Hybrid materials are attracting intensive attention for their applications in electronics, photoelectronics, LEDs, field-effect transistors, etc. Engineering new hybrid materials and further exploiting their new functions will be significant for future science and technique development. In this work, alternatively stacked self-assembled CoAl LDH/MoS2 nanohybrid has been successfully synthesized by an exfoliation-flocculation method from positively charged CoAl LDH nanosheets（CoAl-NS） with negatively charged MoS2 nanosheets（MoS2-NS）. The CoAl LDH/MoS2 hybrid material exhibits an enhanced catalytic performance for oxygen evolution reaction（OER） compared with original constituents of CoAl LDH nanosheets and MoS2 nanosheets. The enhanced OER catalytic performance of CoAl LDH/MoS2 is demonstrated to be due to the improved electron transfer, more exposed catalytic active sites, and accelerated oxygen evolution reaction kinetics.
Controlling the growth of nanocrystals is one of the most challenged issues in current catalytic field, which helps to further understand the size and morphology related behaviors for catalytic applications. In this work, we investigated the plane growth kinetics of Mg（OH）2 for catalytic application in preferential CO oxidation. Nanoflakes were synthesized through hydrothermal method. The morphology and structure of nanoflakes were characterized by TEM, SEM, and XRD. By varying the reaction temperature and time, Mg（OH）2 nanoflakes un- derwent an anisotropic growth. Benefited from the Ostwald ripening process, the thickness of nanoflake corre- sponding to the （110） plane of Mg（OH）2 was tuned from 7.6 nm to 24.0 nm, while the diameter of （001） plane in- creased from 18.2 nm to 30.2 nm. The grain growth kinetics for the thickness was well described in terms of an equation, D5= 7.65＋ 6.9 × 10^8exp（-28.14/RT）. After depositing Pt nanoparticles onto these Mg（OH）2 nanoflakes, an excellent catalytic performance was achieved for preferential CO oxidation in H2-rich streams with a wide temper- ature window from 140 ℃ to 240 ℃ for complete CO conversion due to the interaction between Pt and hydroxyl groups. The findings reported here would be helpful in discovering novel catalysts for application of proton ex- change membrane fuel cells.
Huixia LiLiping LiShaoqing ChenYuelan ZhangGuangshe Li
MnO/C core-shell nanowires with varying carbon shell thickness were synthesized via calcining resorci- nol-formaldehyde resin（RF） with different amounts of hydrothermally synthesized MnO2 nanowires. The relationship between the carbon shell thickness and the anode performance of the MnO/C materials was discussed. With a suitable carbon shell thickness（6.8 nm）, the MnO/C core-shell nanowires exhibit better cycling and rate performance than those with a smaller or larger thickness. The TEM results show that after 50 cycles, the core-shell structure with this thickness can be retained, which leads to superior performance. This contribution provides a significant guiding model for optimizing the electrochemical performance of MnO/C core-shell materials by controlling the thickness of carbon shells.
Three-dimensional（3-D）saucer-and rod-like WO3 microstructures have been synthesized by a simple hydrothermal route using tartaric acid as the assistant agent.X-ray powder diffraction（XRD）patterns indicate that the as-prepared samples are the pure hexagonal phase WO3.The morphologies are characterized by scanning electron microscope（SEM）and are found to be highly sensitized to the reaction temperature.A probable formation mechanism of the WO3 microstructures from saucer-like at low temperatures to rod-like at high temperatures is proposed.The optical properties of the novel WO3 microstructures are studied by UV-vis diffuse reflectance spectroscopy（DRS）.The mechanism of strong absorption at visible region and red shift of calcined sample is also discussed.
