Generation of oxygen vacancies in NiFe LDH electrocatalysts by ultrasound for enhancing the activity toward oxygen evolution reaction

Introduction of vacancies is a promising route to enhance the performance of electrocatalysts by tuning the electronic structure and bonding energy. Here, the influence of ultrasound treatment on the O vacancies formation and interlayer spacing in NiFe layered double hydroxide (LDH) was investigated. It is found that the strong ultrasound treatment results in rich O vacancies on the surface of NiFe LDH, which affect the electrocatalysis performance. Besides, the ultrasound treated NiFe LDH electrocatalysts had a reduced thickness with a hexagonal nanosheet morphology and expanded interlayer distance, which could promote the diffusion of reactant and generated gas. When the obtained defect-rich NiFe LDH electrocatalyst prepared by a 10-min ultrasonic treatment was applied to catalyze oxygen evolution reaction (OER), only 194 mV of overpotential was needed to maintain a current density of 10 mA·cm−2.