Ying Wang,Fei Liu,Mengqin Yao,Jun Ma,Shuo Geng,Jianxin Cao,Xiaodan Wang
Promoting the efficient formation of methanol intermediates during CO 2 hydrogenation to lower olefins plays a decisive role in improving the catalytic performance of a tandem catalyst. In this study, a series of chromium (Cr)-modified gallium–zirconium oxides with the formula GaCrZrO x (y%) were prepared via the sol–gel method. The characterization and experimental results show that the addition of moderate amounts of Cr not only facilitates the formation of more oxygen vacancies on the surface of GaZrO x but also strengthens the adsorption and activation ability of CO 2 and H 2 , thereby promoting the generation of formate and methoxy intermediates. After coupling with SAPO-34 zeolite, the methanol intermediate produced on GaCrZrO x (y%) is rapidly converted into lower olefins. This integration manner oxide and zeolite catalysts is particularly important for catalytic performance because an appropriate affinity between components can induce the formation of methanol intermediates via the kinetic effect, which limits the reverse water–gas shift reaction at high temperature. The GaCrZrO x (3.0 %)/SAPO-34 tandem catalyst synthesized via grinding and mixing at 390 °C and 3 MPa exhibits remarkable stability and catalytic performance, achieving a CO 2 conversion close to 30 %, a lower olefin selectivity of 85.8 %, and a lower olefin yield of 11.7 %.
SiO x is regarded as a promising anode material for the next-generation lithium-ion batteries with high energy density. However, the reduplicative volume changes during cycling cause the pulverizations of Si, leading to decreased utilization of active Si component and poor cycling performance. Herein, a facile and scalable Fe-Cr decorating strategy is reported to boost the lithium storage of SiO x anode. Our comprehensive characterizations indicate that there are strong interactions between Fe-Cr and SiO x during a facile ball milling process. After cycling, Fe-Cr nanoparticles are dispersed in the in-situ formed lithium silicates and Li 2 O matrix, which can maintain superior conductivity of lithium ion and electron for the active components through point-to-point connections. This unique structure boosts the electrochemical de-alloying process of the low-valent Li x Si (0 ≤ x ≤ 2), and increases effective utilization of the active Si component during cycling, resulting in improvement of reversible capacity and cycling stability. This bm SiO x -FeCr electrode can deliver high reversible specific capacity (1370 m Ah g −1 at 200 mA g −1 ), good rate capability (653.8 m Ah g −1 at 2000 mA g −1 ), and superior cycling stability. This work provides a promising route for improving the utilization of active Si component and the structural stability of SiO x -based anodes.
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