Abstract
Hexavalent chromium, namely, Cr(VI), is a significant threat to ecological and food safety. Current detection methods are not sensitive to Cr(VI). A photoelectrochemical (PEC) sensor based on bismuth vanadate (BiVO4) was developed for sensitive detection of Cr(VI). First, BiVO4-X (X: the pH of the reaction precursor solution) was synthesized using a facile surfactant-free hydrothermal method. The BiVO4-X morphology was well controlled according to pH values, showing rock-like (X = 1), wrinkled bark-like (X = 4), carnation-like (X = 7), and the collapsed sheet-like morphologies (X = 9, 12). BiVO4-7 exhibited excellent photoelectric performance due to a proper band structure under visible light and a large specific surface area. Then, BiVO4-7 was used to construct a PEC sensor to detect Cr(VI), which was demonstrated to have a low detection limit (10 nM) and wide detection range (2–210 μM). The BiVO4-7 PEC sensor had a stable output signal, as well as excellent reproducibility, repeatability, and selectivity. We used the BiVO4-7 PEC sensor to detect Cr(VI) in real environmental and food samples, resulting in a satisfactory recovery of 90.3–103.0%, as determined by comparison with results obtained using a spectrophotometric method. The BiVO4-7 PEC sensor is promising for practical application to heavy metal detection in the food and environment.
Highlights
The rapid development of industrial manufacturing has made chromium contamination an increasingly significant focus in the environmental monitoring and food industries [1–3]
With a group I classification from the International Agency for Research on Cancer, hexavalent chromium (Cr(VI)) can cause genotoxic tumors, genetic defects, asthma, and allergies and harm the environment by accumulating in the ambient environment and food chains [4–9]
A promising technique is the use of a photoelectrochemical (PEC) sensor, which offers the advantages of being low cost, requiring simple equipment that is easy to operate, and a low background signal [15–19]
Summary
The rapid development of industrial manufacturing has made chromium contamination an increasingly significant focus in the environmental monitoring and food industries [1–3]. Especially for Cr(VI) detection in food and soil samples, is to reduce the sample matrix effect by suitable sample preparation. A water sample is a typical matrix for Cr(VI) detection by a PEC sensor. A hydrothermal method without surfactants (SDBS, CTAB, PVP, DA, OL, OA, etc.) was used to synthesize BiVO4 with a controlled morphology. The PEC sensor based on the optimized BiVO4 with a carnation-like morphology was used for Cr(VI) detection in soil, rice, peanut, and water. A simple sample preparation protocol was developed to reduce the complex matrix effect. This PEC sensor can be extensively applied to monitor environmental and food safety. The chemicals and reagents used in this study are listed in the Supplementary Material
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