Assembling Hollow Cobalt Sulfide Nanocages Array on Graphene-like Manganese Dioxide Nanosheets for Superior Electrochemical Capacitors

Abstract

Metal-organic framework (MOF)-derived hollow cobalt sulfides have attracted extensive attention due to their porous shell that provides rich redox reactions for energy storage. However, their ultradispersed structure and the large size of MOF precursors result in relatively low conductivity, stability, and tap density. Therefore, the construction of an array of continuous hollow cages and tailoring of the inner cavity of MOF-derived materials is very effective for enhancing the electrochemical performance. Herein, we in situ assembled small Co-based zeolitic imidazolate framework (ZIF-67) on the both sides of negatively charged MnO nanosheets to fabricate a hierarchical sandwich-type composite with hollow cobalt sulfide nanocages/graphene-like MnO. The graphene-like MnO nanosheets acted not only as a structure-directing agent to grow a ZIF-67 array but also as a promising electroactive material of electrochemical capacitors to provide capacitance. As an electrode material of supercapacitors, the as-prepared composites exhibit high specific capacitance (1635 F g at 1 A g), great rate performance (reaching 1160 F g at 10 A g), and excellent cycling stability (80% retention after 5000 cycles). The outstanding electrochemical properties of our designed materials can be attributed to the unique nanostructure that improved electrical conductivity, created more reactive active sites, and increased the diffusion pathway for electrolyte ions.

A Zinc Cobalt Sulfide Nanosheet Array Derived from a 2D Bimetallic Metal–Organic Frameworks for High‐Performance Supercapacitors

“…The electrode is the key component to build an efficient device. The composition and microstructure of electrode materials have a pronounced influence on the properties of an SC . Therefore, significant efforts have been devoted to constructing various electrode materials for supercapacitors.…”

“…The composition and microstructure of electrode materials have ap ronounced influence on the properties of an SC. [2] Therefore, significant efforts have been devoted to constructing various electrode materials for supercapacitors. Carbon, [3] transition metal oxides [4] /hydroxides [5] andc onductive polymers [6] are the most popular materials used in SCs.…”

A Novel Hydrogen Peroxide Amperometric Sensor Based on Hierarchical 3D Porous MnO2−TiO2 Composites

“…The Mn 2p core‐level spectrum (Figure c) shows two distinct peaks at binding energies of 640.8 eV for Mn 2p 2/3 and 652.6 eV for , which were further deconvoluted into two pairs of doublets peaks at 642.5/653.4 and 640.6/652.1, corresponding to the Mn(IV) and Mn(III) species, respectively. This result indicates the presence of a mixed‐valence manganese oxide phase, which is in agreement with the XPS data for MnO 2 reported in the literature .…”

Core‐Shell Structured Cobalt Sulfide/Cobalt Aluminum Hydroxide Nanosheet Arrays for Pseudocapacitor Application

“…The corresponding Nyquist plot (Figure S10) was obtained at an open‐circuit potential of 0.3 V and measured to provide the detailed mechanism of high specific capacity, large rate capability, and excellent stability of sulfide‐modified electrodes. Typically, a small diameter of the semicircle in the high‐frequency region corresponds to a small charge‐transfer resistance of electrode materials, and the steep slope of the straight line in the low‐frequency region corresponds to a small diffusive resistance of the electrolyte in the electrode materials . In the low frequency region, the slopes of sulfide exchanged electrodes (LDH‐S‐15 m and LDH‐S‐12 h) were much steeper than those of the as‐prepared CoAl‐LDH electrode.…”