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
Alloys based on non-noble metals could be the next generation of high-performance catalysts for many chemical reactions. However, precisely composition controlled synthesis of non-noble alloys remains a significant challenge. In this work, we report a simple synthesis of Cu_（0.5）Ni_（0.5） alloys without any component segregation. Its success relies on the use of Cu–Ni oxalate precursors, which are chelated in the proximity by oxalate ligands. One of the attractive features for the oxalate routes of catalyst preparation is that no classical support material is needed. The actual component ratios of the obtained Cu_（0.5）Ni_（0.5） alloy are consistent with the initial ratio. Cu_（0.5）Ni_（0.5） alloy shows a higher catalytic activity than pure Cu and Ni catalysts in the reduction of p-nitrophenol（4-NP） to p-aminophenol（4-AP） by sodium borohydride（NaBH4） in an aqueous solution, and the performance depends strongly on the strong interaction between Cu and Ni. The findings reported here are highly helpful to understand the relationship between the synergistic effects in alloys and their catalytic performance, and therefore could provide appropriate strategies to obtain desirable catalysts with improved activity in various catalytic applications.
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.
