Fang Wenzhang, Khrouz Lhoussain, Zhou Yi, Shen Bin, Dong Chunyang, Xing Mingyang, Mishra Shashank, Daniele Stéphane, Zhang Jinlong
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, School of Chemistry and Chemical Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, P. R. China.
Phys Chem Chem Phys. 2017 May 31;19(21):13875-13881. doi: 10.1039/c7cp01212h.
The preparation of reduced TiO photocatalysts with high Ti concentration is a great challenge due to their instability in air. Here we report a new approach for the synthesis of reduced TiO with {001} facets exposed via a hydrothermal process. By the introduction of fluoride atoms, {001} and {101} facets are formed, which act as hole and electron collectors, respectively, for charge separation. By adjusting the volume of HF added, a rutile-anatase transition is observed for the first time. EPR spectra confirm the generation of Ti species in the bulk of TiO, and Ti signals are studied in the anatase and rutile phases separately. The quantified EPR shows that reduced TiO samples present 14 000-fold more spins compared to the pristine TiO, and the intensity can reach as high as 24.6 × 10 spins per g. The obtained samples also have a unique disordered layer with a thickness of 1-2 nm on their surfaces, which contributes to the stabilization of the formed Ti species by preventing their oxidation in air. In addition, the synthesized reduced TiO samples also exhibit wide-spectrum solar light absorption, especially in the near-infrared region. Owing to their enhanced solar light absorption, improved electron-hole separation and special facet exposure, these samples exhibit enhanced photocatalytic CO reduction performance and high CH selectivity under solar light irradiation, in the absence of a noble metal Pt as a co-catalyst.
制备具有高钛浓度的还原态二氧化钛光催化剂是一项巨大挑战，因为它们在空气中不稳定。在此，我们报道一种通过水热法合成暴露{001}面的还原态二氧化钛的新方法。通过引入氟原子，形成了{001}面和{101}面，它们分别作为空穴和电子收集器用于电荷分离。通过调节添加的氢氟酸体积，首次观察到金红石 - 锐钛矿转变。电子顺磁共振（EPR）光谱证实了在二氧化钛体相中生成了钛物种，并分别在锐钛矿相和金红石相中研究了钛信号。定量EPR表明，与原始二氧化钛相比，还原态二氧化钛样品的自旋数多14000倍，强度可达每克高达24.6×10个自旋。所获得的样品在其表面还具有厚度为1 - 2纳米的独特无序层，通过防止其在空气中氧化有助于所形成钛物种的稳定。此外，合成的还原态二氧化钛样品还表现出宽光谱太阳光吸收，特别是在近红外区域。由于它们增强的太阳光吸收、改善的电子 - 空穴分离和特殊的晶面暴露，这些样品在太阳光照射下，在没有贵金属铂作为助催化剂的情况下，表现出增强的光催化一氧化碳还原性能和高甲烷选择性。
