Manuputty Manoel Y, Dreyer Jochen A H, Sheng Yuan, Bringley Eric J, Botero Maria L, Akroyd Jethro, Kraft Markus
Department of Chemical Engineering and Biotechnology , University of Cambridge , West Site, Philippa Fawcett Drive , Cambridge , CB3 0AS , UK . Email:
Cambridge Centre for Advanced Research and Education in Singapore (CARES) , CREATE Tower, 1 Create Way , 138602 , Singapore.
Chem Sci. 2018 Nov 14;10(5):1342-1350. doi: 10.1039/c8sc02969e. eCollection 2019 Feb 7.
A metastable "high-pressure" phase known as α-PbO-type TiO or TiO-II is prepared a single-step synthesis using a laminar premixed stagnation flame. Three other TiO polymorphs, namely anatase, rutile and TiO-B phases, can also be obtained by tuning the oxygen/fuel ratio. TiO-II is observed as a mixture with rutile under oxygen-lean flame conditions. To the best of our knowledge, this is the first time that this phase has been identified in flame-synthesised TiO. The formation of TiO-II in an atmospheric pressure flame cannot be explained thermodynamically and is hypothesised to be kinetically driven through the oxidation and solid-state transformation of a sub-oxide TiO intermediate. In this scenario, rutile is nucleated from the metastable TiO-II phase instead of directly from a molten/amorphous state. Mixtures containing three-phase heterojunctions of anatase, rutile, and TiO-II nanoparticles as prepared here in slightly oxygen-lean flames might be important in photocatalysis due to enhanced electron-hole separation.
一种被称为α-PbO型TiO或TiO-II的亚稳“高压”相是通过层流预混驻定火焰一步合成制备的。通过调节氧/燃料比，还可以获得其他三种TiO多晶型物，即锐钛矿、金红石和TiO-B相。在贫氧火焰条件下，TiO-II被观察到与金红石混合存在。据我们所知，这是首次在火焰合成的TiO中鉴定出该相。在大气压火焰中TiO-II的形成无法用热力学解释，据推测是由亚氧化物TiO中间体的氧化和固态转变动力学驱动的。在这种情况下，金红石是从亚稳的TiO-II相形核，而不是直接从熔融/非晶态形核。在此处贫氧火焰中制备的含有锐钛矿、金红石和TiO-II纳米颗粒三相异质结的混合物，由于增强的电子-空穴分离，在光催化中可能很重要。
