The sluggish kinetics and four electron oxidation process of oxygen evolution reaction (OER) limit the widespread application of electrochemical water splitting. Recently, NiFe-layered double hydroxide (NiFe LDH) has shown great potential to boost the OER process. However, limited active sites and poor conductivity severely hinder the further improvements on OER performance. Herein, oxygen vacancy-rich hierarchical NiFe LDH (v-NiFe LDH) microtubes assembled by two dimensional (2D) nanosheets were synthesized via a template-assisted strategy. The plentiful oxygen vacancies (VO) could efficiently promote the intrinsic conductivity of the obtained LDH. Meanwhile, featured with hierarchical microtubes and 2D nanosheets, the as-prepared electrocatalyst exhibits abundant catalytic active sites and excellent structural stability. Benefitting from the defect and morphological engineering, the OER activity of v-NiFe LDH has obviously enhanced, with an ultralow overpotential of 195 mV at 10 mA cm-2 and a low Tafel slope of 47.9 mV dec-1, as well as long-term stability at 10 mA cm-2. In addition, theoretical calculations further elucidate that Fe site is the primary active site in v-NiFe LDH and VO can enhance conductivity and accelerate OER kinetic process through decreasing the bandgap of NiFe LDH, and reaction energy of rate-determining step.

Boosting oxygen evolution activity of NiFe-LDH enabled by oxygen vacancy and morphological engineering

ACS Spring 2022

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