Photocurrent determination ascorbic acid using an n-silicon electrode modified by platinum and cobalt hexacyanoferrate films

By depositing a film of cobalt hexacyanoferrate (CoHCF) on silicon electrode coated by a platinum layer, a novel photoelectrochemical sensor for the detection of ascorbic acid (AA) has been developed. The stable film of CoHCF was electrochemically deposited onto a phosphorus heavy doped silicon (n+-Si) with 9 μm epitaxial layer (n–n+-Si) wafers coated with about 40 nm platinum layer (Pt/n–n+-Si). Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD) and cyclic voltammetry (CV) were used to characterize the CoHCF film on the Pt/n–n+-Si electrode. The CoHCF modified Pt/n–n+-Si electrode has been used for determination of AA with a two-electrode cell in absence of reference electrode by photocurrent measurement at a zero bias. The composite modified electrode demonstrated good photocurrent responses by adding different concentrations of AA with a good stability. The linear range for the detection of AA was 1.0 × 10−6 to 1.0 × 10−3 M, with a detection limit (S/N = 3) of 1.0 × 10−6 M. This provides a facile way of detecting AA and succeeds in averting from inconvenient reference electrode.