Palladium nanoparticles anchored MoS₂-MXene composite modified electrode for rapid sensing of toxic bisphenol A in aqueous media

Bisphenol A (BPA) is a commonly used, highly toxic organic phenolic that can damage the human nervous, reproductive, and immune systems, and thus, a rapid onsite test method is required to detect BPA in environmental samples. In this research, we coated screen-printed carbon electrodes (SPCEs) with Pd nanoparticles (NPs) anchored on a MoS_2-modified MXene nanoarchitecture for the accurate onsite sensing of BPA contamination in aquatic environmental samples. Pd-MoS₂-MXene-SPCEs were prepared using a one-step hydrothermal technique followed by chemical reduction. The optimized SPCE had a low R_ct of 63 Ω and excellent electrocatalytic efficiency for BPA oxidation and a remarkably high current density at the lowest anodic potential (0.57 V vs. Ag/AgCl) in 0.05 M phosphate buffer (pH 7). The charge-transfer rate (k_s) and the saturation absorption capacity (or surface-excess) (Γ) of the Pd-MoS₂-MXene-SPCEs were 3.14 s⁻¹ and 5.62 × 10^-9 mol cm⁻², respectively. Under optimal conditions, square wave voltammetry responses to BPA concentration were linear in the range 5 to 175 nM, and exhibited high sensitivity (16.205 μA nM⁻¹ cm⁻²) and a detection limit of 0.12 nM (3.3 σ/s). The optimized SPCE exhibited high reproducibility, reusability, and repeatability with a relative standard deviation (RSD) of < 5.0% and excellent stability and retained 89.2% of its initial sensitivity after 30 days of storage for the onsite sensing of BPA. The prepared sensor showed excellent selectivity for the quantification of BPA even in the presence of electrochemically active interfering compounds such as drugs, pollutants, biological substances, and some common cations/anions. Real-time quantitative analysis of BPA in milk and river and lake water samples was performed, and acceptable recoveries were obtained (from 89.1 to 107.8%) with an RSD of 2.2–3.8%, demonstrating an accuracy similar to that of HPLC.