Liquid phase high shear exfoliated few-layered graphene for highly sensitive ascorbic acid electrochemical sensors

Electrochemical sensors based on graphene have gained importance owing to their high selectivity and sensitivity arising from the high surface area and electrocatalytic activity of graphene based nanomaterials. While significant amount of work has been carried out on graphene synthesis, lesser attention has been paid to synthesis of graphene suited for electrochemical sensing applications. This work demonstrates the synthesis of graphene by using a liquid phase high shear exfoliation (LP-HSE) method. Use of appropriate dispersing and antifoaming agents helped in obtaining a high-quality graphene colloidal suspension in water. Later, the dispersing and antifoaming agents were washed away to get exfoliated graphene suited for electrochemical sensing as confirmed by electrocatalytic activity measurements. The potential usage of exfoliated graphene in electrochemical sensors was confirmed by evaluating the performance of exfoliated graphene for ascorbic acid sensing. Linear sweep voltammetry (LSV) and amperometry techniques were used for ascorbic acid sensing. The sensor based on exfoliated graphene was highly selective and sensitive toward ascorbic acid (AA) oxidation, and the limit of detection (LOD) of fabricated sensors was 1.8 μM. The interference study confirmed that the fabricated sensors are highly selective. The precise determination of AA in vitamin C supplements revealed the potential usage of exfoliated graphene in the real-time determination of AA. Electrochemical activity of high shear exfoliated graphene enhanced owing to high surface area and defects formed during exfoliation. Selective oxidation of ascorbic acid (AA) by exfoliated graphene led to highly selective AA electrochemical sensors.