Photoresponsive surfaces nanoparticles

In order to improve the sensitivity of the photodetectors, the metal nanoparticles (Ag, Au, etc.) were loaded onto the ZnO nanofibers to enhance the photoresponse. The origin for the enhancement is related to the enhanced separation of photogenerated electron-hole pairs and the resulted efficient discharge of surface states. For example, the photoresponsive properties of Au/ZnO nanofibers were dramatically enhanced compared with ZnO nanofiber by regulating the concentration of the nanoparticle content ones (Fig. 11.7d). Furthermore, ZnO nanofibers could also be used to detect organic gases under UV illumination, such as ethanol, acetone, toluene, and benzene the Au nanoparticle decoration would also remarkably enhance the sensitivity of the sensors as expected [135]. 

A third alternative to introduce visible light photoresponse that was commented above is deposition of metal nanoparticles exhibiting surface plasmon band [40]. Due to the chemical stability and inertness against oxidation, Au nanoparticles are the most adequate metal for the purpose of introducing visible light photoresponse. We have already commented the case of Au-Cu/P25 as a photocatalyst for CO2 reduction reaching high CO2 conversion rates. 

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