Surface Amorphization: A Simple and Effective Strategy toward Boosting the Electrocatalytic Activity for Alkaline Water Oxidation

It is urgent but still remains challenging to boost the alkaline water oxidation activity of transition metal oxide electrocatalysts for applications. In this work, we report our recent finding that surface introduction of an amorphous nickel–borate (Ni-Bi) layer on a nickel oxide (NiO) nanosheet array on carbon cloth (NiO/CC) can greatly enhance its electrochemical water oxidation activity under alkaline conditions. In a 1.0 M KOH solution, the resulting core–shell NiO@Ni-Bi/CC shows superior electrochemical catalytic activity of only 290 mV to drive 10 mA cm–2, 100 mV less than that for NiO/CC. Meanwhile, this catalyst electrode shows great long-term durability for at least 25 h. The high activity can be ascribed to the Ni-Bi layer on NiO promoting NiOOH generation as the active species. This study provides us an abundant water oxidation catalyst in an alkaline water electrolysis device for high-performance, durable electrolytic hydrogen production.