Flame-Engraved Nickel-Iron Layered Double Hydroxide Nanosheets for Boosting Oxygen Evolution Reactivity

Introducing oxygen vacancies to metal oxide materials would improve their catalytic activity but usually needs reductive reagents (e.g., H-2) and high temperatures (e.g., >600 degrees C), which is unsafe, complex, and time consuming. Herein, a fast (30 s) and facile (operated at ambient conditions) flame-engraved method is used to introduce abundant oxygen vacancies and well-defined hexagonal cavities with (110) edges to nickel-iron layered double hydroxides (NiFe-LDH). Abundant oxygen vacancies, lower coordination numbers, and electron-rich structures of Ni and Fe sites emerge in the flame-engraved NiFe-LDH array electrode, leading to its onset potential as low as 1.40 V (vs reversible hydrogen electrode) for oxygen evolution reaction. This highlights the importance and convenience of flame-engraving method in preparing metal hydroxides with abundant oxygen vacancies, which can be used as efficient electrochemical catalysts.