SnO2 Nanofibers Decorated with Au Nanoparticles for Ru(bpy)32+ Sensitized Photoelectrochemical Determination of NO2- in Urine

Abstract A three-dimensional (3D) network nanocomposite is constructed by electrospinning tin dioxide nanofibers (SnO2 NFs) on the surface of indium tin oxide (ITO) and then in-situ electrodepositing gold nanoparticles (AuNPs). With the aid of large surface area of SnO2 NFs and the surface plasmon resonance (SPR) effect of AuNPs, the novel 3D architecture is beneficial to the mass transfer and the separation efficiency of photogenerated electrons and holes. In the presence of photosensitizer of Ru(bpy)32+ (tris (2,2'-bipyridyl) dichlororuthenium (II) hexahydrate (Ru(bpy)3(PF6)2), the ITO/SnO2-AuNPs electrode shows good photoelectrochemical (PEC) response to nitrite (NO2-) under visible light irradiation. The linear range for NO2- determination is from 10-9 to 10-5 M with a low detection limit of 4.8 × 10-10 M. The ITO/SnO2-AuNPs photoanode based PEC sensor is also successfully applied to analyze trace NO2- in human urine, showing excellent anti-interference and stability. This work may pave the way for designing noble metal-semiconductor heterogeneous materials with tailored properties for the field of biosensor design.