Metal–organic frameworks(MOFs) are of great interest as potential electrochemically active materials.However, few studies have been conducted into understanding whether control of the shape and components of MOFs can...Metal–organic frameworks(MOFs) are of great interest as potential electrochemically active materials.However, few studies have been conducted into understanding whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demonstrate a solvothermal method to realize nanostructure engineering of 2D nanoflake MOFs. The hollow structures withNi/Co-and Ni-MOF(denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemical performance optimizations in supercapacitors and in the oxygen reduction reaction(ORR). As a result, the Ni/CoMOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g^(-1)at 0.5 A g^(-1)in1 M LiO H aqueous solution, much higher than that of NiMOF(306.8 F g^(-1)) and ZIF-67(168.3 F g^(-1)), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the significant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for optimizing energy storage and conversion devices.展开更多
The microstructures and growth process characteristics precipitation-crystallization method were investigated by SEM, TEM of spherical Ni（OH）2 particles synthesized by the aqueous and XRD, and their growth mechanism...The microstructures and growth process characteristics precipitation-crystallization method were investigated by SEM, TEM of spherical Ni（OH）2 particles synthesized by the aqueous and XRD, and their growth mechanism was discussed. With the reaction beginning and continuing, amorphous Ni（OH）2 nano-crystallites grow up to spherical micron-particles with radially arranged crystallites. The nucleation, crystallization and re-crystallization led by Ostwald ripening simultaneously take place through the whole growth processes. With the course from reversible aggregation to irreversible agglomeration, the Ni（OH）2 particles tend to grow according to the template growth model： the growth on the crystallite templates stretching in the radius directions is free and quick, while the growth rate for crystallites in other directions is confined due to lower monomers concentration and tends to dissolve So it is only the radially arranged crystallites that predominate in the particle and lead to characteristic microstructures.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21571157, U1604123, and 51473149)Outstanding Young Talent Research Fund of Zhengzhou University (1521320001)+1 种基金the Open Project Foundation of Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) (2017–29),Nankai UniversityOpen Project Foundation of Key Laboratory of Inorganic Synthesis and Preparation of Jilin University
文摘Metal–organic frameworks(MOFs) are of great interest as potential electrochemically active materials.However, few studies have been conducted into understanding whether control of the shape and components of MOFs can optimize their electrochemical performances due to the rational realization of their shapes. Component control of MOFs remains a significant challenge. Herein, we demonstrate a solvothermal method to realize nanostructure engineering of 2D nanoflake MOFs. The hollow structures withNi/Co-and Ni-MOF(denoted as Ni/Co-MOF nanoflakes and Ni-MOF nanoflakes) were assembled for their electrochemical performance optimizations in supercapacitors and in the oxygen reduction reaction(ORR). As a result, the Ni/CoMOF nanoflakes exhibited remarkably enhanced performance with a specific capacitance of 530.4 F g^(-1)at 0.5 A g^(-1)in1 M LiO H aqueous solution, much higher than that of NiMOF(306.8 F g^(-1)) and ZIF-67(168.3 F g^(-1)), a good rate capability, and a robust cycling performance with no capacity fading after 2000 cycles. Ni/Co-MOF nanoflakes also showed improved electrocatalytic performance for the ORR compared to Ni-MOF and ZIF-67. The present work highlights the significant role of tuning 2D nanoflake ensembles of Ni/Co-MOF in accelerating electron and charge transportation for optimizing energy storage and conversion devices.
基金Project(50134020) supported by the National Natural Science Foundation of ChinaProject supported by Postdoctoral Fund of Central South University
文摘The microstructures and growth process characteristics precipitation-crystallization method were investigated by SEM, TEM of spherical Ni（OH）2 particles synthesized by the aqueous and XRD, and their growth mechanism was discussed. With the reaction beginning and continuing, amorphous Ni（OH）2 nano-crystallites grow up to spherical micron-particles with radially arranged crystallites. The nucleation, crystallization and re-crystallization led by Ostwald ripening simultaneously take place through the whole growth processes. With the course from reversible aggregation to irreversible agglomeration, the Ni（OH）2 particles tend to grow according to the template growth model： the growth on the crystallite templates stretching in the radius directions is free and quick, while the growth rate for crystallites in other directions is confined due to lower monomers concentration and tends to dissolve So it is only the radially arranged crystallites that predominate in the particle and lead to characteristic microstructures.
