Specific detection against diazinon by using Schottky junction driven photoelectrochemical aptasensor

As a widely used insecticide, diazinon (DIA) is easily hydrolyzed into highly toxic tetraethyl thiophosphate in water, posing significant long-term risks to both aquatic ecosystems and public health. A sensitive photoelectrochemical (PEC) aptasensor was developed by integrating Mo₂N nanoparticles with g-C₃N₄ (Mo₂N/g-C₃N₄) to function as an electron acceptor for DIA detection. The combination of high conductivity and wide spectral response in Mo₂N enables enhanced photogenerated charge collection. Driven by an internal electric field (IEF), recombination with g-C₃N₄ can form Schottky junctions, promote directional transfer of electrons, and substantially inhibit electron-hole pair recombination. Thus, g-C₃N₄ exhibited significantly boosted photocurrent under visible light. Through π-π conjugation effect, an aptamer specifically recognizing DIA was introduced at the electrode interface, establishing the PEC sensing interface. The PEC aptasensor constructed based on this achieves highly sensitive and specific detection of DIA. The sensor showed a broad linear range (5 ×10^-3-1 ×10³ pM) and an ultra-low detection limit (1.67 ×10^-3 pM) for DIA. Moreover, it exhibited remarkable accuracy, selectivity, and applicability when applied to real water samples. This work extends the application of Schottky junctions to the sensitive detection of pesticide residues and achieves effective amplification of sensing signals, providing profound insights for constructing excellent PEC aptasensors.