通常报道的煅烧策略通常需要高温才能使金属有机骨架(MOFs)颗粒开裂,这往往会导致纳米材料无法控制的生长。这里,第一次,我们利用电化学阴离子交换方法来控制MOFs的水解并合成多孔Ni/Co氢氧化物纳米片。电化学阴离子交换后,MOFs纳米片的有机配体可以回收再利用。在碱性溶液中向MOFs本体施加电场可以加速氢氧化物的成核速率并改变带电离子/分子的迁移行为。可以定制衍生物的微观结构,提高电极的深度充放电能力。因此,优化的Ni:Co摩尔比为7:3,电场施加时间为1000次循环[Ni0.7Co0.3(OH)2-1000c]的氢氧化物比没有电场辅助合成的材料具有更好的电化学性能:2115Cg-1(4230Fg-1)的高比电容。具有Ni0.7Co0.3(OH)2-1000c电极的混合超级电容器显示出74.7Whkg-1的高能量密度,提高了功率密度(5,990.6Wkg-1),和优异的循环稳定性(8,000个循环)。本研究不仅为低成本的制备提供了新的策略,用于超级电容器的深放电电极,但也提出了一种非常规的方法,用于将MOFs材料温和地合成为具有定制的微观形态的多孔纳米级衍生物。
The commonly reported calcination strategy usually requires high temperature to crack the metal-organic frameworks (MOFs) particles, which often lead to uncontrollable growth of nanomaterials. Here, for the first time, we utilize an electrochemical anion-exchanged method to control the hydrolysis of MOFs and synthesize porous Ni/Co
hydroxide nanosheets. After the electrochemical anion-exchange, the organic ligands of MOFs nanosheets can be recycled and reused. Applying an electric field to the MOFs bulk in alkaline solution can accelerate the nucleation rate of
hydroxide and change the migration behavior of charged ions/molecules, which can tailor the microstructure of derivatives and improve deep charge and discharge capability of the electrodes. As a result, the
hydroxide with the optimized Ni:Co molar ratio of 7:3 and electric-field application time of 1000 cycles [Ni0.7Co0.3(OH)2-1000c] provides much better electrochemical properties than the materials synthesized without electric-field assistance: a high specific capacitance of 2115C g-1 (4230F g-1). A hybrid supercapacitor with the Ni0.7Co0.3(OH)2-1000c electrode shows a high energy density of 74.7 Wh kg-1, an improved power density (5,990.6 W kg-1), and an excellent cyclic stability (8,000 cycles). This study not only provides a novel strategy for the preparation of low-cost, deep-discharge electrodes for supercapacitors, but also proposes an unconventional method for mild synthesizing MOFs materials into porous nanoscale derivatives with tailored micromorphology.