Facile fabrication of chitosan–calcium carbonate nanowall arrays and their use as a sensitive non-enzymatic organophosphate pesticide sensor

Abstract

Novel nanowall arrays of CaCO₃–chitosan (CaCO₃–chi) were deposited onto a cathodic substrate by a facile one-step electrodeposition approach. Results demonstrate that chitosan plays an important role in the formation of nanowall arrays. Freestanding well-aligned CaCO₃–chi nanowall arrays were observed to be uniformly distributed over the whole substrate with a lateral dimension in the micrometre size and an average pore size of ∼400 nm. The as-formed CaCO₃–chi nanowall arrays featuring interlaced porous network architecture, large surface area, and open boundaries, are highly efficient in the capture of organophosphate pesticides (OPs). Combined with stripping voltammetry, a highly sensitive non-enzymatic OPs sensor was fabricated using the prepared CaCO₃–chi nanowall arrays for solid phase extraction (SPE). The detection limit for methyl parathion (MP) in aqueous solutions was determined to be 0.8 ng mL⁻¹ (S/N = 3). The resulting sensor made of novel CaCO₃–chi nanowall arrays exhibits good reproducibility and acceptable stability. This work not only provides a facile and effective route for the preparation of CaCO₃–chi nanowall arrays, but also offers a new promising protocol for OPs analysis.