Novel Iron/Cobalt-Containing Polypyrrole Hydrogel-Derived Trifunctional Electrocatalyst for Self-Powered Overall Water Splitting

Development of efficient, low-cost, and durable electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is of significant importance for many electrochemical devices, such as rechargeable metal-air batteries, fuel cells, and water electrolyzers. Here, a novel approach for the synthesis of a trifunctional electrocatalyst derived from iron/cobalt-containing polypyrrole (PPy) hydrogel is reported. This strategy relies on the formation of a supramolecularly crosslinked PPy hydrogel that allows for efficient and homogeneous incorporation of highly active Fe/Co-N-C species. Meanwhile, Co nanoparticles are also formed and embedded into the carbon scaffold during the pyrolysis process, further promoting electrochemical activities. The resultant electrocatalyst exhibits prominent catalytic activities for ORR, OER, and HER, surpassing previously reported trifunctional electrocatalysts. Finally, it is demonstrated that the as-obtained trifunctional electrocatalyst can be used for electrocatalytic overall water splitting in a self-powered manner under ambient conditions. This work offers new prospects in developing highly active, nonprecious-metal-based electrocatalysts in electrochemical energy devices.