Design and synthesis of ternary Co₃O₄/carbon coated TiO₂ hybrid nanocomposites for asymmetric supercapacitors

Abstract

Recently, attention has been focused on the synthesis and application of nanocomposites for supercapacitors, which can have superior electrochemical performance than single structured materials. Here, we report a carbon-coated TiO2/Co3O4 ternary hybrid nanocomposite (TiO2@C/Co) electrode for supercapacitors. A carbon layer was directly introduced onto the TiO2 surface via thermal vapor deposition. The carbon layer provides anchoring sites for the deposition of Co3O4, which was introduced onto the carbon-coated TiO2 surface by hydrazine and the thermal oxidation method. The TiO2@C/Co electrode exhibits much higher charge storage capacity relative to pristine TiO2, carbon-coated TiO2, and pristine Co3O4, showing a specific capacitance of 392.4 F g(-1) at a scan rate of 5 mV s(-1) with 76.2% rate performance from 5 to 500 mV s(-1) in 1 M KOH aqueous solution electrolyte. This outstanding electrochemical performance can be attributed to the high conductivity and high pseudo-capacitive contributions of the nanoscale particles. To evaluate the capacitive performance of a supercapacitor device employing the TiO2@C/Co electrode, we have successfully assembled TiO2@C/Co//activated carbon (AC) asymmetric supercapacitors. The optimized TiO2@C/Co//AC supercapacitor could be cycled reversibly in the voltage range from 0 to 1.5 V, and it exhibits a specific capacitance of 59.35 F g(-1) at a scan rate of 5 mV s(-1) with a specific capacitance loss of 15.4% after 5000 charge-discharge cycles. These encouraging results show great potential in terms of developing high-capacitive energy storage devices for practical applications.

Three-Dimensional Co3 O4 @NiCo2 S4 Core/Shell Nanoflower Array with Enhanced Electrochemical Performance

“…With respect to S 2p spectrum, the peak at about 163.1 eV (S 2p1/2) is assigned to the binding energy of metal-sulfur bond (including NiÀS or CoÀS bond), while the component at 161.8 eV (2p 3/2) is the feature of the sulfur ions in low coordination at the surface. Aforementioned results accord with the previous reported data of NiCo 2 S 4 , [29,30] indicating that the surface ingredient of the hybrid product is composed of Co 3 + /Co 2 + , Ni 3 + /Ni 2 + , S 2À and proving the existance of NiCo 2 S 4 .…”

“…[23] Therefore, lots of supercapacitive materials are based on various morphology of Co 3 O 4 . [24][25][26][27][28][29][30][31][32][33] For example, Zheng et al have synthesized mesoporous Co 3 O 4 nanowires as efficient water oxidation electrocatalysts and supercapacitor electrodes. [31] Cheng et al has reported Co 3 O 4 @MnO 2 hierarchical nanoneedle arrays applied to energy storage.…”

High-rate-capability asymmetric supercapacitor device based on lily-like Co3O4nanostructures assembled using nanowires

“…Compared with those in previous studies (Table 1), the specic capacitance and cycling performance at high current density is notably improved. [48][49][50][51][52][55][56][57] The asymmetric supercapacitor device was further assembled with the as-prepared Co 3 O 4 /Ni and active carbon (Co 3 O 4 / Ni//AC). The electrochemical performance was evaluated and the results are shown in Fig.…”

“…For example, one-dimensional Co 3 O 4 nanostructures showed preferable electrochemical properties in previous studies. [48][49][50][51][52] To date, large attention has been drawn towards using different methods for the synthesis of one dimensional Co 3 O 4 nanostructures with excellent electrochemical properties (e.g. hydro-thermal method).…”

Hierarchical Co3O4@Co9S8 nanowall structures assembled by many nanosheets for high performance asymmetric supercapacitors

“…However, in practice application, single Co 3 O 4 materials possess poor electrode stability and low cyclic stability. 23,24 Therefore, one has designed various hybrid structures to use their synergetic effect to improve the electrochemical properties of Co 3 O 4 nanomaterials. Du et al successfully synthesized porous Co 3 O 4 nanosheets@RGo nanocomposite using a simple hydrothermal process.…”