Direct Redox Sensing of Caffeine Utilizing Zinc-Doped Tin Oxide Nanoparticles as an Electrocatalyst.

Objective: In addition to its positive benefits, caffeine also has harmful consequences. Therefore, it is essential to ascertain its content in various substances. Impact Statement: The present study emphasizes a novel way of quantification of caffeine in real as well as laboratory samples based on a nanomaterial-assisted electrochemical technique. Introduction: Electrochemical sensing is a prominent analytical technique because of its efficiency, speed, and simple preparation and observations. Due to its low chemical potential, SnO₂ (tin oxide) demonstrates rapid redox reactions when used as an electrode. The presence of shielded 4f levels contributes to its distinctive optical, catalytic, and electrochemical capabilities. Methods: An efficient coprecipitation approach, which is simple and rapid and operates at low temperatures, is utilized to produce zinc-doped tin oxide nanoparticles (Zn-SnO₂ nanoparticles). Zinc doping is used to modify the optoelectronic characteristics of tin oxide nanoparticles, rendering them very efficient as electrochemical sensors. Results: The crystal structure of samples was analyzed using x-ray diffraction, electronic transitions were calculated using ultraviolet-visible spectroscopy, and surface morphology was analyzed using field emission scanning electron microscopy. The x-ray diffraction investigation revealed that the produced Zn-doped SnO₂ nanoparticles exhibit tetragonal phases, and the average size of their crystallites reduces upon doping Zn with SnO₂. The bandgap energy calculated using the Tauc plot was found to be 3.77 eV. Conclusion: The fabricated caffeine sensor exhibits a sensitivity of 0.605 μA μM ^-1 cm^-2, and its limit of detection was found to be 3 μM.