Ethanol-Assisted Ultrafast Quenching of Substrates Realizes Enhanced Oxygen Evolution

The direct growth of nickel-iron layered double hydroxide (NiFe-LDH) through the surface reconstruction of conductive substrates integrates the active phase with the current collector into a single electrode without any other additives and is indeed beneficial for the oxygen evolution reaction (OER). However, in conventional electrode fabrication strategies, the simultaneous regulation of substrate reconstruction and defect-related electronic states in a very short time remains challenging. Here, an ethanol-assisted ultrafast quenching strategy is used to construct self-supported NiFe-LDH nanosheets on an industrial Ni mesh. During rapid quenching, the FeCl3-containing ethanol/water medium promotes Ni-substrate reconstruction and in situ NiFe-LDH nanosheet growth. The ethanol/water environment further regulates the oxygen-vacancy-related electronic structure and modulates the local electronic environments of the Ni and Fe sites. These features jointly lead to an enhanced catalytic effect for the alkaline OER. Remarkably, the resulting electrode requires overpotentials of 258 and 308 mV to reach 10 and 100 mA cm-2, respectively, and exhibits excellent stability. Moreover, this strategy is also applied to other Ni-based substrates. This work offers a simple nonequilibrium approach for designing efficient self-supported OER electrodes.