The real-time investigation of the nickel–iron hydroxide catalyzed oxygen evolution reaction with interdigitated array electrodes

Electrocatalysis of oxygen evolution reaction (OER), one of the most important members in clean and efficient energy conversion, requires increasing studies on reaction process analysis, catalyst investigation and evaluation and so on throughin situexperiments. The bottleneck is the difficulties on clear and precise understanding towards the multi-step reactions with fast reaction rates. Interdigitated array (IDA) electrodes with sensitive responses on the generation, transfer and collection of reaction products are proposed and utilized as a convenient and effective tool toin situmonitor and characterize the reaction thermodynamics and kinetics information. Herein, nickel-iron hydroxide, a promising and novel OER catalyst, is chosen as the candidate to demonstrate the merit of IDA on studying the OER. With the generator-collector mode, the real-time oxygen evolution process is monitored precisely with the IDA collector, distinguished it from the general catalytic current which is normally recorded with conventional electrochemical method. In another word, the actual faradaic efficiency was observed experimentally with IDA electrodes, which is often misled as 100% in many works. The diffusion of the reaction products has been 'seen' as well with the generator-collector mode. This general tool (IDA) may make more contributions on the study of reaction process of all electrocatalytical reactions.