Semiconductor Particles and Particulate Films in Membrane-Mimetic Compartments

4 Semiconductor Particles and Particulate Films in Membrane-Mimetic Compartments 

Membrane-mimetic compartments are being increasingly utilized as hosts for semiconductor particles and particulate films. Available information is summarized in Table 7 [611-709]. 

Aqueous pools of reversed micelles have been fruitfully employed for the in situ generation of semiconductor particles. The first publication in this area described the formation of CdS in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) aggregates in isooctane [611]. The preparation involved the addition of aqueous CdCl or Cd(N03)2 to isooctane solutions of AOT. Exposure to controlled ammeters of the CdS particles formed. Irradiation of degassed, AOT-reversed-micelle-entrapped, platinized CdS by visible light (450-W Xenon lamp X 350 nm) in the presence of thiophenol (PhSH) resulted in sustained hydrogen formation. Sacrificial electron transfer occurred from thiophenol to positive holes in the colloidal CdS and, consequently, diminished undesirable electron-hole recombinations (Fig. 101) [611]. 

A higher level of size and morphology control in the incipient semiconductors has been accomplished in reversed micelles prepared from cadmium AOT [614] and from mixtures of cadmium AOT and sodium AOT [615] or, alternatively, by arresting particle growth by surface derivatization [592, 621, 622]. Indeed, surface derivatization of semiconductor clusters was first reported for particles in reversed micelles [621] the reversed micelles act to confine precursor ions and to control the growth of the semiconductor particles. Conditions are typically arranged so that, initially, there is no more than one metal ion (say Cd2+) per water pool. Addition of a heptane solution of bis(trimethylsilyl) selenium resulted in the formation of size-quantized metal selenide particles (say CdSe) in the reversed micelles. This solution could be evaporated to dryness and the resultant particles could be reconstituted in a hydrocarbon solvent Alternatively, addition of metal (say Cd2+) ions to the reversed-micelle-entrapped metal selenide particles, followed by the addition of alkyl(trimethylsilyl)selenium, RMSiMe3, led to the formation of alkyl-capped 

Membrane-mimetic compartment Incorporated semiconductors) Comments 

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Table 7. Semiconductor particles and particulate films in membrane-mimetic compartments...

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