Cobalt-Based Mixed Metal Oxide Catalysts for the Oxygen Evolution Reaction

Current methods of hydrogen production release an average of 12-13 kg CO2 per kg H2 produced; with fossil fuel-based production generating up to 27 kg CO2 per kg H2. An alternative process known as water electrolysis, has the potential to reduce CO2 emission per kg of H2 produced. In this process, the oxygen evolution reaction (OER) is the bottleneck limiting the rate of hydrogen production and the overall process efficiency. The sluggish reaction kinetics of OER can be improved through the use of mixed metal oxide catalysts which can improve device efficiency and reduce capital costs. Cobalt oxide has been found to be an effective catalyst for OER in alkali conditions, however, it has low activity and stability in lower pH conditions.

Herein, we aim to improve the activity and stability of cobalt oxide thin-film electrocatalysts for OER by changing the chemical compositions and solid state structures. We explored different thermal treatment conditions and heteroatoms doping strategies (e.g., manganese) to stabilize the cobalt oxide thin-film. We evaluated the activity and stability of the resultant catalysts under different pH conditions and found that activity is negligible in any electrolyte less than pH 13. The production of an active, affordable, and stable catalyst will incentivize greater penetration of the water electrolysis technology.