Novel Synthesis of LaFeO 3 Nanostructure Dendrites: A Systematic Investigation of Growth Mechanism, Properties, and Biosensing for Highly Selective Determination of Neurotransmitter Compounds S. Thirumalairajan, † K. Girija, † V. Ganesh, ‡ D. Mangalaraj, † C. Viswanathan, † and N. Ponpandian* ,† † Department of Nanoscience and Technology, Bharathiar University, Coimbatore - 641 046, India ‡ Electrodics and Electro Catalysis Division, Central Electrochemical Research Institute (CSIR-CECRI), Karaikudi - 630 006, India ABSTRACT: Single-crystalline novel LaFeO 3 dendritic nano- structures are synthesized by a well-controlled, surfactant- assisted facile hydrothermal process. The morphology of the material is investigated by high-resolution transmission and scanning electron microscopy. The crystal nature and chemical composition of LaFeO 3 dendritic nanostructures are revealed from the X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Structural characterizations imply the preferential growth along the [121] direction by oriented attachment of LaFeO 3 nanoparticles in the diffusion limit, leading to the formation of LaFeO 3 dendrites. The microscopic studies confirm the formation of dendrites with a length of 3-4 μm, a branch diameter of 80 nm, and a length of 1-1.5 μm. The possible growth mechanism of the dendritic morphology is discussed from the aspect of diffusion and oriented attachment based on experimental results. Further, the electrochemical measurements performed on LaFeO 3 dendritic nanostructures deposited on the surface of a glassy carbon electrode exhibit a strong promoting effect. The oxidation current is proportional to concentration in the linear range of 8.2 × 10 -8 to 1.6 × 10 -7 M with a detection limit of 62 nM at S/N = 3. Meanwhile, the sensor effectively avoids the interference of ascorbic acid and uric acid, and it is successfully applied to determine the dopamine formulations with high selectivity and sensitivity. 1. INTRODUCTION Shape- and size-controlled synthesis of functional nanostruc- tures, such as nanoparticles, nanocubes, nanospheres, nano- wires, and nanorods, has gained importance as they exhibit unique electronic, optic, magnetic, and catalytic properties. 1-4 Especially, substantial attention has been focused on dendritic structures that can be applied in scientific and technological applications due to their large surface area and continuous networks. 5,6 In addition, the dendritic structures provide fundamental scientific opportunities for investigating the influence of size and dimensionality with respect to their collective novel properties and applications resulting from the spatial orientation and arrangement of nanoparticles. Generally, dendrite structures of metal oxide exhibit nonequilibrium growth processes that provide a natural framework for the study of disordered systems. Numerous theoretical and experimental results were reported, which contain information about the structure and growth mechanism of dendrites possessing promising complex functions, and their properties are highly dependent on the morphology. 7,8 The perovskite oxide with dendrite nanostructures also have many special characteristics, such as a large surface area composed of major trunks and branches. The preparation of dendritic structures with well-defined shapes may open new opportunities for wide applications in nanodevices. 9 Recently, a variety of dendrite crystals of metals, 10-12 metal oxides, 13 and chalcogenides 14 have been extensively studied theoretically and experimentally. Despite intensive experimental efforts, the dendritic structures of perovskite oxides have not been successfully obtained until now, which has hindered detailed experimental investigation of the morphology-dependent properties of these oxides. It is well-known that the properties of nanoparticles are dependent not only on their chemical composition but also on their structure, shape, and size. Therefore, the ability to tune the size and shape of LaFeO 3 nanostructures with tailored properties is significant for various investigations. Over the past decade, many chemical methods, such as sol- gel, coprecipitation, combined polymerization, pyrolysis of metallo-organic precursors, and hydrothermal routes, 15-19 have been developed to prepare LaFeO 3 nanostructures with controlled physical and chemical characteristics. Among the various conventional techniques, the hydrothermal technique is an aqueous-based precipitation route allowing control over the nucleation, growth, and aging process. Surfactants as soft templates are involved in the formation of di fferent morphologies by the self-assembly process. The combination of surfactant-assisted self-assembly under hydrothermal con- ditions has been used by many researchers to synthesize different morphologies. 20 The hexadecyltrimethyl ammonium bromide (CTAB) is used as a surfactant in the synthesis of Received: September 28, 2012 Revised: November 15, 2012 Published: November 21, 2012 Article pubs.acs.org/crystal © 2012 American Chemical Society 291 dx.doi.org/10.1021/cg3014305 | Cryst. Growth Des. 2013, 13, 291-302