NiFe Layered Double Hydroxides Grown on a Corrosion-Cell Cathode for Oxygen Evolution Electrocatalysis

For sustainable hydrogen production, electrochemical water splitting is a promising method whose efficiency is limited by its anodic reaction, i.e., the oxygen evolution reaction (OER). One of the best electrocatalysts for the OER is the self-supported nickel-iron layered double hydroxides on iron foam (NiFe-LDH@IF) prepared by corrosion engineering. However, the further development of NiFe-LDH@IF is hampered by a lack of understanding regarding the growth mechanism and the effects of corrosion conditions on the electrocatalytic activity. Herein, the growth mechanism is studied, revealing for the first time that NiFe-LDH@IF is formed by the preferential precipitation of NiFe-LDH on the NiFe-alloy cathode around which the local pH is high due to the reduction of dissolved oxygen. Guided by this growth mechanism, it is found that corrosion conditions mainly affect the electrocatalytic activity of NiFe-LDH@IF via changing the amount of alpha-FeOOH and NiFe-LDH along with the Fe2+-doping level of NiFe-LDH. With the aid of these findings, corrosion conditions are optimized and the prepared NiFe-LDH@IF exhibits the best reported comprehensive electrocatalytic performance. More importantly, the growth mechanism of NiFe-LDH@IF can be generalized to various self-supported LDH on different substrates prepared by corrosion engineering.