Oxygen evolution catalysis in alkaline conditions over hard templated nickel-cobalt based spinel oxides

Abstract In this work, two series of cobalt-based spinel catalysts, Co 3 O 4 and NiCo 2 O 4 , were synthesised by a hard template method with SBA-15 and were investigated as non-noble catalysts for the oxygen evolution reaction (OER) under basic conditions. The effect of synthesis conditions, i.e., heating rate and calcination temperature, and the addition of minor amounts of iron were evaluated with respect to the OER activity. Moreover, the influence of the alkali cation type in the electrolyte (Li, Na, K) was also evaluated. The highest activity was found for the NiCo 2 O 4 obtained with the lowest heating rate. The increase in the heating rate and calcination temperature results in the decrease of the available surface area for the reaction, leading to the deterioration of the activity. The incorporation of 3 wt% of iron in the lattice of NiCo 2 O 4 and Co 3 O 4 resulted in a decrease of the OER activity, however, the deactivation was much less severe in the case of NiCo 2 O 4 than for Co 3 O 4 . Among the alkaline electrolytes used, KOH resulted in the highest catalytic activity both for NiCo 2 O 4 and Co 3 O 4 .