Construction of crystalline/amorphous NiP/FePO/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 NiP/amorphous FePO heterostructure (NiP/FePO/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 NiP/FePO/RGO heterostructure exhibits outstanding OER performance in alkaline solutions with overpotentials of 291, 367, and 421 mV at 100, 500, and 1000 mA cm, respectively. Furthermore, the electrolytic cell based on Pt/C and NiP/FePO/RGO can derive 100, 500, and 1000 mA cm at voltages of 1.551, 1.667, and 1.764 V, respectively. Besides, the electrolytic cell also operates stably at 200 mA cm 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.