Gayathri Sampath, Arunkumar Paulraj, Saha Dipankar, Han Jong Hun
School of Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 61186, Republic of Korea.
Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo, Norway.
J Colloid Interface Sci. 2021 Apr 15;588:557-570. doi: 10.1016/j.jcis.2020.11.129. Epub 2020 Dec 10.
The fabrication of interpenetrated heterostructures from desirable energy materials for the development of efficient supercapacitors is promising yet challenging. Herein, a leaf-shaped cobalt phosphide/cobalt oxide heterostructure, (CoP)/CoO (0.44 > y > 0.06), was synthesized from 2D-zeolitic-imidazolate-framework (ZIF-Co-L) molecular precursor via phosphidation of the CoO intermediate. The efficient construction of heterostructure through the variation of surface/bulk composition significantly alters the interfacial properties and electronic structure, yielding enhanced supercapacitor performance. Further, gas-phase phosphidation entails a core-shell formation mechanism via gas diffusion, regulated by the Kirkendall effect. The optimized heterostructure (y = 0.10) exhibits remarkable interfacial properties derived from the CoO/Co/CoP interface, thus facilitating a high specific capacitance (467 F g at 5 A g) and excellent cycling stability (91% after 10000 cycles) at 30 A g. A further increase in the cyclability (107%) was achieved by employing a graphene hybrid. Further, an asymmetric supercapacitor device was fabricated, that delivers reasonably high energy density of 12.7 Wh kg at a power density of 370 W kg and cycling stability of ~93% after 10000 cycles. This study reports on the modulation of interfacial properties of CoP/CoO heterostructure to enhance energy storage performance via bulk/surface compositional variation, thereby providing a strategy to develop heterostructure electrodes for high-performance supercapacitor.
利用理想的能量材料制备互穿异质结构以开发高效超级电容器具有前景但也具有挑战性。在此，通过二维沸石咪唑框架（ZIF-Co-L）分子前驱体经CoO中间体的磷化反应合成了叶状磷化钴/氧化钴异质结构（CoP）/CoO（0.44 > y > 0.06）。通过改变表面/体相组成有效构建异质结构显著改变了界面性质和电子结构，从而提高了超级电容器性能。此外，气相磷化通过气体扩散导致核壳形成机制，受柯肯达尔效应调控。优化后的异质结构（y = 0.10）表现出源自CoO/Co/CoP界面的显著界面性质，因此在30 A g时具有高比电容（5 A g时为467 F g）和优异的循环稳定性（10000次循环后约91%）。通过采用石墨烯杂化物实现了循环稳定性的进一步提高（约107%）。此外，制备了一种不对称超级电容器器件，其在370 W kg的功率密度下提供12.7 Wh kg的合理高能量密度，10000次循环后循环稳定性约为93%。本研究报道了通过体相/表面组成变化调节CoP/CoO异质结构的界面性质以提高储能性能，从而为开发用于高性能超级电容器的异质结构电极提供了一种策略。
