Ultrathin metal–organic framework hybrid nanosheets enabled active oxygen evolution electrocatalysis in alkaline media

Abstract

• Ultrathin MOF hybrid nanosheets with 2.5 nm thickness were synthesized. • They demonstrate excellent OER activity and durability in alkaline media. • Their OER performance is associated to their unique structural and compositional properties. Metal-organic framework (MOF) with unique structural ordering and compositional flexibility has inspired tremendous interest for electrocatalysis. However, it remains elusive as how to adjust its structure and composition for enhanced electrocatalytic performance. In this paper we report the synthesis of 2.5 nm thick MOF hybrid nanosheets and their excellent electrocatalytic performance toward oxygen evolution reaction (OER). These nanosheets were composed of sulfide cluster-doped ultrathin Ni/Fe bimetallic MIL-53 MOF, and show excellent alkaline OER activity and durability; it delivers OER current of 50 and 100 mA cm −2 at 234 and 256 mV overpotential, respectively. Its activity does not fade after 70 h operation at 50 mA cm −2 . The ultrathin nanosheet structure enables exposing of abundant coordinately unsaturated surface active sites, and the doped sulfide clusters optimize the electronic structure and enhance the electrical conductivity of the nanosheets.