Surface plasmonic hot hole driven Ag2S/Au/Al2O3 photocathode for enhanced photoelectrochemical water splitting performance

Herein, Ag2S/Au/Al2O3 photoelectrode was fabricated for superior photoelectrochemical (PEC) water splitting response. The working electrodes were deposited using the glancing angle deposition (GLAD) method followed by RF sputtering and atomic layer deposition (ALD). The as-prepared Ag2S/Au/Al2O3 samples revealed a higher photocurrent density of 2.50 mA/cm2 (at 0.95 V Ag/AgCl) as compared to bare Ag2S (1.70 mA/cm2) with a corresponding less charge transfer resistance at the semiconducting interface. The superior PEC response may be ascribed to the synergic effect of plasmonic Au nanoparticles and the tilted Ag2S nanorods. The plasmonic effect of Au nanoparticles increases the visible-light response of Ag2S as well as provides the hot holes to enhance the photocurrent density. In addition, the increased trapping of light due to the tilted architecture of Ag2S nanorods resulted in an effective absorption of light. The theoretical simulations based on finite difference time domain (FDTD) were also performed to explore the distribution of the electric-field intensity and optical trapping of light between the nanorods of Ag2S and Ag2S/Au. The experimental and theoretical results show a deeper insight into the role of plasmonic nanostructures decorated Ag2S nanorods and shed light on designing hybrid hot hole harvesting semiconductor nanostructures for the next generation photoelectrodes.