N-doped graphene quantum dots embedded in BiOBr nanosheets as hybrid thin film electrode for quantitative photoelectrochemical detection paracetamol

A facile strategy of electrophoretic deposition has been employed to fabricate a thin film photoelectrochemical (PEC) sensor of functionalized N-doped graphene quantum dots (F-NGQDs) embedded in BiOBr nanosheets, which were prepared by a two-step hydrothermal method, loaded onto indium -tin-oxide coated glass substrate (F-NGQDs/BiOBr/ITO). Electrophoretic deposition provides a mild and environmentally friendly method for PEC film formation. Multiple techniques were applied to investigate the electronic, optical properties and structure of F-NGQDs/BiOBr thin films photoelectrodes. It was found that F-NGQDs/BiOBr thin films with NGQDs/BiOBr heterojunction possess an enhanced charge transfer and absorption wavelengths under visible light, particularly when compared to pristine F-BiOBr films, thus producing an increase in the observed photocurrent. Sensing performance measurements showed the F-NGQDs/BiOBr/ITO photoelectrode has a higher photoelectric response current to paracetamol, it was used to detect trace paracetamol under visible light irradiation. The sensor exhibited a wide linear range, low detection limit and good sensitivity, given the photoactivity of NGQDs/BiOBr heterojunction. The developed PEC sensor displayed an acute response to paracetamol in a linear range of 0.01 mu M-20.0 mu M with a detection limit of 3.33 nM, under optimal conditions. Here we present evidence that F-NGQDs/BiOBr/ITO photoelectrode is a promising candidate for PEC analysis. (C) 2019 Elsevier Ltd. All rights reserved.