Operando spectroscopies unveil interfacial FeOOH induced highly reactive β-Ni(Fe)OOH for efficient oxygen evolution

Interfacial engineering is an effective strategy for the design of active oxygen evolution electrode. Yet the intrinsic mechanism of heterogeneous interfaces remains largely unclear for the lack of direct evidence of real active phases. Herein, operando ultraviolet-visible (UV–vis) and Raman spectroscopies were used to probe the surface reconstruction behaviors of [email protected] layered double hydroxides (LDH) hybrid catalysts, which revealed that [email protected] LDH was converted into highly active [email protected] β-Ni(Fe)OOH phases during the OER process. The FeOOH-NiFe LDH interface can promote interfacial charge transfer, delay the Ni oxidation and induce the NiFe LDH phases to highly reactive β-Ni(Fe)OOH. The [email protected] β-Ni(Fe)OOH exhibited excellent OER performance (252 mV at 100 mA cm−2) and a 1.6 times increase (at overpotential of 300 mV) in turnover frequency (TOF) with respect to the active phase γ-Ni(Fe)OOH of NiFe LDH. This work clarifies that ration interface engineering can regulate the generation of highly active phases in the OER process.