Vacancies-Riched composite of ultrathin NiFe-LDH nanosheets on the etched Prussian blue analogue: An efficient alkaline oxygen evolution electrocatalyst

Oxygen vacancy can significantly improve the intrinsic activities of electrocatalysts towards oxygen evolution reaction (OER). Besides, the 3D hierarchical structure can release more active sites and optimize the adsorption/desorption energy of ∗OOH, ∗O, and ∗OH intermediates during the electrocatalytic process. In this study, the 3D heterostructure of NiFe-layered double hydroxides@etched Prussian blue analogue (NiFe-LDH@E-PBA) is prepared on nickel foam by electrodeposition and alkali etching processes. The alkali etching and the electrodeposition endow NiFe-LDH@E-PBA with abundant oxygen vacancies and plentiful active sites. The synergistic effect between NiFe-LDH and E-PBA offers efficient charge and mass transfer. Density functional theory calculations reveal that the interfacial electron transfer is conducive to the adsorption of OER intermediates. Hence, the catalyst displays outstanding electrocatalytic OER performance with a low overpotential of 263 mV at 100 mA cm −2 , a small Tafel slope of 34.78 mV dec −1 , and robust durability with a stable operation over 50 h at 100 mA cm −2 . NiFe-LDH@E-PBA also demonstrates excellent alkaline overall water-splitting performance by acting as both the anode and the cathode. The cell voltages at current densities of 10 and 100 mA cm −2 are 1.65 and 1.80 V, respectively. This work offers a novel approach for the fabrication of a 3D heterostructure with rich vacancies to enhance the electrocatalytic activity.