Laser Synthesis of MOF-Derived Ni@Carbon for High-Performance Pseudocapacitors

Abstract

Although nanosizing of multiphase pseudocapacitive nanomaterials could dramatically improve their electrochemical properties, a proper way to simultaneously control both the size and the phase of the pseudocapacitive materials is still elusive. Herein, we employed a commercial CO2 laser engraver to do the transformation of a metal-organic framework (MOF-74(Ni)) into size-controlled Ni nanoparticles (4-12 nm) in porous carbon. The produced Ni@ carbon hybrid showed the best specific capacitance of 925 F/g with excellent cycling stability when the particle size is 5.5 nm. We found that the highly redoxactive alpha-Ni(OH)(2) is more predominantly formed than the less redox-active beta-Ni(OH)(2) as the particle size becomes smaller. Our results substantiate that various MOFs could be created into high-performance pseudocapacitive materials with the controlled size and phase. It is believed that the laser-based synthesis could also serve as a powerful tool for the discovery of new MOF-derived materials in the field of energy storage and catalysis.