Starfish-shaped Co₃O₄/ZnFe₂O₄Hollow Nanocomposite: Synthesis, Supercapacity, and Magnetic Properties

Abstract

A novel starfish-shaped porous Co3O4/ZnFe2O4 hollow nanocomposite was fabricated for the first time by a facile and stepwise hydrothermal approach, utilizing metal-organic frameworks as precursors and sacrificial templates. The morphology evolution in the synthetic process upon reaction time and amount of raw materials were investigated in detail. The as-synthesized starfish-shaped porous Co3O4/ZnFe2O4 composites were studied as an electrode material for supercapacitors showing good capacitive performances. Their specific capacitance can reach as high as 326 F g(-1) at 1 A g(-1). The rational combination of components with different potential windows in a composite material enables a wide overall potential range resulting in the highest energy density of 82.5 Wh kg(-1), significantly larger than that of the single components. Magnetic measurements show that the system presents a large coercivity and high squareness (at 1.8 K, Hc = 884 Oe and Mr/Ms = 0.52) with respect to the individual components, which may be attributed to the unique morphology of Co3O4/ZnFe2O4, as well as surface and interface exchange coupling effects. Materials with this novel design and fabrication may show promise for potential applications in electrochemical energy storage and magnetic devices.

Core-double shell ZnO/ZnS@Co3O4 heterostructure as high performance pseudocapacitor

“…5(a). [57][58][59][60][61][62][63][64] The specific capacitance is further enhanced to 777 F g −1 in the case of ZnO/ZnS@Co 3 O 4 which is 10 times higher than that of a commercial Co 3 O 4 -based super- capacitor. Specific capacity values calculated from eqn (1) follow the order ZnO < Co 3 O 4 < ZnO@Co 3 O 4 < ZnO/ZnS@Co 3 O 4 with values of 90 C g −1 , 179 C g −1 , 296 C g −1 and 317 C g −1 respectively.…”

“…ZnS on ZnO augments the charge transfer process in two ways. [57][58][59][60][61][62][63] Long cycle life and the ability to deliver reasonable capacitance at high rates are the two most sought-after attributes of a supercapacitor. 55 Secondly, the band alignment of ZnO@ZnS heterostructures enhances the charge transfer process as described in the schematic shown in Fig.…”

Rational Microstructure Design on Metal–Organic Framework Composites for Better Electrochemical Performances: Design Principle, Synthetic Strategy, and Promotion Mechanism

“…The derived starfish‐shaped Co 3 O 4 /ZnFe 2 O 4 hollow nanocomposites can display 326.7 F g −1 at a current density of 1 A g −1 , which is much higher than that of single Co 3 O 4 (142 F g −1 ) and ZnFe 2 O 4 (112 F g −1 ). The rational combination of components with different potential window into one composite enables a wide overall potential range, resulting in a highest energy density of 82.5 Wh kg −1 …”

“…The rational combination of components with different potential window into one composite enables a wide overall potential range, resulting in a highest energy density of 82.5 Wh kg −1 . [133] Engineering MOFs on the surface of metal oxides nanorod arrays can also be achieved by well-designed procedures. By first engineering Co(OH) 2 seeds on the surface of TiO 2 nanorod arrays on Si substrate through an electrochemical deposition method, the Si/TiO 2 /Co(OH) 2 was then reacted with 2-methylimidazole under 80 °C to convert Co(OH) 2 into Zif-67 crystals due to the slowly dissolving of Co(OH) 2 in 2-methylimidazole containing solutions.…”

An Approach to Preparing Ni–P with Different Phases for Use as Supercapacitor Electrode Materials

“…Hence, considerable amountso fr esearch have been focusedo nt he design of advancede lectrodes with perfect performance for supercapacitors. [8][9][10][11] Pseudocapacitive materials such as hydroxides, [12][13][14][15] oxides, [16][17][18][19][20][21][22][23][24][25][26] sulfides, [27][28][29][30][31] and polymers [32][33][34] are being explored to bring forth supercapacitors with increased specific capacitances and high energy density.H owever,s uch "pseudocapacitors" often resulti nc ompromises in rate capability and reversibility because their electrochemical reactions rely on fast and reversible surface or near-surface redox reactions and these materials have low electricalc onductivity to support the fast electron transport required by high rates. [35] Althought he conductivity of transition metal sulfides is bettert han that of their oxide counterparts, their capacitancep erformance is still limited.…”