Cobalt oxide (Co3O4)/graphene nanosheets (GNS) composite prepared by novel route for supercapacitor application

Abstract

Cobalt oxide (Co 3 O 4 )-graphene nanosheets (GNS) composite was prepared using a novel route. Room temperature prepared graphite oxide was exfoliated at low temperature and subsequently reduced to GNS by chemical method. Successful compound formation was confirmed and structural details were obtained from XRD studies. Cobalt oxide was found to crystallize in spinel fcc structure with average crystallite size of 9 nm in the composite. FTIR and XPS study confirms the removal of oxygen containing functional group in reduced graphene and spinel formation of cobalt oxide in the composite. Raman spectra depict the reestablishment of sp 2 conjugated network of carbon atoms, on reduction to graphene. FESEM images reveal the nanosheet like morphology of the graphene being retained in the composite and promoting ion diffusion channels. Electrochemical characterization discloses the pseudocapacitive behaviour of the composite material. Higher specific capacitance of 650 F/g was exhibited by GNS-Co 3 O 4 at 5 mV/s scan rate. Symmetrical supercapacitor fabricated using GNS-Co 3 O 4 demonstrated superior power characteristics. Graphene in the composite has substantially increased the electron and ion transport in the electrode material leading to enhanced performance.

3D Graphene Frameworks/Co3O4 Composites Electrode for High‐Performance Supercapacitor and Enzymeless Glucose Detection

“…The high resolution O 1s spectrum (Figure f) can be fitted into three peaks at 526.8, 529.4, and 530.9 eV. The main peak centered at 529.4 eV is attributed to metal–oxygen bonds for the Co 3 O 4 phase, with a shoulder at 530.9 eV belonging to oxygen ions in low coordination states at the surface, which is in agreement with the reported literature . The peak appearing at 526.8 eV corresponds to hydroxyl CO groups on the edge of cyclobenzene .…”

Effect of rGO Coating on Interconnected Co3O4 Nanosheets and Improved Supercapacitive Behavior of Co3O4/rGO/NF Architecture

“…As a distinct comparison, the Co 3 O 4 /NF electrode exhibits specific capacitances of 520.0, 513.7, 485.8, 456.8, 444.5, and 435.5 F g −1 at the corresponding current densities. Moreover, compared to other previously reported Co 3 O 4 /rGO composites with different Co 3 O 4 microstructures [ 7 , 16 , 30 ], the Co 3 O 4 /rGO/NF electrode reported here also delivers superior specific capacitances especially at higher current densities. Here, it is worth noting that the specific capacitance decreases as the charge/discharge current density increases for both Co 3 O 4 /rGO/NF and Co 3 O 4 /NF.…”

“…Geng et al [ 6 ] prepared porous Co 3 O 4 nanoplates with a specific capacitance of ~231 F g −1 at a current density of 1 A g −1 using a facile reflux method. Naveen et al [ 7 ] synthesized Co 3 O 4 /graphene nanosheets by a chemical method and a high specific capacitance of ~650 F g −1 at a scan rate of 5 mV s −1 . However, there still remain some challenges in the practical applications of Co 3 O 4 as a high capacity electrode such as poor conductivity and cycling stability, and relatively lower experimental specific capacitances than the theoretical value.…”

Nanostructured (Co, Mn)3O4 for High Capacitive Supercapacitor Applications

“…The charge curve was consisting of two segments. A linear variation with time (0.01–0.33 V) parallel to the vertical axis shows the typical characteristic of electric double layer capacitance and a sloped variation with time (0.33–0.55 V) is due to the redox process [36–38] of (Co, Mn) 3 O 4 . It can be identified from the charge/discharge profiles that the major type of charge storage behaviors in as synthesized electrode materials were based on Faraday reactions which were in good consistence with the CV studies.…”