Highly crystalline mesoporous anatase TiO2nanospheres with high surface area (higher than P25 and anatase TiO2) are prepared by a soft-template method. Despite the high specific surface area, these samples have three times lower equilibrium adsorption (<2%) than Degussa P25. The rate constant of the mesoporous anatase TiO2(0.024 min−1) reported here is 364% higher than that of P25 (0.0066 min−1), for the same catalytic loading. The results of oxidation-extraction photometry using several reactive oxygen species (ROS) scavengers indicated that mesoporous anatase TiO2generates more ROS than P25 under UV-light irradiation. This significant improvement in the photocatalytic performance of mesoporous spherical TiO2arises from the following synergistic effects in the reported sample: (i) high surface area; (ii) improved crystallinity; (iii) narrow pore wall thicknesses (ensuring the rapid migration of photogenerated carriers to the surface of the material); and (iv) greater ROS generation under UV-light.Keywords:mesoporous anatase TiO2;high surface area;photocatalytic
Yuanzhi Min,Gao Song,Ling Zhou,Xinyue Wang,Pingying Liu,Jumei Li
Nanostructured noble metal-semiconductor materials have been attracting increasing attention because of their broad application in the field of environmental remediation, sensing and photocatalysis. In this study, a facile approach for fabricating silver@mesoporousanataseTiO2(Ag@mTiO2) core-shell nanoparticles employing sol-gel and hydrothermal reaction is demonstrated. The Ag@mTiO2nanoparticles display excellent surface-enhanced Raman scattering (SERS) sensitivity and they can detect the methylene blue (MB) molecules with the concentration of as low as 10−8M. They also exhibit outstanding photocatalytic activity compared with mTiO2, due to the efficient separation and recombination restrain of electron–hole pairs under ultraviolet light. The Ag@mTiO2nanoparticles also present good stability and they can achieve recyclable photocatalytic degradation experiments for five times without loss of activity. Subsequently, the nanoparticles with dual functions were successfully used to in situ monitor the photodegradation process of MB aqueous solution. These results, demonstrating the multifunctional Ag@mTiO2nanoparticles, hold promising applications for simultaneous SERS analysis and the removal of dye pollutants in environmental field.Keywords:photocatalytic degradation;surface-enhanced Raman scattering;TiO2;Ag nanoparticle;core-shell
There are few reports on mesoporous anatase TiO2 nanosheets being synthesized without additives and ex situ templates under mild conditions. In this study, mesoporous single-grain layer anatase (MSGLA) TiO2 nanosheets were first synthesized in situ without additives in a new methanol–tetrabutyl titanate (TBT) system on a large scale using a simple and easily reproducible method. The formation mechanism of the MSGLA TiO2 nanosheets was investigated in detail. The results suggest that MSGLA TiO2 nanosheets can be obtained after a simple thermal treatment of amorphous TiO2 sheets that are converted in situ from the precursor Ti(OC4H9)4−n(OCH3)n (1 ≤ n ≤ 4) (TBM), which is gained easily via the transesterification reactions of TBT and anhydrous methanol at room temperature. Moreover, the MSGLA TiO2 nanosheets were applied successfully as anode materials for Li-ion batteries (LIB) and exhibited a discharge capacity of ∼73 mA h g−1 with obvious voltage plateaus over 4000 cycles (a test time of ∼50 days) at 5 C (1 C = 170 mA g−1) and Coulombic efficiencies of each cycle approaching 100%, highlighting them as promising materials for long-term LIB.
Employing TiO 2 as a gas sensing material is advantageous owing to its excellent hydrogen surface receptiveness and stability under extreme conditions. However, their commercial applications are constrained by limited operating temperature range (150–400 °C) and poor selectivity. In this work, we demonstrate that the ordered mesoporous structured TiO 2 is highly favourable for room temperature hydrogen sensing. The sensors prepared with evaporation induced self-assembly (EISA) showed best response ~2.98 × 10 2 toward 1000 ppm H 2 at room temperature with a sensitivity of ~4.6 ± 1.5 × 10 6 ohm/ppm. Moreover, the sensor showed a response time of ~85 s (recovery time of ~198 s) with full baseline recovery and a selectivity factor of ~290 to 1000 ppm of interfering reducing gases CO and CH 4 at room temperature. With a power consumption of ~1 × 10 −9 W the sensors are incredibly suitable for practical applications. We performed XRD, SEM, TEM, XPS, BET and PL characterization not only to confirm the crystal structure, morphology at nanoscale, surface chemical identification, specific surface area, pore size and photo-generated charge species that contribute to the electronic transport properties but sensing mechanism also.
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