Waste iron-based disposable chemical warmer derived electrocatalyst for water splitting

Abstract

Recycling solid waste into electrocatalysts for renewable energy systems is crucial for sustainable development, achieving a win-win strategy for environmental remediation and waste utilization. The global use of iron-based disposable chemical warmers results in the generation of a significant amount of solid waste. This study demonstrates the upcycling of disposed iron-based chemical warmers into bifunctional Fe/Fe₃O₄/NC electrocatalysts. The synthesized catalysts exhibited excellent electrocatalytic activity for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Fe/Fe₃O₄/NC for HER and OER performance requires overpotentials of only 160 and 230 mV, respectively, to achieve 10 mA cm⁻². This catalyst exhibited excellent bifunctional performance, achieving a low cell voltage of 1.53 V to reach a current density of 10 mA cm⁻² for overall water splitting. The synergistic interaction of the metal–metal oxide (Fe–Fe₃O₄) interface and N-doped carbon significantly enhances the catalytic activity. This work synergistically addresses the sustainable utilization of waste materials, contributes to resource conservation, reduces energy consumption in iron ore mining processes, and mitigates environmental pollution.