Twinned Zn₂TiO₄ Spinel Nanowires Using ZnO Nanowires as a Template

Abstract

One-dimensional (1D) semiconductor metal oxide nanostructures, such as nanowires, nanobelts, and nanotubes, have attracted considerable attention due to their prominent electrical, optical, and chemical properties and potential applications in nanoscale electronic and optoelectronic devices. [1][2][3][4][5] However, the properties and applications of those nanomaterials are limited by their simple binary systems.[6] Therefore, synthesis of complex functional nanomaterials with controlled size and morphology, such as core/shell quantum dots, [7] nanowires and nanobelts, [8][9][10][11] heterostructures, [6,12] superlattices, [13] and nanotubes, [14][15][16] are highly desirable. Furthermore, 1Dternary nanocomposites, such as Zn 2 SnO 4 , [8][9][10]17] Zn 2 TiO 4 , [18] ZnGa 2 O 4 , [11,16] MgAl 2 O 4 , [14] CoFe 2 O 4 , [19] exhibit specific functions that are unattainable by common binary composites. Conventional synthesis methods of those ternary composites usually involve high-energy ball milling of two binary solid oxides [18] or a high-temperature solid reaction, [20,21] which are not suitable for 1D nanostructure growth. Only recently, syntheses of single-crystal ternary oxide nanowires and nanotubes have been achieved by using Ga 2 O 3 , MgO, or ZnO nanowires as template. [11,14,15] For face-centered cubic (fcc) nanostructures, twinning is probably the most common structural defect, especially in metal and metal alloy nanoparticles, [22,23] where two subcrystallites share a facet to form a mirror image of each other. Twinning is occasionally observed in binary systems, such as cubic ZnS and InP nanowires, [24,25] both of which have a preferential <111> growth direction. However, reports on the synthesis of twinned structures of fcc ternary nanowires are rare; [10] that is, the formation of twinned nanowires has yet to be revealed.Zinc titanate (Zn 2 TiO 4 ) is an inverse spinel, which has been used as a catalyst and pigment in industry. It is one of the leading regenerable catalysts and has been demonstrated to be a good sorbent for removing sulfur-related compounds at high temperature. [26,27] As a dielectric material, its physical, electrical, and optical properties have been studied for various applications. [21,28,29] In this Communication, we shall demonstrate a three-stage synthesis of twinned Zn 2 TiO 4 nanowires using ZnO nanowires as template, which could be further developed for controlled synthesis of ternary oxide nanostructures. Figure 1a-c shows the scanning electron microscopy (SEM) images of ZnO nanowires and ZnO/Ti core/shell nanowires before and after annealing, respectively. The as-grown ZnO nanowires shown in Figure 1a are randomly aligned, of about 40-60 nm in diameter, and 10 lm in length. It can be seen clearly that the morphology of the ZnO nanowires is reserved after coating with Ti (Fig. 1b). The surface is smooth and the diameter of the Ti-coated nanowires is increased to 70-100 nm. No aggregated Ti particles could be seen in Figure 1b, indicating a uniform deposition of Ti on ZnO ...

Synthesis and Photocatalytic Property of SnO₂/ZnO Nanorod Composites

“…The SnO 2 particles deposited in this way was not dense, as can be seen from the inhomogeneous contrast. This result was line with Sun's work [27].…”

Twin-induced one-dimensional homojunctions yield high quantum efficiency for solar hydrogen generation

“…As a twin plane in ZB structure in the o1114 direction can be considered as a monolayer of WZ structure 25 , it means that a stacking fault in ZB (WZ) can create a segment of WZ (ZB). For example, in the ZB structure, misplacement of a bilayer to yield a sequence of AaBbCcAaCcBbAc results in a symmetry structure with a mirror plan Aa, which is known as a twin plane or twin boundary, whereas the consequent CcAaCc segment can be recognized as a three-bilayer WZ structure 28,35 . Therefore, the appearance of these twin boundaries in nanocrystals can suddenly break the continuity of the ZB lattice constitution and generate a myriad of WZ segments in the ZB lattice.…”

Comparative Study of Room‐Temperature Ferromagnetism in Cu‐Doped ZnO Nanowires Enhanced by Structural Inhomogeneity

“…Recently, similar approaches except with random aligned NWs have also been used to synthesize spinel ZnAl 2 O 4 nanotubes and twined Zn 2 TiO 4 nanowires. [27,28] The good vertical alignment of ZnO NWs on the sapphire substrates facilitated a homogeneous Cu coating on the nanowire sidewalls. In another work, He et al achieved Ni doping by planting metal ions into well-aligned ZnO NWs followed by annealing.…”