Hot-Electron Injection and Charge Carrier Lifetime Prolongation Enhance the Photoelectrochemical Performance of a Plasmonic CdS/Au Photoanode

The utilization of the surface plasmon resonance effect of plasmonic noble metal Au or Ag nanostructures is an effective paradigm for increasing the photoelectrochemical performance of photoelectrodes. Here, a plasmonic heterojunction photoanode was fabricated by employing a facile solution reduction method to grow Au nanoparticles onto hydrothermally prepared CdS nanorod arrays (NRAs). The maximum photocurrent density of the constructed CdS/Au NRAs with optimized Au nanoparticle loading reaches up to 1.81 mA cm–2, 3.5-fold that of pure CdS NRAs. The highest solar-to-hydrogen conversion efficiency of CdS/Au NRAs is 1.25% at 0.3 V versus the reversible hydrogen electrode, 5-fold that of bare CdS NRAs. The measurements demonstrate that the improved photoelectrochemical activity of CdS/Au heterojunction NRAs is attributed to the hot-electron injection of Au nanoparticles and the prolonged charge carrier lifetime. This work demonstrates a promising approach for using the surface plasmon resonance effect of Au nanostructures to improve the solar energy conversion efficiency of photoanodes.