Construction of Al-doped FeCoP nanosheet array with superhydrophilic/superaerophobic characteristics as a bifunctional electrocatalyst for activating alkaline overall water splitting

Hydrogen is regarded as “the ultimate clean energy source”, with the virtues of zero pollution, renewability and abundant reserves, which is expected to alleviate problems including global climate change and energy crisis. Designing reasonable methods for synthesizing efficient, inexpensive, and stable electrocatalysts for water splitting is urgently needed. In this study, we construct Al-FeCoP nanosheet array on nickel foam (Al-FeCoP/NF) with superhydrophilic/superaerophobic properties. The superhydrophilic and underwater superaerophobic surface accelerate the electrolyte penetration and bubble dissipation, thereby taking the edge off the “bubble shielding effect”. The electronic structure of the electrocatalyst is tuned through heteroatom doping and phosphorization, which effectively enhances the conductivity of the catalyst. Strikingly, the resulting Al-FeCoP/NF electrode shows remarkable activity in alkaline media, which only requires an overpotential of 121 mV and 215 mV at 10 mA cm⁻² for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. When applied for overall water splitting, the assembled two-electrode electrolyzer only needs a low voltage of 1.56 V to afford a current density of 10 mA cm⁻² and can maintain over 100 h without the obvious activity attenuation, which enhances the overall catalytic activity and represents superior long-term stability. In addition, the abundant wind and solar energy resources are employed to generate electricity directly, which is subsequently convert into green hydrogen by the water electrolysis in laboratory conditions. This work provides a new idea for the manufacture of low-cost, high-activity bifunctional transition-metal phosphide electrocatalyst by element doping for green hydrogen production.