Xiaolei Sun,Meiyi Jing,Hong Dong,Wenhe Xie,Feng Luo
Transition metal oxides are said to have the ability to enhance the gravimetric capacity of lithium-ion batteries by two or three times that of current state-of-the-art graphite anodes. Recent reports have demonstrated that the combined utilization of structural architecture and surface modification is an attractive strategy to improve lithium storage capability. In this study, novel CuO-ZnO@Al 2 O 3 submicroflakes were prepared by magnetron sputtering deposition of Cu-Zn alloy films on a removable sacrificial substrate, followed by a facile thermal oxidation treatment and Al 2 O 3 coating procedure by particle atomic layer deposition. They combine the advantages of CuO-ZnO submicroflakes, such as high lithium storage capability and fast lithium ion transportation, and Al 2 O 3 nano-coating with effective protection of the electrode interface during cycling. When utilized as anode materials for LIBs, the CuO-ZnO@Al 2 O 3 submicroflakes exhibit superior specific capacity, enhanced cycling stability, and outstanding rate capability compared with pristine CuO-ZnO submicroflakes, commercial CuO and ZnO powders. The CuO-ZnO@Al 2 O 3 submicroflakes electrodes deliver a high reversible capacity of 814 mAh g −1 at a current density of 50 mA g −1 , and still maintain a moderate capacity of 447 mAh g −1 at a high current density of 1000 mA g −1 . Pairing with a commercial LiFePO 4 cathode, full cell shows high capacity retention and stable cycling performance, suggesting the feasibility of the CuO-ZnO@Al 2 O 3 submicroflakes in practical energy storage applications. In addition, our findings also provide a clear proof-of-concept of the surface coating technique, which might be applied widely to other materials and devices where nano-coating produces desirable properties.
CO2hydrogenation to methanol was conducted using a set of activated carbon-supported Cu/ZnO/Al2O3catalysts (CCZA) prepared by an incipient wetness impregnation approach. The effect of the Cu/Al ratio on the physicochemical properties of the catalysts, as well as their catalytic performance, were investigated. As Cu/Al ratio increased, the metallic Cu surface area displayed a reducing trend from 6.88 to 4.18 m2∙gcat−1, while the CO2adsorption capacity exhibited an increasing trend. Meanwhile, aluminum content will have an important effect on the catalysts’ reducibility and, thus, on their catalytic performance. The CCZA-2.7-de catalyst demonstrated the highest selectivity to methanol at 83.75% due to the excellent distribution and synergistic effect of copper and zinc. Although the CO2conversion of CCZA-2.2-de and CCZA-3.5-de exceeded 10%, the CH3OH selectivity was less than 60%, which may be attributed to the larger particle sizes of ZnO and poor interactions in Cu–Zn. The present study offers a novel approach to increase the number of active sites, optimize the activated carbon-aided Cu/ZnO/Al2O3catalyst’s composition, and finally elucidate the mechanism for CO2hydrogenation to methanol.Keywords:CO2hydrogenation;CuO/ZnO/Al2O3catalyst;methanol synthesis;carbon-supported catalyst;thermocatalysis
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