Metal–Organic Framework-Derived Hierarchical (Co,Ni)Se₂@NiFe LDH Hollow Nanocages for Enhanced Oxygen Evolution

Abstract

High-efficient electrocatalysts are crucial for fuel cell applications; however, the whole cell performance is generally restricted by the anodic part because of the sluggish kinetics involved in the oxygen evolution reaction (OER) process. Herein, a hierarchical hollow (Co,Ni)Se₂@NiFe layered double hydroxide (LDH) nanocage was synthesized by deriving from the metal-organic framework (MOF) of ZIF-67. Concretely, it involves first fabrication of hollow rhombic (Co,Ni)Se₂ nanocages and then deposition of NiFe LDH nanosheets on the surface of nanocages. Notably, the incorporation of Ni into Co-based ZIF-67 (via ion-exchange) could tail the atomic arrangement of the MOF, exposing more additional active sites in the following selenization treatment. The as-synthesized (Co,Ni)Se₂@NiFe LDH demonstrates splendid OER performance with a small overpotential of 277 mV (to launch a current density of 10 mA cm^-2), a small Tafel slope of 75 mV dec^-1, and robust durability (a slight stability decay of 5.1% after 17 h of continuous test), not only surpassing the commercial RuO₂ but also being comparable/superior to most reported nonprevious metal-based catalysts. Upon analysis, the outstanding OER performance is attributed to the optimized adsorption/desorption nature of iron and nickel/cobalt toward the oxygenated species and partial delocalization of spin status at the interface via the bridging O^2-. This work represents a solid step toward exploration of advanced catalysts with deliberate experimental design and/or atom tailoring.