Biomimetic three-dimensional multilevel nanoarray electrodes with superaerophobicity as efficient bifunctional catalysts for electrochemical water splitting

The design and preparation of cost-effective and durable catalysts for electrochemical water splitting are significant for the development and application of hydrogen production. Herein, inspired by the underwater superaerophobicity of fish scales, a three-dimensional multilevel nanoarray electrode with superaerophobicity was designed and fabricated by the hydrothermal method to solve the bubble shielding effect in electrochemical reactions. Benefiting from the high specific surface area, superaerophobic properties, and Al doping, the Al-CoS₂ nanosheets (NSs)/nickel foam (NF)-30 exhibits outstanding electrocatalytic activity and superior durability for electrochemical water splitting in 1 M KOH. Significantly, the Al-CoS₂ NSs/NF-30 only required extremely low overpotential of 176 mV for oxygen evolution reaction (OER) to reach a current density of 10 mA·cm^–2. Al-CoS₂ NSs/NF-30 was employed as bifunctional electrode for electrochemical water splitting with a cell voltage of 1.58 V at 10 mA·cm^–2. Meanwhile, Al-CoS₂ NSs/NF-30 exhibited excellent durability (250 h@10 mA·cm^–2 and 50 h@100 mA·cm^–2). The cobalt-based catalyst (Al-CoS₂ NSs/NF-30) with superaerophobicity exhibits excellent performance in activity and durability, and therefore is a promising electrochemical water splitting catalyst.