Multiple heterojunction system of Bi2MoO6/WO3/Ag3PO4 with enhanced visible-light photocatalytic performance towards dye degradation

Multiple heterojunction system of Bi₂MoO₆/WO₃/Ag₃PO₄ was designed via constructing binary heterojunction Bi₂MoO₆/WO₃, followed by the deposition of nano-Ag₃PO₄ on the surface of Bi₂MoO₆/WO₃. Various techniques were employed to characterize the properties of the as-prepared catalytic system. In this study, the decomposition efficiency of C.I. reactive blue 19 (RB-19) was used as a measure of photocatalytic activity and the Bi₂MoO₆/WO₃/Ag₃PO₄ composite exceeded its stand-alone components (pristine Ag₃PO₄, WO₃/Ag₃PO₄ and Bi₂MoO₆/Ag₃PO₄) by 3.16 times, 2.63 times and 1.75 times, respectively. The photocatalytic tests implied that the construction of multiple heterojunction could achieve efficient separation of photo-generated electrons and holes. A possible photocatalytic mechanism for Bi₂MoO₆/WO₃/Ag₃PO₄ system was also proposed according to the results of trapping experiments.     

Synthesis of porous nanododecahedron Co3O4/C and its application for nonenzymatic electrochemical detection of nitrite

Porous nanododecahedron of Co₃O₄/C has been synthesized by calcination of the ZIF-67 in air at 400 °C and then be used as electrode material for fabricating a highly sensitive and low overpotential sensor of nitrite ion (NO₂^?). The structure and morphology characterization show that ZIF-67 behaves as an ideal sacrificial template for preparing Co₃O₄/C with regular shape. The two components of Co₃O₄ and carbon are uniformly distributed in the composite. Electrochemical analysis shows that the excellent electrocatalysis performance toward the oxidation of NO₂^? is based on the synergy of Co₃O₄ and carbon in the nanocomposite. At NO₂^? concentration from 2 nM to 8 mM, a fast response time within 3 s is revealed and 1.21 nM of detection limit is achieved. The sensor is also reliable to analysis of NO₂^? existed in the real samples of soil leaching liquid and macrophage supernate.     

Mechanochemical synthesis of BiSI and Bi19S27I3 semiconductor materials

With regard to the intensive investigations of bismuth oxyhalides as promising photocatalysts, much expectation may be put on the corresponding chalcohalides but little is known due to difficulty in the synthesis. In this report, BiSI and Bi₁₉S₂₇I₃ were synthesized by one-step mechanochemical method without heating and aqueous operations and the products were characterized by X-ray diffraction crystallography, Raman spectroscopic analysis, X-ray photoelectron spectroscopy analysis, photoluminescence spectra and UV–visible DRS. The new method allowed the simple syntheses of pure bismuth chalcohalides without observable existences of impurity phases. The crystal structures of BiSI and Bi₁₉S₂₇I₃ were orthorhombic, with the absorption band gaps of 1.80 and 1.14 eV for BiSI and Bi₁₉S₂₇I₃, respectively. Bi-rich compound is considered to be beneficial to the photochemical property of chalcohalides. After overcoming the difficulty in the synthesis, our research would offer new strategy to exploit the potentials of V-VI-VII compounds, particularly of sulfides, as promising semiconductors to compete the corresponding counterparts of oxides.     

Syngas production via coal char-CO2 fluidized bed gasification and the effect on the performance of LSCFN//LSGM//LSCFN solid oxide fuel cell

Fluidized bed reactor is widely used in coal char-CO_2 gasification. In this work, the production of syngas by using a fluidized bed gasification technique was first investigated and then the effect of the produced syngas on the performance of the solid oxide fuel cell with a configuration of La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)//La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17)O_(3-δ)//La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)(LSCFN//LSGM//LSCFN)was studied. During the syngas production, we found that the volume fraction of CO increased with the increment of gasification temperature, and it reached a maximum value of 88.8%, corresponding to a composition of 0.76% H_2, 88.8% CO, and 10.44% CO_2, when the ratio of oxygen mass flow rate to that of coal char(MO2/Mchar) increased to 0.29. In the following utilization of the produced syngas in solid oxide fuel cells, it was found that the increasing CO volume fraction in the syngas results in a gradual increase of the peak power density of the LSCFN//LSGM//LSCFN cell. The maximum peak power density of 410 m W/cm~2 was achieved for the syngas produced at 0.29 of M_(O2)/M_(char). In the stability test, the cell voltage decreased by 4% at a constant current density of 0.475 A/cm~2 after 54 h when fueled with the syngas with the composition of 0.76% H2, 88.8% CO, and 10.44% CO_2.It reveals that a carbon deposition with the content of 13.66% in the anode is attributed to the cell performance degradation.     

Effect of temperature-related factors on densification,microstructure and mechanical properties of powder metallurgy TiAl-based alloys

In the present work, the influence of temperature-related factors, including sintering temperature, heating step and temperature-control mode, on the densification, microstructure and mechanical properties of Ti-46.5Al-2.15Cr-1.90Nb-(B, Y, Mo) alloys prepared by SPS has been investigated and discussed in detail. The results obviously indicate that the sintering temperature plays a key role on densification and phase transition, when compared with the heating step and temperature-control mode. Based on the experimental results and theoretical analysis, the densification process and microstructural evolution of TiAl-based alloys during sintering are studied. Moreover, the mechanical properties of the sintered alloys are determined by the combined effects of the densification and microstructure. The obtained results will help to optimize the microstructure and properties for this kind of intermetallic alloys through controlling sintering parameters during powder metallurgy process.