Chemical deposition and exfoliation from liquid crystal template: Nickel/nickel (II) hydroxide nanoflakes electrocatalyst for a non-enzymatic glucose oxidation reaction

Abstract

This work reports the synthesis of nickel/nickel hydroxides nanoflakes (Ni/Ni(OH) 2 -NFs) at room temperature via a novel chemical deposition and exfoliation from a liquid crystal template mixture. The nickel ions dissolved in the interstitial aqueous domain of the Brij®78 hexagonal liquid crystal template were deposited by a reducing agent of sodium borohydride that concurrently reduces the nickel ions and generates extreme hydrogen gas bubbles, that exfoliated the nickel/nickel hydroxide layers. The Ni/Ni(OH) 2 -NFs crystal structure, morphology, and surface area characterizations revealed the formation of semi-crystalline α-Ni(OH) 2 nanoflakes with a thickness of approximately 10 nm and a specific surface area of about 135 m 2 /g. The electrochemical measurements of cyclic voltammetry, chronoamperometry, and impedance analysis showed that the Ni/Ni(OH) 2 -NFs exhibited significant performance for the glucose non-enzymatic oxidation in an alkaline solution in comparison to the bare -nickel hydroxide ( bare -Ni(OH) 2 ) deposited without surfactant. The Ni/Ni(OH) 2 -NFs electrode showed superior glucose oxidation activity over the bare -Ni(OH) 2 catalyst with a sensitivity of 1.078 mA mM −1 cm −2 with a linear concentration dependency range from 0.2 to 60 mM and a detection limit of 0.2 mM (S/N = 3). The enhanced electrochemical active surface area and mesoporosity of the 2D nanoflakes make the Ni/Ni(OH) 2 -NFs a promising catalyst in the application of glucose non-enzymatic sensing.