Well‐Ordered Large‐Pore Mesoporous Anatase TiO₂ with Remarkably High Thermal Stability and Improved Crystallinity: Preparation, Characterization, and Photocatalytic Performance

Abstract

Thermally-stable, ordered mesoporous anatase TiO 2 with large pore size and high crystallinity has been successfully synthesized through an evaporationinduced self-assembly technique, combined with encircling ethylenediamine (EN) protectors to maintain the liquid crystal mesophase structure of TiO 2 primary particles, followed by calcination at higher temperature. The structures of the prepared mesoporous TiO 2 are characterized in detail by small-angle and wide-angle X-ray diffraction, Raman spectra, N 2 adsorption/ desorption isotherms, and transmission electron microscopy. Experimental results indicate that the well-ordered mesoporous structure could be maintained up to 700 ° C (M700) and also possesses large pore size (10 nm), high specifi c BET surface area (122 m 2 g − 1 ), and high total pore volumes (0.20 cm 3 g − 1 ), which is attributed to encircling EN protectors for maintaining the mesoporous framework against collapsing, inhibiting undesirable grain growth and phase transformation during the calcination process. A possible formation mechanism for the highly stable large-pore mesoporous anatase TiO 2 is also proposed here, which could be further confi rmed by TG/FT-IR in site analysis and X-ray photoelectron spectroscopy. The obtained mesoporous TiO 2 of M700 exhibit better photocatalytic activity than that of Degussa P25 TiO 2 for degradation of highly toxic 2,4-dichlorophenol under UV irradiation. This enhancement is attributed to the well-ordered large-pore mesoporous structure, which facilitates mass transport, the large surface area offering more active sites, and high crystallinity that favors the separation of photogenerated electron-hole pairs, confi rmed by surface photovoltage spectra.

Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

“…Fig. 3c shows the N 2 adsorptiondesorption isotherms of the four as-prepared samples are type IV according to the IUPAC classification and indicate the existence of mesopores within the interparticles [41]. The BET specific surface areas of the four samples are slightly changed, indicating no changed in the structure, as shown in the inset of Fig.…”

“…4e) is attributed to the electron transitions from the VB to the conduction band (band-to-band transitions, O2p-Ti3d) [46]. The SPS peak intensity for sample iii is stronger than that of others, illustrating the high-efficient separation of photogenerated electron-hole pairs and long excitation life-times for the former [41]. Both the SPS and transient-state fluorescence results .…”

Carbon coated Au/TiO2 mesoporous microspheres: a novel selective photocatalyst

“…Titania (TiO2) has been regarded as one of the most efficient photocatalysts since the first report by Fujishima and Honda [3][4][5][6], because of its high catalytic activity, good stability and low toxicity. After that, huge progress towards improving the photocatalytic efficiency of TiO2 has been made [7], such as band-tailoring by element doping [8,9], constructing mesoporous and/or array structures [10][11][12][13], and plasmonic sensitizing [14,15]. Nevertheless, TiO2 is generally regarded as non-selective because the degradation of organic compounds on TiO2 is enabled by nonselective oxidizing agents (e.g., OH radical) [16].…”

The Influence of Acids on Tuning the Pore Size of Mesoporous TiO2 Templated by Non‐Ionic Block Copolymers

“…Although the Bragg reflections of the space group are not resolved, the presence of a low angle diffraction peak suggests that the samples possess a semi-organized mesoporous structure with relative uniform pores, but without long range ordering. [19,20] The small shift, toward smaller value of 2θ, in TiO 2 PA1M and TiO 2 NA1M reveals an expansion of the unit cell. [21] Moreover, the diffraction peak of TiO 2 NA1M is somewhat broader.…”