Zn-triggered synthesis of NiP/NiP microflower arrays for efficient alkaline overall water splitting

Designing a transition metal-based bifunctional electrocatalyst with a unique structure, excellent activity, and good stability for alkaline overall water splitting remains a challenge. Herein, a novel three-dimensional heterogeneous Ni2P/Ni12P5 microflower array (Zn-Ni2P/Ni12P5/NF) grown on nickel foam (NF) substrate was prepared by a Zn2+-triggered phosphating route. The Zn-doping enhances the electronic interaction with Ni and P atoms, and regulates the electronic structure, surface state, and microstructure of the catalyst, which greatly increases the catalytic active site and improves the electrochemical reaction area and electron transfer efficiency of Zn-Ni2P/Ni12P5/NF. The prepared Zn-Ni2P/Ni12P5/NF exhibits excellent HER and OER properties, for HER, high current densities of 500 and 1000 mA/cm2 can be driven with low overpotentials of only 315 and 367 mV in 1 M KOH. For OER, the overpotential is only 414 and 477 mV at industrial current densities of 500 and 1000 mA/cm2. In addition, the current density of 1000 mA/cm2 can be achieved with a voltage of only 2.10 V, and the electrode surface also exhibits hydrophilic (solid-liquid interface) and superaerophobic characteristics that are more conducive to the catalytic reaction. This work provides an effective strategy to prepare HER/OER bifunctional electrocatalysts for large-scale water splitting.