Precursor Effects of Citric Acid and Citrates on ZnO Crystal Formation

Abstract

We have studied the precursor effects of citric acid and various citrates-including triethyl citrate, tripotassium citrate, trisodium citrate and triammonium citrate-on the formation of ZnO crystals in alkaline solution. These citrate-related chemicals could be divided into three groups (group A, triethyl citrate; group B, tripotassium citrate and trisodium citrate; and group C, citric acid and triammonium citrate) based on their activity for modifying the ZnO growth direction and solution pH dependency on their concentration. We could obtain ZnO structures with various distinct morphologies by simply changing the concentration of citric acid or citrate additive dissolved in the alkaline reaction solution. On the basis of the results, we propose the growth mechanisms underlying the formation of the various ZnO structures in the absence and presence of citric acid or citrate additives.

Preparation of Flower-like ZnO Nanoparticles in a Cellulose Hydrogel Microreactor

“…The II-VI compound semiconductor has outstanding electrical and optical properties (Cho et al 2009) as well as excellent chemical and thermal stabilities. Zinc oxide has a wide direct band gap at 3.37 eV and an exciton binding energy of 60 meV (Su et al 2010).…”

Contribution of TEMPO-Oxidized Cellulose Gel in the Formation of Flower-Like Zinc Oxide Superstructures: Characterization of the TOCgel/ZnO Composite Films

“…Moreover, different soft templates/capping agents such as water-soluble polymers [24][25][26], citrate salts [27,28], surfactants [29][30][31], a mixture of sodium citrate and alkylamine [23], citric acid [25], ethylene diamine [32], and amino acids [33] have been successfully used in wet-chemical methods. In this context, Sun et al have developed a method to fabricate novel flower-like 3D ZnO superstructures in aqueous solution and using trisodium citrate dihydrate as a surfactant to enhance the nucleation-growth process implied in the formation of such hierarchical superstructures [34].…”

UV-protection of wood surfaces by controlled morphology fine-tuning of ZnO nanostructures

“…The morphology of ZnO nanostructures can be adjusted during the growth process in presence of ammonium citrate forming a continuous film of ZnO platelets as depicted in Figure 1c. Here, the c-axis oriented growth is suppressed because citrate preferentially binds to the polar {002} faces of hexagonal ZnO (Cho et al 2009). …”

“…The selective area electronic diffraction pattern (SAED) confirms that the dense ZnO film grows along the [001] direction (Figure 4b). Because in the presence of ammonium citrate the growth of ZnO along the [001] direction is suppressed (Tian et al 2003;Cho et al 2009), the ZnO crystals on wood surface have the tendency to grow along the [100] direction, i.e. parallel to wood surface.…”