Ultrathin Fe2O3 nanosheet-enhanced molecularly imprinted photoelectrochemical sensor for ultrasensitive detection of imidacloprid pesticide

Herein, a novel molecularly imprinted photoelectrochemical (MIP-PEC) sensor was fabricated through integrating the ultrathin nanosheets of Fe₂O₃ (Fe₂O₃ NSs) with molecular imprinting technology for the ultrasensitive detection of imidacloprid (IMD). Impressively, the two-dimensional Fe₂O₃ NSs was synthesized on an indium‑tin oxide (ITO) substrate by electrodeposition. Benefiting from its narrow bandgap and large specific surface area, the photogenerated charge separation efficiency of Fe₂O₃ NSs (∼ 600 μA) was remarkably enhanced compared to that of the commercial Fe₂O₃ nanoparticles (∼150 μA), which significantly improved the sensitivity of the developed MIP-PEC sensor. Furthermore, the electropolymerization technique was used to form a molecularly imprinted polymer film of IMD on the surface of Fe₂O₃ NSs/ITO, substantially increased the detection selectivity of the proposed sensor. As a result, the designed MIP-PEC sensor successfully achieved ultrasensitive and specific as well as reliable detection of IMD with a broad linear response (5 nM ∼ 120 μM), low detection limit (1.02 nM) and long storage time (the signal only decreased by 5.03 % after 4 weeks of storage). The recoveries and relative standard deviation (RSD) for the determination of IMD in fruits and environmental water samples by the obtained MIP-PEC were in the range of 92.0 % ∼ 108.0 % and 3.2 % ∼ 4.9 % respectively, validating its field-applicability. Obviously, this work established a novel paradigm for synergistic enhancement of the analysis performance of PEC through integration of the advanced photosensitive materials with molecular imprinting technology.