Effects of surface charges and surface states of chemically modified cadmium sulfide nanoparticles immobilized to gold electrode substrate on photoinduced charge transfers

Masahide Miyake, Tsukasa Torimoto, Matsuhiko Nishizawa, Takao Sakata, Hirotaro Mori, Hiroshi Yoneyama

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

Cadmium sulfide nanoparticles (Q-CdS) modified with 2-mercaptoethanesulfonate and 2-aminoethanethiol in a molar ratio of 2:1 were covalently immobilized onto an Au surface covered with a self-assembled monolayer of 3,3′-dithiobis(succinimidylpropionate), and the resulting electrodes were further immobilized with Q-CdS using glutaraldehyde as a binding agent. The degree of anodic photocurrents was greatly influenced by charged conditions of hole scavengers used because of the presence of sulfonate groups on the Q-CdS surfaces; triethylamine having positive charges gave large photocurrents, triethanolamine medium photocurrents, and formate small photocurrents. If Q-CdS having a large emission from their surface trap states was used, anodic photocurrents were depressed with increasing anodic polarization from the onset potentials which were ca. -1.1 V vs SCE for the use of any kinds of hole scavengers, and the greatest depression appeared at -0.25 V, beyond which a steep increase in anodic photocurrents was seen. In contrast, no significant depression in photocurrents was observed and anodic photocurrents were monotonically increased, in the case of using Q-CdS having an intense band-gap emission. When the energetic position at the emission maximum is correlated to the potential at which the greatest photocurrent depression appeared, photocurrent-potential characteristics are discussed in terms of involvements of surface states in the photoelectrode reactions.

Original languageEnglish
Pages (from-to)2714-2718
Number of pages5
JournalLangmuir
Volume15
Issue number8
DOIs
Publication statusPublished - 1999 Apr 13
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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