Hierarchical trimetallic layered double hydroxide nanosheets derived from 2D metal-organic frameworks for enhanced oxygen evolution reaction

摘要

Fabrication of monolayer LDHs nanosheets with high electrocatalytic activity and durability is still challenging. In this study, a series of hierarchical trimetallic LDHs composed of monolayer nanosheets are fabricated from oxalate metal-organic frameworks (MOFs) grown on copper foil by in-situ conformal transformation. LDHs maintain the octahedron morphology of MOFs, which is composed of ultrathin nanosheets. TEM and AFM images reveal that the thickness of the LDHs nanosheet approaches to 1 nm. These hierarchical trimetallic LDHs exhibit excellent activity and stability towards oxygen evolution reaction (OER) in alkaline electrolytes. Among them, FeCo0.5Ni0.5-LDH show the smallest overpotential of 248 mV at a current density of 10 mA cm(-2) with a small Tafel slope of 38 mV dec(-1), which is competitive to most reported catalysts. In-situ Raman and X-band electron paramagnetic resonance measurements reveal that the OER active sites are Ni atoms.