Electrodeposition of Fluorescent Si Nanomaterial from Acidic Sodium Silicate Solutions
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A8.10.1
ELECTRODEPOSITION OF FLUORESCENT SI NANOMATERIAL FROM ACIDIC SODIUM SILICATE SOLUTIONS LAILA H. ABUHASSAN, Department of Physics, University of Jordan, Amman, Jordan MUNIR H. NAYFEH b) * Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801 * Research Division, NanoSi Technologies, Inc., EnterprizeWorks, Champaign, IL 61820
ABSTRACT We developed a procedure for the electrodeposition of fluorescent silicon nanomaterial from silicates on conducting substrates. The electrodeposion solution used is a solution of sodium metasilicon salts (Na2SiO3) in HF/H2O2. When a positively biased platinum substrate is immersed in the bath, a current is drawn and a thin fluorescent coating is formed on the substrate. We discuss the results in terms of current-induced nucleation of silicon nanostructures. INTRODUCION A variety of techniques and materials have been used to synthesize Si nanostructures. The most popular of the procedures is the use of elemental Si. Electrochemical etching of Si wafers is used to produce porous Si [1] or dispersions of Si nanoparticles [2]. Wafers were also ablated into Si particles by laser irradiation [3]. Embedded Si nanoclusters were formed by implanting Si ions into quartz, followed by annealing at elevated temperatures [4]. A variety of compounds were also used. Silane gas subjected to slow combustion [5], thermal decomposition [6], microwave plasma excitation [7], gas-evaporation [8], or chemical vapor deposition (CVD) [9] each yields Si nanoclusters. Nanoclusters were also synthesized via a reduction of anhydrous Si halogen ionic salts SiX4 (X = Cl, Br) with LiAlH4 [10], RSiCl3 (R = H, C8H17) [11], or alkali Si salts ASi (A = Na, K) [12]. Diphenyl silane (SiH2Ph2) in the presence of octanol was also used [13]. In this paper, we present a procedure for deposition of fluorescent Si nanomaterial from silicate solutions on conducting surfaces. The electrodeposion solution used is a solution of sodium metasilicon salts (Na2SiO3) in HF/H2O2. When a positively biased platinum substrate is immersed in the solution a thin coating forms on the substrate. We discuss the results in terms of current-induced nucleation of Si nanostructures. EXPERIMENTAL DETAILS We start with a commercial metasilicate water solution (Na2SiO3.5H2O2) of 1mg/liter. It is mixed in a premixed HF:H2O2 solution. The metasilicate solution includes 0.02 percent of pentachlorophenol (C6Cl5OH) as a preservative. The substrate is a platinum foil. The foil is immersed in the solution vertically, and a counter electrode made of a platinum wire is also immersed vertically. We bias the substrate positively and the counter wire negatively and set a current of 10 mA. The substrate is removed after a certain period of time and rinsed with deionized water. The fluorescence activity is examined using a fluorescence microscope.
A8.10.2
RESULTS AND DISCUSSION Figure 1 shows an image taken under UV irradiation from a mercury lamp at 365 nm. We believe that the process involves deposition of Si atoms from silic
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