Synthesis of NiO–Co₃O₄nanosheet and its temperature-dependent supercapacitive behavior

Abstract

A nanosheet of nickel and cobalt double hydroxides (NC RT) has been synthesized by the facile hydrothermal method. It has been treated at temperatures of 300 °C, 400 °C and 500 °C, namely NC 300, NC 400 and NC 500, respectively, to obtain a nanosheet of NiO-Co 3 O 4 . Samples have been investigated using XRD, Raman spectroscopy, FESEM and TEM. It can be observed that nickel hydroxide is converted to NiO at 300 °C, whereas cobalt hydroxide is converted to Co 3 O 4 at 400 °C. The double hydroxide nanosheet leads to porous oxide nanosheet at an elevated temperature. The formation of porous structure could be attributed to the rapid release of water molecules during thermal treatment. Four symmetric supercapacitors are prepared with NC RT, NC 300, NC 400 and NC 500 as electrode materials, keeping 3 M KOH as an electrolyte and Whatman filter paper as a separator for all the symmetric supercapacitors. It can be seen that the specific capacitances of the NC RT, NC 300, NC 400 and NC 500 symmetric supercapacitors are decreased with increasing temperature in the range of 25 °C-80 °C and scan rate in the range of 10-500 mV s −1 . It can be seen that the NC 300 has excellent supercapacitive behavior. The specific capacitance of NC RT decreased from 20 to 6 F g −1 , NC 300 decreased from 324 to 57 F g −1 , NC 400 decreased from 132 to 61 F g −1 and NC 500 decreased from 81 to 48 F g −1 with the variation of scan rate from 10-500 mV s −1 . The decrement in the specific capacitance may be attributed to the increased bulk and charge transfer resistance at elevated temperature.

Microwave-Assisted Coprecipitation Synthesis and Local Structural Investigation on NiO, β-Ni(OH)2/Co3O4 Nanosheets, and Co3O4 Nanorods Using X-ray Absorption Spectroscopy at Co–Ni K-edge and Synchrotron X-ray Diffraction

“… 9 It can be observed that the Raman broad band between 450 and 519 cm –1 corresponds to the Ni–OH/Co–OH Ni–O/Co–O stretching modes, matching with the literature. 9 , 44 − 47 Hall et al 44 reported on the β-Ni(OH) 2 A 1g mode of the O–H stretching at 1067 cm –1 ; herein it is observed that the broadened peak at 1050 cm –1 in Figure 12 c corresponds to the A 1g mode of the same O–H stretching of β-Ni(OH) 2 of the sample β-Ni(OH) 2 /Co 3 O 4 . 9 , 44 − 46 The peak at 1050 cm –1 is also noted for the 2P mode of Ni–O.…”

“…9,44−46 The peak at 1050 cm −1 is also noted for the 2P mode of Ni−O. 47 Figure 13a reflects the UV−Vis absorption spectra of the synthesized samples in the wavelength range of 200−900 nm. The strongest absorption peak is displayed at 249 and 330 nm for the NiO and β-Ni(OH) 2 /Co 3 O 4 sample, respectively, and three peaks appear at 226, 436, and 748 nm for the Co 3 O 4 sample.…”

Simultaneous Electrodeposition of Ternary Metal Oxide Nanocomposites for High-Efficiency Supercapacitor Applications

“…Cathode-3 exhibited the highest specific capacitance (1800 F g –1 ) compared to cathode-1 (890 F g –1 ), cathode-2 (1200 F g –1 ), and cathode-4 (1400 F g –1 ). Considering the theoretical specific capacitance of the components (3650 F g –1 for Co 3 O 4 , 2584 F g –1 for NiO 2 , and 1370 F g –1 for MnO 2 ), cathode-3 was half pure Co 3 O 4 , which was rather effective as the active material in the pseudocapacitor. , The high specific capacitance of cathode-3 could be attributed to the honeycomb nanosheets (∼10 nm in thickness; see Figure c) providing a higher specific surface area, abundant electroactive sites, and open channels that enhance the contact area between the electrolyte and electrode to improve the diffusion of electrolyte ions into the entire surface of the material . Thus, the effects of Co species should be for both morphological and electrochemical aspects.…”

Synergistically modified WS2@PANI binary nanocomposite-based all-solid-state symmetric supercapacitor with high energy density

“…The specific capacitance, C SP , was calculated from the CV profiles using the expression: 44 , where C SP is specific capacitance, is the area under the CV profile, m is the mass of electrode material (3 mg), V is the scan rate, and Δ V is the potential window taken. Galvanostatic charging–discharging (GCD) measurement of the WS 2 and WS 2 @PANI composites was carried out at a range of current densities (2–8 A g −1 ), and the specific capacitance was calculated by equation: 44 , where I is discharge current measured in A, Δ t is discharge time (s), Δ V is the potential window ( V ), and m is mass. Electrochemical impedance spectroscopic (ESI) studies were performed between 1 Hz and 1 MHz at room temperature.…”