Rapid solid-state metathesis route to transition-metal doped titanias

Abstract

Rapid solid-state metathesis (SSM) reactions are often short-lived highly exothermic reactions that yield a molten alkali halide salt that aids in product growth and crystallization. SSM reactions may also produce kinetically stabilized structures due to the short (seconds) reaction times. This report describes the investigation of rapid SSM reactions in the synthesis of transition-metal doped titanias (M-TiO 2). The dopant targeted compositions were ten mol percent and based on elemental analysis, many of the M-TiO 2 samples were close to this targeted level. Based on surface analysis, some samples showed large enrichment in surface dopant content, particularly chromium and manganese doped samples. Due to the highly exothermic nature of these reactions, rutile structured TiO 2 was observed in all cases. The M-TiO 2 samples are visible colored and show magnetic and optical properties consistent with the dopant in an oxide environment. UV and visible photocatalytic experiments with these visibly colored rutile M-TiO 2 powders showed that many of them are strongly absorbent for methylene blue dye and degrade the dye under both UV and visible light illumination. This work may open up SSM reactions as an alternate nonthermodynamic reaction strategy for dopant incorporation into a wide range of oxide and non-oxides.

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

“…69) [430,431]. First-principle calculations showed the appearance of new energy levels in the band gap, which is in agreement with the experimentally observed decrease of apparent band gap and coloration of TiO 2 [432,433]. Based on the enhanced absorption in the visible spectrum thus one may expect that transition metal doped TiO 2 materials in general have better photocatalytic activity than the corresponding pristine TiO 2 .…”

Botanically Templated Monolithic Macrostructured Zinc Oxide Materials for Photocatalysis

“…The run-to-run comparison for ZZ-ZnO showed good consistency with deviations of only a few percent ( Figure S5). Finally, it should be noted that the comm-ZnO powder shows similarly high MB photodegradation to previously examined P25 (primarily anatase) TiO 2 powders in the same photoreactor (~90% MB degradation in 15 min) [44].…”

“…The run-to-run comparison for ZZ-ZnO showed good consistency with deviations of only a few percent ( Figure S5). Finally, it should be noted that the comm-ZnO powder shows similarly high MB photodegradation to previously examined P25 (primarily anatase) TiO2 powders in the same photoreactor (~90% MB degradation in 15 min) [44]. In contrast to the cobalt results, the nickel-doped ZnO samples show less detrimental effect on UV photoactivity, though increasing Ni content led to a decrease in MB dye degradation rate.…”

Microwave Metathesis Synthesis and Characterization of TMPO4 (TM = Cr, Mn, Fe, Co, Ni, Cu)

“…Secondly, pH regulation must be under proper control to overcome the formation of undesirable phases in precipitation method. Last of all, the wet processes take long reaction time, use expensive equipment, possess complicated stages and produce poor yield [22]. There is a method except all of them called microwave metathesis synthesis (MMS) driven by high lattice energy by-product such as NaCl by microwave energy emerging as an alternative method of synthesis of inorganic solids such as vanadates, phosphates, borates [23,24], oxides [25], etc.…”