Spinel-type high-entropy oxide nanotubes for efficient oxygen evolution reaction

Abstract

Oxygen evolution reaction (OER) involved 4-electron transfers is generally considered as the bottleneck for electrocatalytic water splitting. High-entropy oxides (HEO) show promising potential for OER due to their flexible structures and tunable compositions. Herein, we report a facile strategy to synthesize spinel-type (FeCoNiMnCr)3O4 HEO nanotubes (NTs) with unique hollow structures by combining electrospinning process and calcination treatment. The (FeCoNiMnCr)3O4 HEO NTs prepared at 400 °C exhibit the low overpotential of 353 mV at 50 mA cm−2 and small Tafel slope of 55.6 mV dec−1 in 1 M KOH electrolyte. The three-dimensional (3D) nanofiber-based architecture ensure the superior stability, as evidenced by the stable current density under continuous OER process for more than 60 h. Meanwhile, the hollow structure provides abundant exposed active sites, which could significantly improve the OER activity. This work provides new design of low-cost and high-efficient HEO with ensemble active sites for OER.