Mechanistic insights of the oxidation of bisphenol A at ultrasonication assisted polyaniline-Au nanoparticles composite for highly sensitive electrochemical sensor

In this work, a conducting polymer and nanometal composite electrocatalyst was prepared for the sensitive detection of bisphenol A (BPA) over a wide concentration window. Polyaniline (PANI) was first prepared from aniline through a chemical method, and gold nanoparticles (AuNPs) were embedded with the prepared PANI via ultrasonication to obtain the PANI_AuNPs electrocatalyst. The morphological, chemical, and electrochemical properties of the electrocatalyst were then determined, and BPA oxidation was investigated with the help of electroanalytical techniques to understand the electron-transfer process occurring at the PANI_AuNPs interface. The results showed that BPA was oxidized through a multistep electron-transfer process without any intermediate chemical step, and the rate-determining step was the second electron-transfer step. The oxidation proceeded as a 2e^–/2H⁺ process with an electron-transfer coefficient of ≈0.69. These results indicate that the PANI and AuNPs work synergistically to promote the electron transfer from BPA. The quantitative analysis gave a broad linear range and a low limit of detection of 0.4 nM. The sensor was also tested for the detection of BPA in tap water, bottled water, and a canned beverage for real sample analysis.