In-situ integration of nickel-iron Prussian blue analog heterostructure on Ni foam by chemical corrosion and partial conversion for oxygen evolution reaction

Pristine Prussian-blue analogues (PBAs) are deemed to be very promising candidates for efficient catalysis. However, few reports are available on exploring the PBAs-based materials in the field of water oxidation due to their poor conductivity and limited catalysis performance. Herein, a chemical corrosion strategy is proposed to in-situ hierarchically deposit Ni-Fe Prussian-blue analogue (NiFePBA) on Ni foam (NF) to fabricate the 3D self-supported electrode. Followed by acid etching and calcination at low temperature, this semisacrificial template derives a core-shell heterojunction, in which the undecomposed NiFePBA serves as the core and the surficial NiFe2O4 acts as the shell. This well-designed composite delivers a prominent performance for oxygen evolution reaction (OER) with a low overpotential of 244 mV at the current density of 10 mA·cm−2 and 304 mV at 100 mA·cm−2. This hierarchical structure provides abundant active sites, facilitates electrolyte infiltration and promotes fast charge and mass transportation, which all contribute to the remarkable activity towards water oxidation. Additionally, the chemical corrosion strategy in this work opens a promising avenue to deposit PBAs or PBAs derivatives on the metal substrates to fabricate multiple 3D self-supported electrodes.