydroxides. DFT based calculations have shown that the 3D environment of the interlayer provides a unique environment for the redox chemistry involving water and intercalated catalytic sites. As an example, nanoconfined cobalt in 2D layered MnO2 provides an environment where the energetics of OER intermediates become more favorable for water oxidation than if cobalt is adsorbed on the surface of planar MnO2 sheets. Cobalt (12.2 at. %) intercalated into the interlayer of birnessite exhibits an overpotential (η) of 360 mV for OER at an anodic current of 10 mA/cm2. This η is lower than the η values for birnessite (η ~770 mV) and the active OER catalyst α-Co(OH)2 (η ~380 mV). Experimental and DFT based results will also be shown that demonstrates that this confinement of catalytic metal in the interlayer of 2D layered materials can be used to develop low loading precious metal based OER and HER catalytic systems that are stable in both acidic and basic environments.

Nanoconfined catalytic sites in 2D layered metal oxides for electrocatalytic water splitting

ACS Fall 2021

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