A cathodic photovoltammetric sensor for chloramphenicol based on BiOI and graphene nanocomposites

A visible light-activated photocathode fabricated with p-type semiconductor bismuth oxyiodide (BiOI) and graphene (G) was employed to investigate the photovoltammetric behavior of chloramphenicol (CAP). The result indicated that the voltammetric reduction peak of CAP increased to a limiting current platform under photo-irradiation, owing to photoelectrocatalytic reduction of CAP on the BiOI-G photocathode. As a result, the cathodic photovoltammogram became sigmoidal in shape. Furthermore, the influences of graphene content in BiOI-G composites, scan rate and light intensity on the photovoltammetric behavior of CAP on the BiOI-G photocathode were systematically investigated. Based on such a BiOI-G electrode, a cathodic photovoltammetric sensor for CAP was proposed, which exhibited a current response linearly proportional to CAP concentration in the range of 0.5-50 mu mol L-1, with a detection limit (3S/N) of 0.14 mu mol L-1. Moreover, the photovoltammetric sensor displayed good reproducibility and high stability. The applicability of the proposed sensor was demonstrated by determining CAP in eye drop and environmental water samples.