Qingqing Jiang

Synthesis and characterization of Ni doped SnO2 microspheres with enhanced visible-light photocatalytic activity

Nickel-doped tin dioxide (NDT) microspheres with various doping levels were prepared by hydrothermal synthesis and characterized by using X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy-dispersive spectroscopy analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-vis absorption spectroscopy. The formation mechanism of NDT microspheres was discussed. All samples prepared with different Sn/Ni ratios shows higher photocatalytic activity than that of pure SnO2 and pure NiO under visible light irradiation (λ > 420 nm). The photocatalytic activity is closely related to the composition of as-prepared photocatalysts. It is noted that the NDT microspheres with the doping content of 33.3 mol% exhibit the highest photoactivity. Moreover, this catalyst showed improved stability, and the activity did not weaken significantly after four recycles. The higher activity of NDT microspheres may be attributed to the combined effect of its demonstrated doping levels and appropriate band gap. And the doping of Ni2+ may facilitate the generation of electron and hole pairs and inhibit their recombination rate by acting as temporary trapping sites of photoinduced electrons.

Bi metal-modified Bi4O5I2 hierarchical microspheres with oxygen vacancies for improved photocatalytic performance and mechanism insights

In this work, we firstly synthesized metallic Bi-modified Bi4O5I2 nanocomposites with oxygen vacancies via a facile one-pot solvothermal method. The deposited Bi metal and oxygen vacancies endowed the Bi/Bi4O5I2 samples with dramatically enhanced photocatalytic performance for degradation of bisphenol A (BPA) and methyl orange (MO) under visible light irradiation. In particular, the improved photocatalytic activity can be ascribed to the synergistic effect of Bi metal and oxygen vacancies, which resulted in their efficient light harvesting properties and excellent charge separation ability. The photocatalytic mechanism of Bi/Bi4O5I2 for organics degradation was demonstrated. This work could shed light on exploring high photocatalytic performance materials and stimulating the development of non-noble metal/BixOyIz photocatalysts, which would also contribute to advancement in environmental remediation and energy exploitation.

Synthesis and characterization of single-crystalline Bi2O2SiO3 nanosheets with exposed {001} facets

Bismuth oxide silicate (Bi2O2SiO3) single-crystalline nanosheets with exposed {001} facets were synthesized for the first time via a facile one-step CTAB-assisted hydrothermal method in the presence of NaOH. Control experiments were carried out to investigate various factors that affect the formation, morphology and exposed planes of the products systematically. The results revealed that the pH and the amount of CTAB play vital roles in the reaction. Bi2O2SiO3 nanosheets could not be obtained without the addition of sodium hydroxide solution in the synthesis process, and CTAB not only promotes the exposure of {001} facets, but also modulates the size and thickness of these Bi2O2SiO3 nanosheets in a wide range. It was shown that the as-prepared Bi2O2SiO3 nanosheets synthesized under the conditions that the amount of CTAB was 4 mmol and the pH value was 12 exhibited higher photocatalytic activities toward RhB and BPA degradation under simulated sunlight irradiation than all the other samples in our experiment, which might give the main credit to the highly exposed {001} facets and considerable number of oxygen vacancies. The present work provides a new reference for the synthesis of Bi2O2SiO3 nanosheets and other manipulation of facet-dependent photoreactivity of semiconductors.

Construction of Hierarchical MoSe2 Hollow Structures and Its Effect on Electrochemical Energy Storage and Conversion

Metal selenides have attracted increased attention as promising electrode materials for electrochemical energy storage and conversion systems including metal-ion batteries and water splitting. However, their practical application is greatly hindered by collapse of the microstructure, thus leading to performance fading. Tuning the structure at nanoscale of these materials is an effective strategy to address the issue. Herein, we craft MoSe2 with hierarchical hollow structures via a facile bubble-assisted solvothermal method. The temperature-related variations of the hollow interiors are studied, which can be presented as solid, yolk-shell, and hollow spheres, respectively. Under the simultaneous action of the distinctive hollow structures and interconnections among the nanosheets, more intimate contacts between MoSe2 and electrolyte can be achieved, thereby leading to superior electrochemical properties. Consequently, the MoSe2 hollow nanospheres prepared under optimum conditions exhibit optimal electrochemical activities, which hold an initial specific capacity of 1287 mA h g-1 and maintain great capacity even after 100 cycles as anode for Li-ion battery. Moreover, the Tafel slope of 58.9 mV dec-1 for hydrogen evolution reaction is also attained.

Biomimetic Structure Design and Construction of Cactus-like MoS2/Bi19Cl3S27 Photocatalyst for Efficient Hydrogen Evolution

Cacti grown in arid areas have developed intrinsic water management systems, inspired by the cactus which has survived cruel natural selection, uncommon cactus-like MoS2/Bi19Cl3S27 heterostructures have been successfully constructed in this work. Resembling the trichome and epidermis of a cactus stem, vertically aligned MoS2 along with a carbon species hydrolyzed from glucose on Bi19Cl3S27 comprised the unique biomimetic structure. During the photocatalytic process of MoS2/Bi19Cl3S27 heterostructures, the characteristic biomimetic structure endows the heterostructures with greatly enhanced light adsorption and charge separation capabilities, the whole hydrogen evolution reaction was boosted by the combination of optimized charge and mass transfer paths, like the plant morphogenesis of a cactus which plays a significant role in mucilage-based energy-transmission. As a consequence, the improved photocatalytic H2 evolution rate reaches up to 876.6 μmol g−1 h−1 with an optimal loading of 5 wt% MoS2. The successful preparation of biomimetic structured MoS2/Bi19Cl3S27 samples with good stability shows that bismuth-based materials have great potential for applications in energy conversion systems, while providing enlightenment for the design of other biomimetic structured nanomaterials.