Single-crystal-like ZnO mesoporous spheres derived from metal organic framework delivering high electron mobility for enhanced energy conversion and storage performances
A rational solvothermal method is proposed to achieve the conversion from a Zn contented metal organic framework to ZnO mesoporous single-crystal-like spheres. The as-prepared ZnO sphere is composed of oriented assembled primary crystals, which exhibits single crystal nature with narrow pore size distribution and high surface area. In addition, time depending trails indicate the metal organic framework functions as reservoir to control the release of Zn species and the organic molecules also serve as directing regent to facilitate the oriented assembling of the ZnO primary units. Thanks to this structure coherence, the ZnO sphere delivers high electron mobility, which enables reduced carrier recombination and improved collection efficiency of the photoelectrons when used as photoanode in CdS/CdSe sensitized solar cell. The device achieves a high power conversion efficiency of ∼6.20%, which is substantially improved from that of regular ZnO nanoparticles (∼5.02%). Moreover, when evaluated as anode for lithium ion battery, the ZnO sphere based electrode demonstrates high reversible capacity of 1016.7 mA h g −1 at 100 mA g −1 after 100 cycles, and excellent high rate stability which shows impressive reversible capacity of 698.4 mA h g −1 at 1000 mA g −1 after 300 cycles.