Fe2O3 nanoparticles immobilized on N and S codoped C as an efficient multifunctional catalyst for oxygen reduction reaction and overall water electrolysis

Currently, multifunctional electrocatalysts with superior performance are very vital for developing various clean and regenerated energy systems. Herein, an effective multifunctional electrocatalyst comprising Fe₂O₃ nanoparticles immobilized on N and S codoped C has been synthesized via heat-treatment of Fe(II) complex at 800 °C (denoted as Fe₂O₃/NS-C-800). Favorable features including the introduction of maghemite nanoparticles, N/S-codoping effect, and close contact between the Fe₂O₃ nanoparticles and NS-C ender the Fe₂O₃/NS-C-800 with high multifunctional catalytic performance. The onset potential (0.97 V) and half-wave potential (0.81 V) of the Fe₂O₃/NS-C-800 towards oxygen reduction reaction (ORR) are comparable to Pt/C (0.99 and 0.82 V). The Fe₂O₃/NS-C-800 also exhibits high oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity with low OER and HER overpotentials of 0.37 and −0.27 V at 10 mA cm⁻², respectively. In addition, higher ORR, OER and HER stabilities than Pt/C are observed for the Fe₂O₃/NS-C-800. More importantly, the assembled water electrolyzer using the Fe₂O₃/NS-C-800 as the anode and cathode exhibits a high stability at a water electrolysis current density of 10 mA cm⁻². The present study offers a new promising non-noble multifunctional catalyst for future application in renewable energy technologies.