Silicon Nanowires/Reduced Graphene Oxide Composites for Enhanced Photoelectrochemical Properties

The top of silicon nanowires (SiNWs) arrays was coated with reduced graphene oxide (rGO) by the facile spin-coating method. The resulting SiNWs/rGO composite exhibits enhanced photoelectrochemical properties, with short-circuit photocurrent density more than 4 times higher than that of the pristine SiNWs and more than 600 times higher than that of planar Si/rGO composite. The trapping and recombination of photogenerated carriers at the surface state of SiNWs were reduced after the application of rGO. The results of electrochemical impedance spectroscopy measurements suggest that the reduction of trapping and recombination of photogenerated carriers as well as remarkably enhancement of photoelectrochemical properties can be attributed to the low charge transfer resistance at the SiNWs–rGO interface and rGO–electrolyte interface. The method and results shown here indicate a convenient and applicable approach to further exploitation of high activity materials for photoelectrochemical applications

Tungsten Sulfide Enhancing Solar-Driven Hydrogen Production from Silicon Nanowires

Tungsten sulfides, including WS₂ (crystalline) and WS₃ (amorphous), were introduced to silicon nanowires, and both can promote the photoelectrochemical hydrogen production of silicon nanowires. In addition, more enhancement of energy conversion efficiency can be achieved by the loading of WS₃, in comparison with loading of WS₂. Polarization curves of WS₃ and WS₂ suggest that WS₃ has higher catalytic activity in the hydrogen evolution reaction than WS₂, affording higher energy conversion efficiency in silicon nanowires decorated with WS₃. The higher electrocatalytic activity of WS₃ correlates with the amorphous structure of WS₃ and larger surface area of WS₃, which result in more active sites in comparison with crystalline WS₂