Highly sensitive detection of chromium (VI) by photoelectrochemical sensor under visible light based on Bi SPR-promoted BiPO4/BiOI heterojunction

In this work, Bi surface plasmon resonance (SPR)-promoted BiPO4/BiOI heterostructures (Bi-BPI) are synthesized through a one-step hydrothermal method. The structure and morphology have been measured by a series of physical characterizations. Furthermore, the photoelectrochemical (PEC) experiments show that the PEC properties of BiPO4/BiOI are higher than those of pure BiPO4 and BiOI, while BiPO4/BiOI-6 % has the best PEC performance. At the same time, it is found that Bi metal could improve the PEC properties of BiPO4/BiOI-6 %, and that 0.05-Bi-BiPO4/BiOI-6 % has the highest performance among all materials. Ultraviolet-visible diffuse reflection spectra (DRS) and photoluminescence (PL) also prove that 0.05-Bi-BiPO4/BiOI-6 % features excellent visible light absorption and a lower electron recombination rate than the other composites. Therefore, PEC sensors based on 0.05-Bi-BiPO4/BiOI-6 % have been fabricated for the detection of hexavalent chromium (Cr (VI)). They exhibit a wide linear range from 0.5-180 mu M with high stability for sensing Cr (VI). Thus, the PEC sensor has a great potential application in Cr (VI) detection.