Inherent Oxygen Vacancies Boost Surface Reconstruction of Ultrathin Ni-Fe Layered-Double-Hydroxides toward Efficient Electrocatalytic Oxygen Evolution

Unraveling structure-related reconstruction during oxygen evolution reaction (OER) and its correlation with intrinsic electrocatalytic activity is of great significance for designing better catalysts but unfortunately remains elusive. Herein, ultrathin Ni-Fe layered-double-hydroxides (LDH) with inherent oxygen vacancies (VO) are successfully fabricated via coprecipitation under a controlled manner, which accomplish a quite low overpotential of 230 mV at 10 mA cm(-2) in 1.0 M KOH and perform among the best of recently reported nonprecious electrocatalysts. During the OER, inherent VO is experimentally and theoretically evidenced to boost surface reconstruction and the operando formation of p-n interfaces (i.e., gamma-Ni-Fe LDH/alpha-Ni-Fe LDH) via deprotonation. On such reconstructed interfaces, the VO in both surface gamma-Ni-Fe LDH and bulk alpha-Ni-Fe LDH can alter the electron densities of metal sites and subsequently optimize the free energies of a multistep OER pathway, which accounts for the boosted OER activity and, more importantly, identifies the correlation of electrocatalysis with both the catalyst surface and bulk.

Automated summary

The ultrathin Ni-Fe layered-double-hydroxides (LDH) with inherent oxygen vacancies (VO) were successfully fabricated via coprecipitation, achieving low overpotential during oxygen evolution reaction (OER) in potassium hydroxide solution. The presence of VO was experimentally and theoretically proven to boost surface reconstruction and enhance OER activity, highlighting the correlation between electrocatalysis and both the catalyst's surface and bulk properties.