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.