Construction of crystalline/amorphous Ni₂P/FePO_x/graphene heterostructure by microwave irradiation for efficient oxygen evolution

The rational design of highly efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts is crucial for hydrogen production through electrocatalytic water splitting. Although the crystalline/amorphous heterostructure shows great potential in enhancing OER activity, its fabrication presents significantly greater challenges compared to that of crystalline/crystalline heterostructures. Herein, a microwave irradiation strategy is developed to construct reduced graphene oxide supported crystalline Ni₂P/amorphous FePO_x heterostructure (Ni₂P/FePO_x/RGO) as an efficient OER electrocatalyst. The formation of this heterostructure can induce electron redistribution, optimize adsorption capability for intermediates, provide abundant active sites and promote the reconstruction to form highly active oxyhydroxides, thereby improving the OER activity of the electrocatalyst. Consequently, the Ni₂P/FePO_x/RGO heterostructure exhibits outstanding OER performance in alkaline solutions with overpotentials of 291, 367, and 421 mV at 100, 500, and 1000 mA cm^-2, respectively. Furthermore, the electrolytic cell based on Pt/C and Ni₂P/FePO_x/RGO can derive 100, 500, and 1000 mA cm^-2 at voltages of 1.551, 1.667, and 1.764 V, respectively. Besides, the electrolytic cell also operates stably at 200 mA cm^-2 for over 150 h. This work presents a novel approach for constructing crystalline/amorphous heterostructured electrocatalysts and provides valuable insight into designing high-efficiency OER electrocatalysts.