In situ grown AuNPs on MXene/rice husk biochar nanocomposites for high-performance electrochemical sensing of acetaminophen

Acetaminophen (APAP), a widely used analgesic and antipyretic, poses significant health risks upon prolonged or excessive exposure, necessitating sensitive and reliable detection methods. Herein, we fabricated an electrochemical sensing platform for APAP detection based on a novel rice husk biochar (RHB)/MXene–AuNPs composite. The composite synergistically integrates RHB's (derived from agricultural waste) sustainable porous architecture, MXene's excellent conductivity and AuNPs’ abundant catalytic sites, enabling efficient APAP oxidation. The sensing platform achieves a linear quantification range of 0.03–8.88 µM with an ultrasensitive detection limit of 21.4 nM (S/N = 3). It also exhibits robust stability (RSD < 1% after 110 cycles), high reproducibility (2.32% RSD across electrodes), and excellent selectivity against 50-fold excess interferents. Validation using commercial 999 Cold and Flu Granules yields recoveries of 96.2–101.7%, confirming its accuracy. This work pioneers a sustainable sensing strategy by transforming rice husk waste into a high-value electrode material, offering a robust, precise, and eco-friendly approach for APAP quantification in pharmaceutical and clinical applications.