Effect of functional groups on the crystallization of ferric oxides/oxyhydroxides in suspension environment

Abstract

This paper investigated the effects of five kinds of Au surfaces terminated with and without functional groups on the crystallization of ferric oxides/oxyhydroxides in the suspension condition. Self-assembled monolayers (SAMs) were used to create hydroxyl (--OH), carboxyl (--COOH), amine (--NH₂) and methyl (--CH₃) functionalized surfaces, which proved to be of the same surface density. The immersion time of substrates in the Fe(OH)₃ suspension was divided into two time portions. During the first period of 2 h, few ferric oxide/oxyhydroxide was deposited except that ?-Fe₂O₃ was detected on--NH₂ surface. Crystallization for 10 h evidenced more kinds of iron compounds on the functional surfaces. Goethite and maghemite were noticed on four functional surfaces, and maghemite also grew on Au surface. Deposition of ?-Fe₂O₃ was found on--OH surface, while the growth of orthorhombic and hexagon FeOOH were indicated on--NH₂ surface. Considering the wide existence of iron compounds in nature, our investigation is a precedent work to the study of iron biomineralization in the suspension area.

Keywords

biocrystallization / suspension / ferric oxide/oxyhydroxide / functional group