A quick guide to the assessment of key electrochemical performance indicators for the oxygen reduction reaction: A comprehensive review

Oxygen reduction reaction (ORR) is a vital electrochemical reaction for energy conversion that has fascinated the interest of materials researchers to promote active and cost-effective electrocatalysts with improved reaction kinetics. Numerous, researches have been undertaken to achieve the desired characteristic cathode materials to revolutionize energy conversion devices including fuel cells and metal-air batteries (where ORR occurs). More importantly, the evaluation of electrocatalyst efficiency for ORR using typical electrochemical experiments, data collection, and analysis must be performed systematically and uniformly. This review provides a systematic guide to assess the electrochemical efficiency because it includes standard and widely recognized experimental protocols for each electrochemical technique, as well as easy-to-follow lab procedures and a detailed analysis of essential kinetic ORR parameters with a theoretical framework. The major function of each electrode in cyclic voltammetry, hydrodynamic linear scan voltammetry with rotating disc electrodes, and electrochemical impedance spectroscopy for ORR were demonstrated, as well as the construction of a three-electrode electrochemical cell. By following standard protocols and experimental procedures, an aspiring electrochemist would be capable to enforce fundamental and advanced electrochemical techniques much efficiently in their understanding of ORR kinetics evaluation.