Coral-like TiO2−δ microstructures with high surface area were synthesized by a simple hydrothermal method, followed by thermal treatment in a N2 atmosphere. The introduction of oxygen vacancies (OVs) to TiO2 significantly improved light absorption and inhibited the recombination of photogenerated charge carriers. Then, multiwalled carbon nanotubes (CNTs) and N-doped carbon quantum dots (N-CQDs) were decorated on the surface of coral-like TiO2−δ microstructures. The CNTs could greatly improve the separation and transfer efficiency of photogenerated charge carriers, while the N-CQDs could further extend light absorption to longer wavelengths, including the IR region. According to the results of electron spin resonance (ESR) spectroscopy, the introduction of OVs to TiO2−δ and surface modification with CNTs and N-CQDs promoted the generation of •O2– and •OH active species. The formation of •O2– and •OH active species on the surface of TiO2−δ/CNTs/N-CQDs played an important role in the deep oxidation and selective conversion of NO into nitrate. Density functional theory calculations revealed the adsorption and reaction sites for H2O and O2 separately in space over the surface of TiO2−δ/CNTs/N-CQDs. Namely, the reaction sites of H2O and O2 are on the surface of TiO2−δ and CNTs, respectively. The electron transfer from TiO2−δ to CNTs was further verified through the differential charge density. This study demonstrates a straightforward approach for designing full-spectrum-responsive photocatalysts with high efficiency, stability, and selectivity for NO removal.
Hanna He,Qi Zhang,Haiyan Wang,Hehe Zhang,Jiadong Li,Zhiguang Peng,Yougen Tang,Minhua Shao
Inferior electronic conductivity and sluggish sodium ion diffusion are still two big challenges for TiO 2 anode material for Na ion batteries (SIBs). Herein, we synthesize TiO 2 /C composites by the pyrolysis of MIL-125(Ti) precursor and successfully introduce defects to TiO 2 /C composite by a simple magnesium reduction. The as-prepared defect-rich TiO 2-δ /C composite shows mooncake-shaped morphology consisting of TiO 2-δ nanocrystals with an average particle size of 5 nm well dispersed in the carbon matrix. When used as a SIBs anode, the defect-rich TiO 2-δ /C composite exhibits a high reversible capacity of 330.2 mAh g −1 at 50 mA g −1 at the voltage range of 0.001–3.0 V and long-term cycling stability with negligible decay after 5000 cycles. Compared with other four TiO 2 /C samples, the electrochemical performance of defect-rich TiO 2-δ /C is highly improved, which may benefit from the enhanced electronic/ionic conductivities owing to the defect-rich features, high surface area rendering shortened electronic and ionic diffusion path , and the suppress of the TiO 2 crystal aggregation during sodiation and desodiation process by the carbon matrix.
Cen Wang,Xuan Ge,Huiqing Fan,Fan Yang,Qiaodan Hu,Jianguo Li
Oxygen deficient TiO 2- δ nanoparticle has raised wide research interests as electrocatalysts, however, it is challenging to tune the particle size and phase composition simultaneously to optimize its performance. Here we prepared TiO 2- δ nanoparticles taking advantage of the liquid immiscibility phenomenon in TiO 2 -SiO 2 system by aerodynamic levitation (ALD), and employed a simple parameter, the resident time in the immiscibility region, to achieve simultaneous tuning of particle size and phase composition. A quantitative relationship between the particle size and the mass fraction of rutile phase was established, and the formation mechanism of the two-phase particle was proposed. Furthermore, the synthesized TiO 2- δ nanoparticles were evaluated as electrocatalysts for reducing nitrate to ammonia, which showed better performance than the commercial TiO 2 nanopowder. Results from this work provide a simultaneous tuning strategy for regulating the particle size and phase compositions of TiO 2- δ nanoparticles by controllable solidification, and broaden the potential application of TiO 2- δ .
危险品化学品经营许可证（带存储）