Structural and Catalytic Effects of Iron- and Scandium-Doping on a Strontium Cobalt Oxide Electrocatalyst for Water Oxidation

The poor kinetics of the oxygen evolution reaction (OER) are a considerable barrier to the development of water-derived hydrogen fuel. Previous work regarding theoretical calculations of the perovskite SrCoO3-delta(SCO) predicts a surface binding energy ideal for OER catalysis but could not be matched to experimental results due to the material's propensity to form the incorrect trigonal crystal structure. By doping with iron and scandium, X-ray diffraction confirms that we have been able to synthesize a series of SCO catalysts of various crystal structures, culminating in cubic SCO. In doing so, we show that there is a limited correlation between the crystal structure and OER performance in alkaline media. Instead, the use of iron as a dopant is found to decrease the OER overpotential of the SCO by 40 mV in 0.1 M KOH and yield catalysts capable of performing water oxidation at an overpotential of 410 mV at 10 mA/cm(2). The doped, cubic SCO catalysts are found to be more stable than the undoped material when tested for extended periods, showing only an approximate 3 mV increase in overpotential over a 2 h period at 10 mA/cm(2). Our results show that proper doping of the B-site cation in SCO allows for tuning the structure, performance, and stability of the oxide as an OER electrocatalyst.