Preparation of highly conjugated water-dispersible graphene–butyric acid for the enhancement of electron transfer within polyamic acid–benzoxazole: Potential applications in electrochemical sensing

Abstract

To break through the long time and complex procedures for the preparation of highly conjugated reduced graphene oxide (r-GO) in developing electrochemical sensor, a time-saving and simple method is investigated in this study. One novel step of the exfoliated accompanying carboxylated graphene sheet from pristine is achieved via Friedel–Crafts acylation. By electrophilic aromatic substitution, the succinic anhydride ring is opened and attaches covalently to the graphene sheet (Gs) to form exfoliated graphene with grafted 1-one-butyric acid (Gs–BA). The grafting chain converts anions in aqueous solution to maintain Gs–BA in a stable dispersion and noticeably decreases the π–π stacking of the exfoliated Gs during the drying process. The analytical results of the absorption spectroscopy demonstrate that the conjugation of Gs–BA is not significantly destroyed by this chemical modification; Gs–BA retains the Gs electrical properties favorable for developing electrochemical sensors. When polyamic acid-benzoxazole (PAA–BO), a hydrogen peroxide (H2O2)-sensitive probe, hybridizes with Gs–BA to form Gs–BA–PAA–BO, the electron transfer rate relating to the response time improves markedly from 1.09s−1 to 38.8s−1. Additionally, it offers a high performance for H2O2 sensing in terms of sensitivity and response time, making this method applicable for developing glucose and choline biosensors.