Anodic aqueous electrophoretic deposition of titanium dioxide using carboxylic acids as dispersing agents

Abstract

The dispersion of anatase phase TiO 2 powder in aqueous suspensions was investigated by zetapotential and agglomerate size analysis. The iso-electric point (IEP) of anatase was determined to be at pH 2.8 using monoprotic acids for pH adjustment. In comparison, it was found that the use of carboxylic acids, citric and oxalic, caused a decrease in zeta-potential through the adsorption of negatively charged groups to the particle surfaces. The use of these reagents was shown to enable effective anodic electrophoretic deposition (EPD) of TiO 2 onto graphite substrates at low pH levels with a decreased level of bubble damage in comparison with anodic EPD from basic suspensions. The results obtained demonstrate that the IEP of TiO 2 varies with the type of reagent used for pH adjustment. The low pH level of the IEP and the ability to decrease the zeta-potential through the use of carboxylic acids suggest that the anodic EPD of anatase is more readily facilitated than cathodic EPD.

Inkjet Printing of Titanium Dioxide Photoanodes for Dye Sensitized Solar Cells

“…The exact method for stabilizing the dispersion of the particles is determined by the requirements of the specific application. In electrophoretic deposition, for example, dispersing agents that bind directly to the nanoparticles are to be avoided as they interfere with attractive forces between surface charges and the opposite charges placed on a target surface [26].…”

“…The concerns stem primarily from negative reactions to TiO 2 nanoparticles observed under laboratory conditions with exposed rats [26]. There is associated with these observations the belief that nanoparticles are able to penetrate living cells with ease and once inside, can proceed to disrupt cellular function, especially as individual particles aggregate into larger masses.…”

“…Taken together, the Stern and secondary ion layers are referred to as the Interfacial double layer or Electronic double layer (EDL). The interface between the double layer and the surrounding medium is called the Slipping plane [26]. The Slipping plane is the spatial limit of the nanoparticle to maintain a hold on ionic charges; inside the EDL the counter-ions are held with enough electrostatic force to ensure that they move in consert with the nanoparticle.…”

“…The size and morphology of the nanoparticles will also influence the stability. Guiot and Spalla [26], based on a study of four different TiO 2 nanoparticles, identified a general range of dispersion instability for pH values between 5 and 9. Each of the TiO 2 particles studied by Guiot and Spalla were believed to have been coated with various substances to promote dispersion stability.…”

Electrophoretic deposition of nc-TiO2/chitosan composite coatings on X2CrNiMo17-12-2 stainless steel

“…Chitosan is a polysaccharide, produced by deacetylation of chitin, which has a proven biocompatibility and antibacterial properties [11]. TiO 2 deposition on metal surface can be executed by use of many techniques, such as plasma spray technique [12,13], sol -gel [14,15], micro arc oxidation [16,17] and electrophoretic deposition (EPD) [18][19][20][21]. Chitosan, as biopolymer, is destroyed by high temperature.…”