Crystallization and Phase-Transition Characteristics of Sol−Gel-Synthesized Zinc Titanates

Abstract

Semiconductor research has recently shown great promise recently in areas such as hydrogen production through photocatalytic water splitting, 1 dye-sensitized solar cells, 2 and photocatalytic remediation of harmful organics from air and water. 3,4 Of the semiconductors investigated, titanium dioxide (TiO 2 ) has received the most attention, because of its excellent stability, nontoxicity, cost, and availability, as well as its ability to produce highly oxidizing radicals. 5,6 Zinc oxide (ZnO) has also shown promise in the areas of solar cells, 7 gas sensors, 8,9 and photocatalysis. 10 The simultaneous synthesis of a ZnO-TiO 2 composite usually results in the formation of one or more of the three known compounds from the ZnO-TiO 2 system: Zn 2 TiO 4 (zinc orthotitanate), with a cubic spinel crystal structure; Zn 2 Ti 3 O 8 , with a cubic defect spinel structure; and ZnTiO 3 (zinc metatitanate), with a rhombohedral ilmenite structure. 11-14 Zn 2 Ti 3 O 8 is the metastable, low-temperature (<820 °C) form of ZnTiO 3 ; 14 however, pure ZnTiO 3 is not easily obtained, because it transforms to Zn 2 TiO 4 and rutile. 12,13 Zinc orthotitanate (Zn 2 TiO 4 ) is an inverse spinel that has been used as a catalyst and a pigment. 15 As a catalyst, ZnTiO 4 is used as a sorbent for the removal of sulfur from coal gasification product gases, in hot gas desulfurization units, at temperatures in the range of 400-700 °C. Zinc orthotitanate can easily withstand these temperatures, but it is also one of the leading regenerable catalysts. [15][16][17][18][19][20][21] Zn 2 TiO 4 may also be used for the photocatalytic

Dye sensitized solar cell applications of CdTiO3–TiO2 composite thin films deposited from single molecular complex

“…The two broad peaks at 610 and 634 cm À 1 characteristic of anatase and rutile phases respectively are super imposed by the broad intense peak of CdTiO 3 at 610 cm À 1 . These results accord well with our XRD pattern and are also in agreement with the previously reported Raman data for CdTiO 3 [49] and TiO 2 [50,51] phases. Fig.…”

Synthesis and high (pressure, temperature) stability of ZnTiO3 polymorphs studied by Raman spectroscopy

“…There have been attempts to obtain pure Il-ZnTiO 3 employing several procedures. The ceramic method after a mechanochemical pretreatment of the starting materials [6,7] is currently the most used, but a Sol-Gel process has also been employed to produce zinc titanates [8], as well as the "soft synthesis" route [9], the Pechini process [10] or the molten salt synthesis method [11]. Despite the large number of methods used to obtain pure Il-ZnTiO 3 , its preparation is still a challenge in materials chemistry since ZnTiO 3 decomposes into Zn 2 TiO 4 and TiO 2 at~1223 K [12].…”

Theoretical and experimental investigation into photoelectrocatalytic oxidation and reduction property of ZnFeTi mixed metal oxides

“…(1 1 3) were all observed in the curve of ZnFeTi-LDHs, confirming the formation of typical LDH material [22][23][24]. Moreover, comparing with the XRD patterns of original LDH material and TiO 2 , the curve of MMO showed the complete destruction of layered structure of ZnFeTi-LDHs and appears the peaks of ZnO, Fe 2 O 3 and TiO 2 , which indicated the formation of ZnFeTi mixed metal oxides [25][26][27]. In addition, Table 1 The SEM and TEM images of ZnFeTi-LDHs and MMO are given in Fig.…”