Construction of Multilayer Non‐Covalently Bonded Cobalt/Iron Hydroxides Planar Heterojunction for Investigating the Effect of Interfacial Contact on the Oxygen Evolution Reaction

Multilayer non‐covalently bonded CoFe hydroxides planar heterostructures were constructed by combining electrochemical deposition with layer by layer assembly to investigate the influence of interfacial contact on the oxygen evolution reaction (OER). The overpotential of Co(OH) 2 /Fe(OH) 3 planar heterostructures with three layers is only 234 mV at 10 mA/cm 2 , which is better than those of single Co or Fe hydroxides and bulk bimetallic CoFe(OH) x . Electrocatalysts characterized by a Co(OH) 2 outer layer exhibit enhanced OER activity and stability in comparison to those featuring an Fe(OH) 3 outer layer. The morphology characterization and mass determination before and after OER demonstrated that the Co(OH) 2 nanosheets can provide a stable resistant structure for the shedding of Fe(OH) 3 nanoparticles, which prevents the loss of Fe species and confers the electrocatalyst with exceptional long‐term stability.