Figure 1.

Schematic illustration of the synthesis of Pt/Si/Ag nanowire heterostructures. (a) Schematic illustration of a metal-semiconductor-metal photoelectric nanodevice as a highly efficient photocatalyst. A Pt/n-Si/Ag heterostructure is created in a single nanowire to integrate a nanoscale metal-semiconductor Schottky photodiode (Pt-Si) encased in a protective insulating shell with two exposed metal catalysts (Pt, Ag). (b) The starting lightly doped silicon wafer. (c) Formation of silicon nanowire arrays by silver-assisted electroless wet chemical etching. (d) Formation of silicon oxide shell on Si nanowires by baking the sample under ambient conditions at 900 °C for 60 min. (e) Spin coating of photoresist AZ 5214 as a protecting layer for the substrate. (f) Exposure of the tips of the silicon nanowires through O₂ plasma etching. (g) Exposure of the Si core of the silicon oxide-encased Si nanowires by oxide dry etching. (h) Drilling of the nanoholes in the Si nanowires by XeF₂ dry etching. (i) Pt electrodeposition. (j) Removal of photoresist AZ 5214. (k) Release of Pt/Si nanowires into solvent through sonication. (l) Self-catalyzed photoreduction of silver by irradiation on freshly released Pt/Si nanowires in AgNO₃ aqueous solution.