Electrochemical sensing of hydrogen peroxide using SnO₂-SA nanoparticles with enhanced catalytic activity

Accurate quantification of hydrogen peroxide (H₂O₂) is essential for biomedical analysis and process monitoring, yet metal-oxide sensors often suffer from limited active-site exposure and sluggish charge transport. Here we report a sodium-alginate (SA)-templated route to porous SnO₂ nanoparticles (SnO₂-SA) that integrates high crystallinity with abundant surface oxygen vacancies and a permeable mesoporous network. When drop-cast on a glassy carbon electrode (GCE), the SnO₂-SA enables non-enzymatic H₂O₂ detection with a wide linear range of 0.02-2.8 mM, high sensitivity of 381.12 μA mM^-1 cm^-2, and a low detection limit of 0.61 μM at -0.4 V. The sensor exhibits strong anti-interference behavior, excellent reproducibility and repeatability, and retains 97.8% of its initial response after 15 days. Beyond sensing, SnO₂-SA shows antibacterial activity against E. coli and S. aureus and measurable DPPH-radical scavenging, suggesting utility in mitigating biofouling and stabilizing local redox environments during long-term measurements. This green, scalable SA-templating strategy affords multifunctional SnO₂ nanomaterials with promising prospects in electrochemical sensing, antimicrobial protection, and broader biomedical analysis.