Rational design of a sandwiched structure Ni(OH)2 nanohybrid sustained by amino-functionalized graphene quantum dots for outstanding capacitance

The rational structure design of nanohybrids plays a vital role in the supercapacitor performance of electrode materials . Herein, a novel sandwiched structure based on Ni(OH) 2 and amino-functionalized graphene quantum dots (Ni(OH) 2 /af-GQDs) is prepared via a facile green strategy. The layered Ni(OH) 2 nanosheets are spaced by amino groups from af-GQDs to afford a sandwiched configuration with an enlarged pore diameter of 1.8 nm, which leads to the decrease of random aggregation of Ni(OH) 2 nanosheets and dramatically facilitates the ion transport, thus contributing to the increased surface area and improved electrochemical capacitance . Besides, the introduction of af-GQDs leads to enhanced electrical conductivity and better cycling stability as well as contributing additional electrochemical double-layer capacitance, resulting in an outstanding specific capacitance of 2653 F g −1 at 1 A g −1 . An asymmetric supercapacitor (ASC) based on Ni(OH) 2 /af-GQDs and electrochemical-exfoliated graphene (EG) is assembled, exhibiting a wide potential window range, a high energy density , and an excellent cycling stability with 90.15% capacitance retention. These results definitely demonstrate the great potential of Ni(OH) 2 -based hybrid materials in the development of high-performance supercapacitors .