Copper ions (Cu) is an indispensable trace element in the process of metabolism and intake of excessive Cu may lead to fatal diseases such as Alzheimer’s disease. It is highly demanding to develop a sensitive, selective and convenient method for Cu detection. In this work, thin-layer structured polyethyleneimine (PEI) decorated black phosphorus (BP) nanocomposite is one-step synthesized for an electrochemical sensor toward direct detection of Cu. This sensor achieves a wide detection range of 0.25-177 μM, a low detection limit of 0.02 μM much below the Environmental Protection Agency (EPA) maximum contaminant levels for drinking water (20 μM for Cu), and much faster response (1.5 s response time) and simpler operation than the conventional tedious anodic stripping voltammetry, ranking one of the best among all reported Cu sensor. The great sensing enhancement is mainly due to a synergistic effect of BP and PEI of the composite, of which the former offers the reactivity while the latter splits the thick BP to thin-layer structured PEI-BP composite for larger reaction area. Meanwhile, a flexible sensor has been successfully fabricated and applied in detecting of Cu in real samples of river, confirming the application feasibility of PEI-BP sensor in water environment control.
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