Engineering the morphology of ZnCo2O4 through different synthetic approaches for enhanced OER performance

Renewable energy research emphasizes engineering highly active electrocatalysts for oxygen evolution reaction (OER) to scale up electrocatalytic water splitting. The factors that govern the intrinsic OER activity of an electrocatalyst such as morphology and active sites can be tuned through appropriate synthesis approach. Herein, we report ZnCo2O4 electrocatalyst synthesized by Solution combustion (ZCO-C), sol-gel (ZCO-SG) and hydrothermal method (ZCO-H) and the effect of different synthesis routes on OER activity is investigated. In 1 M KOH, ZCO-C exhibited excellent OER activity with a low overpotential and Tafel slope of 330 mV at 10 mA cm−2 and 59.7 mV dec−1 respectively which is lower than reported literature on pristine ZnCo2O4. The superior OER activity of ZCO-C can be attributed to its higher crystallinity, enhanced electrochemical active surface area, higher active sites (Co3+/Co2+ ratio) and lower charge transfer resistance (Rct). The study highlights the crucial role of synthesis method in tuning the properties of the electrocatalysts towards OER.