A bi-functional catalyst for oxygen reduction and oxygen evolution reactions from used baby diapers: α-Fe2O3 wrapped in P and S dual doped graphitic carbon

Abstract

The development of energy conversion and storage devices and the disposal of solid waste represent two major challenges for environmental sustainability. The development of many key sustainable energy technologies relies on fast oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics. However, both reactions are sluggish. In the present work, we address these two issues synergistically by fabricating Fe₂O₃ wrapped in P and S dual-doped graphitized carbon (Fe₂O₃/P–S-CG) from soiled baby diapers, whose disposal and recycling are beneficial to the environment. Electrochemical tests revealed that Fe₂O₃/P–S-GC has a significant catalytic activity towards both the ORR and OER in 0.1 M KOH. In particular, the difference between the ORR potential at 3 mA cm⁻² and the OER potential at 10 mA cm⁻² is as small as ∼0.86 V. This value is comparable to that of commercial precious metal-based catalysts. In addition, Fe₂O₃/P–S-GC exhibits a favorable catalytic durability, making it a promising bi-functional non-precious catalyst for the ORR and OER.