Non‐noble metal Fe2O3@NiO as efficient bifunctional catalysts for water splitting.

The development of non‐noble metal catalysts is crucial for hydrogen production. In this study, electrochemically reconfigurable Fe2O3@NiO‐x composite catalysts were synthesized within tens of seconds using a simple microwave deposition method. Interestingly, Fe2O3@NiO‐5 exhibited a high‐speed and deep surface reconstruction capability, greatly enhancing the hydrogen evolution reaction (HER) activity. DFT calculations also confirmed that the reconstruction process optimized the adsorption energy of H2O and H intermediate to promote HER kinetics. The optimized Fe2O3@NiO‐5 electrode only afforded an overpotential of 295 mV at 10 mA cm−2 and it steadily functioned for 25 h for HER in 1 M KOH. In addition, benefiting from the combination of Fe2O3 and NiO layer during the synthesis process, Fe2O3 and NiO converted into FeOOH and NiOOH, respectively, resulted in the excellent oxygen evolution reaction (OER) activity of Fe2O3@NiO‐5. The as‐prepared Fe2O3@NiO‐5 only required an overpotential of 186 mV at 10 mA cm−2 and exhibited excellent stability for up to 144 h. As a bifunctional catalyst, the Fe2O3@NiO‐5 electrode can deliver a current density of 20 mA cm−2 at a low voltage of 1.78 V with high durability for water splitting. This work can provide a new perspective for constructing advanced non‐noble metal electrode. [ABSTRACT FROM AUTHOR]