Engineering core-shell hollow-sphere FeO@FeP@nitrogen-doped-carbon as an advanced bi-functional electrocatalyst for highly-efficient water splitting.

Given the rapidly increasing energy demand and environmental pollution, to achieve energy conservation and emission reduction, hydrogen production has emerged as a promising alternative to traditional fossil fuels because of its high gravimetric energy density, and renewable and environmentally friendly characteristics. Herein, a core-shell hollow-sphere FeO@FeP@nitrogen-doped-carbon (labeled as H-FeO@FeP@NC) with a dual-interface, novel morphology, and superior conductivity is prepared as an advanced bi-functional electrocatalyst for electrochemical overall water splitting using a collaborative strategy comprising of facile self-assembly and phosphating. The prepared catalyst exhibits superior electrocatalytic activity compared to H-FeO@NC and H-FeO for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Additionally, the overpotential of H-FeO@FeP@NC for OER/HER (258/165 mV at 10 mA/cm) is significantly lower than those of H-FeO@NC (274/209 mV) and H-FeO (287/213 mV) at 10 mA/cm. Meanwhile, the as-synthesized H-FeO@FeP@NC, as an electrode pair, displays a low cell voltage of 1.69 V at 10 mA/cm and excellent stability after 100 h, indicating its practical application for overall water splitting. This work presents a practical and economical strategy toward the fabrication of catalyst for efficient water splitting and fuel cell.