Facile Synthesis of Orientation-Controlled NiCo-LDH Nanosheets on Multilayer Graphene for Supercapacitors

Abstract

The orientation of pseudocapacitive nanosheets on highly conductive carbon substrates governs their electrochemical behavior and ultimately determines supercapacitor performance. Here, we report a nucleation strategy for controlling the orientation of nickel-cobalt layered double hydroxide (NiCo-LDH) nanosheets on multilayer graphene (MLG). The approach leverages ethylenediaminetetraacetic acid (EDTA) as a chelating agent to moderate crystallization, combined with temperature control to dictate seed density. A low temperature of 0°C induces sparse nucleation seeds, yielding NiCo-LDH nanosheets parallel to the MLG surface. Increasing the nucleation temperature promotes denser nucleation seeds, progressively elevating the angle between the nanosheet and MLG, ultimately achieving nearly vertical alignment at 90°C. When employed as supercapacitor cathodes, these orientation-controlled composites exhibit excellent rate capability and alignment-dependent electrochemical performance.

Graphical Abstract

This study achieves control of NiCo-LDH nanosheet orientation, from parallel to vertical configurations, on multilayer graphene (MLG) through tailored nucleation. This controlled growth yields an obvious morphology-performance relationship—vertically aligned nanosheets maximize ion accessibility for enhanced capacitance, while parallel configurations ensure structural stability.