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To develop feasible probes for heavy metal ions has been considered as one of the most important research topics, due to the significance in monitoring and evaluating the toxicity of environmental water system, especially for the drinking water. This work provided a probe for Pb(II) ion detection in purified drinking water. Nickel hexacyanoferrate (NiHCF) films were prepared by vacuum evaporating nickel fine wire and transforming in a potassium ferricyanide solution on the front surface of platinum coated n-silicon. The transformed NiHCF film shows a reversible insertion electrochemistry and possesses electrocatalytic activity under illumination. The NiHCF-modified electrode was used as photoelectrode and dihydroxybenzene as photocurrent mediators to make up photoelectrochemical (PEC) sensor for Pb(II) ion detection in purified drinking water based on a two-electrode cell in absence of reference electrode and operated at zero working voltage. We have investigated the effects of Pb(II) ions on the photocurrent of hydroquinone or catechol in the purified water. The assay demonstrated good photocurrent responses by adding different concentrations of Pb(II) ion into purified drinking water with a linear range of 20-1560 nM and the limit of determination (based on S/N = 3) is 4.8 nM and 5.3 nM for the presence of hydroquinone and catechol, respectively. [ABSTRACT FROM AUTHOR]

A platinum (Pt) film coated n-silicon (Pt/n-n-Si) was modified with nickel(II)-potassium hexacyanoferrate (NiHCF)-graphene sheets (GS) hybrid and used as a photo-electrochemical (PEC) sensor for non-enzyme hydrogen peroxide (HO) detection. A NiHCF film was deposited on the surface of GS/Pt/n-n-Si electrode by chemical method. The structure and composition of the NiHCF film was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). PEC behavior of the NiHCF-GS/Pt/n-n-Si electrode was investigated using cyclic voltammetry (CV) under illumination. The modified electrode has been used as PEC sensor for HO detection with a linear range of 2.0 × 10-2.9 × 10 M and a detection limit of 1.0 × 10 M at a signal-to-noise ratio of 3 in a two-electrode cell with a Pt plate as counter electrode. The characteristics of GS layer have been discussed in both the improvement of sensibility and selectivity. [ABSTRACT FROM AUTHOR]

A novel photo-electrochemical and non-enzymatic hydrogen peroxide (HO) sensor was fabricated by electrochemically cathodic plating nickel hydroxide (Ni(OH)) on platinum films coated n-silicon (Pt/n-n-Si electrode). Nickel oxide hydroxide (Ni(OH)-NiOOH) films on the Pt/n-n-Si electrode were formed by cyclic voltammetry in 0.2 M KOH solution. The morphology and composition of Ni(OH)-NiOOH film were characterized via scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. A two-electrode cell based on Ni(OH)-NiOOH/Pt/n-n-Si electrode and a platinum counter has been used for determination of HO in the absence of reference electrode by photocurrent measurement at a zero bias. In these conditions a sensitivity of 96.9 μA mM cm and a linear response range from 0.02 up to 0.16 mM with a determination limit (S/N = 3) of 5.4 μM were achieved in KOH solution at pH 13.3. In addition, the electrode also exhibited superior stability, anti-interference and selectivity. [ABSTRACT FROM AUTHOR]