Facile synthesis of Au-SnO₂ hybrid nanospheres with enhanced photoelectrochemical biosensing performance

Au-SnO₂ hybrid nanospheres (HNSs) were synthesized by a facile, one-step method, which was achieved via a redox reaction between the reductive stannous (ii) ions and oxidative auric (iii) ions and dissolved O₂, and then in situ formation of Au nanoparticles (NPs) and SnO₂ NPs. The results indicated that the Au NPs are able to trap electrons, improve the electron-hole pairs' life, and enhance the visible light absorption intensity that are all beneficial for enhancement of the visible light photoelectrochemical performance. Cysteine was chosen as a model molecule in photoelectrochemical biosensing experiments. The biosensor displayed excellent analytical performance for detection of cysteine with an extremely broad linear range (from 0.4 μM to 12 mM), and a low detection limit (0.1 μM). Therefore, the Au-SnO₂ HNSs will be promising candidates for photocatalysts, photoelectrochemical biosensors, and other photoelectric devices.