Synthesis of rod-type Co2.4Mn0.6O4 via oxalate precipitation for water splitting catalysts

•CMO based nanorods have been synthesized through an oxalate precipitation method.•The overpotential decreases from 425 mV at 10 mA cm−2 to 365 mV after the lower the annealing temperature.•The OER activity is improved due to the synergistic effect of large surface area and surface defects as catalytic active sites. Development of a cost-effective oxygen evolution reaction (OER) catalyst for hydrogen production from water has attracted the attention of scientists due to its potential to solve current environmental and energy issues, such as CO2 emissions and depletion of fossil fuels. In this paper, we report a facile synthesis to develop cobalt-manganese-oxide (MnxCo3−xO4, CMO) nanorods via an oxalate precipitation method followed by annealing at different temperatures. Importantly, morphology and surface area of the CMO nanorods, which are directly related to the OER activity, can be precisely controlled by changing annealing temperatures. The CMO nanorods engineered by oxalate precipitation and subsequent heat treatment show promising OER catalytic performance, such as a small overpotential of 365 mV for generating a current density of 10 mA cm−2, a low Tafel slope of 50.6 mV dec−1, and excellent long-term stability in alkaline media. Electrochemical properties combined with materials characterization provide insightful information on the OER mechanism of the CMO nanorods.