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Gold nanoparticles (GNPs) were deposited directly onto the surface of indium tin oxide (ITO) thin film-coated glass by electrochemical method. It was used as a photoanode in a photoelectrochemical (PEC) cell for sensitive detection of hydroquinone (HQ) at an applied bias potential of 0.15 V vs. saturated calomel electrode. This heterostructure showed dramatically enhanced PEC properties due to the introduction of the Au/ITO interface. Under the irradiation, the marked photocurrent response was observed at the GNPs/ITO photoelectrode compared with bare ITO electrode. The anodic photocurrent could be further largely enhanced by HQ. A new PEC strategy for sensitive detection of HQ at a relative low potential was developed. The linear range for HQ determination was 0.25 to 150 μM, with a detection limit of 0.1 μM. The sensitivity on the GNPs/ITO electrode at the irradiation was ~ 3.3 times higher than that in dark. These results demonstrate that the simple GNPs/ITO electrodes have great potential for PEC analysis application. [ABSTRACT FROM AUTHOR]

Under visible-light irradiation, a cathodic photoelectrochemical (PEC) sensor is presented for highly sensitive determination of Cr(VI) at a potential of −0.25 V (vs SCE). PbS quantum dots (QDs) were capped with mercaptoacetic acid and assembled on the surface of an indium tin oxide (ITO) electrode via the linker poly(diallyl dimethyl ammonium chloride) providing a photoactive sensor. Cr(VI) accepts the photoelectrons generated by the PbS QDs. This promotes the separation of electron holes and enhances the cathodic photocurrent generated by a 470-nm LED. The sensor has 10 pM detection limit and a linear working range from 0.02 nM to 2 μM of chromate. The method was successfully applied to the determination of Cr(VI) and total chromium in spiked environmental water samples.Schematic illustration of the photocurrent enhancement response of ITO/PbS toward chromium(VI). In the presence of Cr(VI) (red line), Cr(VI) accepts the photoelectrons generated by the PbS QDs under 470-nm LED irradiation, resulting in improved photocurrent of ITO/PbS. [ABSTRACT FROM AUTHOR]