Built-in electric field-assisted step-scheme heterojunction of carbon nitride-copper oxide for highly selective electrochemical detection of p-nonylphenol

Taking the advantage of the good matching of the valence and conduction bands of carbon nitride (gC(3)N(4)) and copper oxide (CuO), we successfully fabricated a two-dimensional (2D) step-scheme heterojunction of g-C3N4/CuO via hydrothermal and pyrolysis techniques. The potential of applying this heterojunction in a high-performance electrochemical sensor for environmental hormone nonylphenol (NP) detection was investigated. An amperometric analysis resulted in a linear response on the g-C3N4/CuO modified sensor for NP ranges from 3.00 x 10(-8) to 5.12 x 10(-6) mol L-1 with a detection limit (S/N = 3) of 1.20 x 10(-8) mol L-1. This excellent electrochemical performance could be attributed to a built-in electric field effect at the 2D step-scheme heterojunction interface, thereby boosting the interfacial charge transfer and improving the sensitivity of NP detection. The proposed sensor demonstrated a high selectivity for NP even in the presence of several common environmental hormones. This finding can be attributed to the unique electronic structure of NP molecule and its strong interaction with the 2D gC(3)N(4)/CuO step-scheme heterojunction, as verified by density functional theory (DFT) calculations. This work provides new insights about the gradient energy band for fabricating highly-efficient electrochemical sensor, and paves the way for its potential applications in monitoring crucial environmental components. (C) 2020 Elsevier Ltd. All rights reserved.