Signal quenching photoelectrochemical sensors have attracted extensive research interests due to outstanding performance and simplicity in realization. This work proposes a photoelectrochemical sensor with photocurrent polarity-switchable property for highly selective and sensitive detection of trace hexavalent chromium (Cr(VI)) ion. Layer-by-layer self-assembled graphene intercalation layer and drop-coated TiO2 nanocrystalline film are successively deposited onto patterned Au/SiO2/Si electrodes. By facilitating the photon-excited electron-hole pair separation, graphene significantly enhances the intensity and stability of the device photocurrent. Coupled with light-sensitive quercetin and its specific interaction with Cr(VI), such sensors can selectively switch the photocurrent polarity from anodic to cathodic with increasing Cr(VI) concentration, resulting in a large sensing range from 1.4 ppb to 2592.3 ppb, with a low detection limit of 0.44 ppb. Featured by the facile fabrication process, low-cost materials, good selectivity, and stable photocurrent output, this sensor shows promising potential applications to on-site environment monitoring.
Bibliographical noteFunding Information:
Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under Award Number ECCS-1542202 .
© 2020 Elsevier B.V.
- Charge transport
- Hexavalent chromium
- Photocurrent polarity
- Photoelectrochemical sensing
- Titanium dioxide