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A micro electrochemical sensor based on bismuth-modified mesoporous carbon for hexavalent chromium detection

In this paper we report a micro electrochemical sensor to detect trace level hexavalent chromium by adsorptive stripping voltammetry (AdSV) using bismuth-modified directly prototyped mesoporous carbon electrode (Bi/MCE). Trivalent chromium ions reduced from hexavalent chromium ions near the electrode form chelates in the solution. The chelates tend to adsorb and preconcentrate on the surface of the electrode, which will greatly enhance the stripping signal. Mesoporous carbon electrode provides large surface area for adsorption and can be directly prototyped on the silicon substrate thus suitable for batch fabrication. Meanwhile, bismuth film decorated into the carbon frame contributes to low background noise and well-defined peaks. The device shows good a performance, a detection limit of 0.05 μg/L and a linear concentration range of 1 to 25 μg/L are achieved, which provide a solution for portable micro sensor to detect trace hexavalent chromium.