Tri-functional Fe-based electrocatalyst with sturdy three-dimensional frame construction for the ORR, OER and HER

Abstract

Oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrocatalysis have an important role in rechargeable zinc–air batteries (ZABs) and water splitting and have received extensive attention over the years. Therefore, the design and development of efficient and economical multifunctional electrocatalysts is currently considered an important subject in the field of green and renewable energy. In this paper, a simple and reproducible SiO₂ templating strategy is designed to utilize natural hemin as a source of Fe–N–C material. Hemin is adsorbed onto the surface of SiO₂ through electrostatic interaction, which allows hemin to stretch along the surface of SiO₂ spheres during high-temperature pyrolysis. The final product named Fe₃C–Fe/NC-800 with abundant cavities and a sturdy 3D framework structure shows excellent ORR, OER and HER activities. Theoretical calculations show that the synergistic interaction between Fe₃C and FeN₄ sites reduces the energy barrier during the electrochemical reaction and improves the ORR, OER, and HER performance. Based on its superior tri-functional activity, Fe₃C–Fe/NC-800 finds potential applications in ZABs and overall water-splitting devices. This work will provide insights into the design and preparation of electrocatalysts used in clean energy conversion devices.