Interfacial chemical bonding enhanced SnO₂ NPs@AC composite for highly sensitive electrochemical detection of dopamine

One-step co-hydrothermal synthesis of SnO₂ NPs@AC composite without tedious template procedures. • In-situ formed Sn O C interfacial bonds confirmed by XPS and Raman, enhancing charge transfer. • Uniform dispersion of SnO₂ nanoparticles (∼12 nm) on porous AC matrix, maximizing electroactive surface area. • Excellent dopamine sensing: LOD 21.6 nM, high sensitivity, good reproducibility, and recovery in serum. In this study, a SnO₂ nanoparticles@amorphous carbon (SnO₂ NPs@AC) composite was successfully synthesized via a facile co-hydrothermal method followed by high-temperature calcination, using glucose as the carbon precursor and SnCl₄ as the tin source. The structural and morphological properties of the as-prepared composites were systematically characterized. The results confirmed that the ultrafine SnO₂ NPs were uniformly dispersed and firmly anchored on the AC surface through in situ formed Sn O C chemical bonds, creating an intimately coupled heterointerface. Owing to this unique architecture, the SnO₂ NPs@AC-modified electrode exhibited excellent electrochemical sensing performance for dopamine (DA). Under optimized conditions, the sensor delivered a wide linear response in the range of 0.2–20 μM, a low detection limit of 2.16 × 10 −2  μM, and a high sensitivity of 1.33 μA·μM −1 . Moreover, the sensor demonstrated excellent selectivity against common interferents. When applied to real biological samples (fetal bovine serum), satisfactory recovery rates ranging from 97.7 to 100.9% were achieved. However, its long-term stability (∼60% retention after 10 days) remains a limitation that requires further improvement for practical applications. This study provides a simple and scalable strategy for constructing high-performance hybrid electrode materials through interfacial chemical bond engineering, with promising potential for biomedical sensing applications. Download: Download high-res image (90KB) Download: Download full-size image