Interfacial potential barrier driven electrochemical detection of Cr^sup 6

3D NiO/polyaniline p-p junction foam was prepared and applied for electrochemical detection of Cr6+. The electrochemical detection using interfacial potential barrier was illustrated and a mature theoretical model was built to demonstrate the mechanism. Electrochemical sensing signals of targets can be revealed by changing the height of potential barrier after specific adsorption. The extra high sensitivity (0.78 μA nM−1) and low detection limit (3.96 × 10−4 nM) of Cr6+ were achieved by applying the p-p junction interfacial potential barrier as driven factors. This work proposes a model to apply the potential barrier for electrochemical detection of metal ions, which can be further developed for a wide range of specific substance detection.