Facile Spray-Pyrolysis Synthesis of Yolk-Shell Earth-Abundant Elemental Nickel-Iron-Based Nanohybrid Electrocatalysts for Full Water Splitting.

The development of high-activity electrocatalysts for water splitting that comprise only inexpensive, earth-abundant elements is critical but remains a daunting challenge. In this work, yolk-shell Ni Fe/Ni FeN was prepared by a spray-pyrolysis technique, which could be scaleable. The yolk-shell Ni Fe/Ni FeN presents excellent catalytic activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) with overpotentials of 268 and 166 mV at 10 mA cm , respectively, and bears a prominent electrochemical durability. Overall water splitting with an electrolyzer containing the yolk-shell Ni Fe/Ni FeN as the cathode and anode only requires a cell voltage of 1.62 V to reach a current density of 10 mA cm . The present research not only introduces a new route for the synthesis of advanced functional electrocatalysts for overall water splitting but also sheds light on their potential commercial applications.