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A new,highly sensitive bifunctional electrochemical sensor for the simultaneous determination of pentachlorophenol (PCP) and copper ions (Cu2+) has been developed,where organic-inorganic hybrid ultrathin films were fabricated by alternate assembly of humic acid (HA) and exfoliated Mg-Al-layered double hydroxide (LDH) nanosheets onto ITO substrates via a layer-by-layer (LBL) approach.The multilayer films were then characterized by means of UV-Vis spectrometry,scanning electron microscopy (SEM),and atomic force microscope (AFM).These films were found to have a relatively smooth surface with almost equal amounts of HA incorporated in each cycle.Its electrochemical performance was systematically investigated.Our results demonstrate that such a newly designed (LDH/HA)n multilayer films,combining the individual properties of HA (dual recognition ability for organic herbicides and metal ions) together with LDH nanosheets (a rigid inorganic matrix),can be applied to the simultaneous analysis of PCP and Cu(Ⅱ) without interference from each other.The LBL assembled nanoarchitectures were further investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR),which provides insight in the possible mechanism for uptake of PCP and Cu2+ ions.Under the optimized conditions,the detection limit was found to be as low as 1 nM PCP,well below the guideline value of PCP in drinking water (3.7 nM) set by the United States Environmental Protection Agency (U.S.EPA),and 2 nM Cu2+,much below the guideline value (2.0 mg/L ~ 31.2 nM) from the World Health Organization (WHO),respectively.