Fabrication and photoelectrochemical characterization of CdS particles in nanospaces of expandable mica

Photoelectrochemical properties are investigated for CdS nanoparticles formed in a solution as well as in the nanospaces of expandable mica (EM). The smallest sized CdS particles (≈3 nm in diameter) were obtained in the nanospaces of Cd2+ exchanged EM (1.2 μm in crystal size) by reacting with H2S in the absence of interlayer water. The existence of interlayer water was found to influence the size of CdS particles remarkably. Smaller EM crystals limited the particle growth of CdS along the sheets. Photocurrent was measured for the CdS-EM suspensions/methylviologen system and the CdS-EM film electrode. The variation of the steady state photocurrent value (iss) with pH, showed that iss increased with the decrease of CdS particle size, while the intersection point (termed as pH0) showed a negative shift with the decrease of CdS particle size. The action spectrum of the CdS-EM film electrode was in good agreement with their absorption spectra of the suspension.