In this research work, SnO₂, NiO and SnO₂/NiO nanocomposites were synthesized at low temperature by modified sol–gel method using ultrasonication. Prepared samples were investigated for their properties employing various characterization techniques. X-ray diffraction (XRD) patterns confirmed the purity and phase of the samples as no secondary phase was detected. The average crystallite size of the nanocomposites was found to decrease from 19.24 to 4.53 nm with the increase in NiO concentration. It was confirmed from SEM micrographs that the material has mesoporous morphology. This mesoporous morphology resulted in the increase of the surface to mass ratio of the material, which in turn increases the specific capacitance of the material. The UV–Visible spectra showed the variation in the band gap of SnO₂/NiO at different weight ratio ranging from 3.49 to 3.25 eV on increasing NiO concentration in the samples. These composites with different mass ratio of SnO₂ and NiO were also characterized by FT-IR spectroscopy that showed shifting of the peaks centered at 545 cm⁻¹ in the spectra for NiO/SnO₂ nanocomposite. The analysis of the electrochemical performance of the material was done with the help of cyclic voltammetry and Galvanostatic charge–discharge. The specific capacitance of the synthesized samples with different concentration of SnO₂ and NiO was analyzed at different scan rates of 5 to 100 mV/s. Interestingly, 7:1 mass ratio of NiO and SnO₂ (SN7) nanocomposite exhibited a maximum specific capacitance of ~ 464 F/g at a scan rate of 5 mV/s and good capacitance retention of 87.24% after 1,000 cycles. These excellent electrochemical properties suggest that the SnO₂/NiO nanocomposite can be used for high energy density supercapacitor electrode material.

Interest in pseudocapacitive materials, especially cuprous oxide, has grown owing to its various advantageous properties and application as electrode materials in the energy storage devices. The work presented here, a cubic Cu₂O framework was synthesized using a simple and one-step modified polyol-assisted (metal-organic framework) solvothermal method. The structural configuration was rationalized by systematically studying the effect of the reaction time on the morphology and growth of the Cu₂O. In addition, a range of microscopic and spectroscopic techniques was employed to further characterize the obtained cubic Cu₂O. The morphological effect on the electrochemical supercapacitive performance of the obtained cubic Cu₂O was also examined by cyclic-voltammetry (CV) and galvanostatic-charge-discharge (G-C-D) method. The obtained outcome shows that the cubic Cu₂O synthesized using a reaction time of 12 h (Cu₂O-12h; C_sp~365 Fg⁻¹) exhibited superior capacitive performance as compared to the cubic Cu₂O synthesized at 8 h (Cu₂O-8h; C_sp~151 Fg⁻¹) and 10 h (Cu₂O-10h; C_sp~195 Fg⁻¹) at the current density of 0.75 Ag⁻¹. Furthermore, the Cu₂O-12h electrode exhibits energy density of 16.95 Wh/Kg at a power density of 235.4 W/Kg and higher power density of 2678.5 W/Kg at low current density. In particular, the cube-like Cu₂O-12h exhibited excellent capacitive performance and rate capability as compared to Cu₂O-8h and Cu₂O-10h, owing to its unique three-dimensional morphology, which facilitates the formation of various active sites for intercalation of the electrolyte during the electrochemical process. These results show the as-obtained Cu₂O could be a promising supercapacaitive electrode material for various applications.

Organic–inorganic functional hybrid polymeric materials are well known for the efficient removal of contaminants from wastewater. Herein, mechanical exfoliation of bulk MoS₂ and its composite with polyaniline (Pani@MoS₂) via facile in situ oxidative polymerization has been reported. The application of the Pani@MoS₂ hybrid adsorbent to the scavenging of the organic pollutant dye Congo red (CR) from an aquatic environment in batch experiments has been investigated. The adsorption and removal of CR using Pani/MoS₂ was much higher than the bulk and exfoliated MoS₂ nanosheets. The effects of varying experimental conditions, such as pH, temperature, CR concentration, and interaction time between the adsorbent and CR at which optimal removal occurs, were examined. The highest adsorption of 70.921 mg g⁻¹ was recorded at 120 min, pH 5, and 50 °C and was due to the π–π and electrostatic interactions between the nitrogen containing groups of the adsorbent and CR molecules. The adsorption equilibrium data were well fitted to the Langmuir adsorption isotherm model, revealing monolayer coverage of the CR molecules on the Pani@MoS₂ nanohybrid adsorbent. The CR adsorption kinetics and thermodynamics were also studied to gain a better understanding of the adsorption mechanism and the interaction between the CR molecules and the active sites present on the Pani@MoS₂ nanohybrid. The results show that Pani/MoS₂ is an efficient adsorbent for the removal of CR dye from wastewater.

Porous carbons are highly attractive and demanding materials which could be prepared using biomass waste; thus, they are promising for enhanced electrochemical capacitive performance in capacitors and cycling efficiency in Li-ion batteries. Herein, biomass (rice husk)-derived activated carbon was synthesized via a facile chemical route and used as anode materials for Li-ion batteries. Various characterization techniques were used to study the structural and morphological properties of the prepared activated carbon. The prepared activated carbon possessed a carbon structure with a certain degree of amorphousness. The morphology of the activated carbon was of spherical shape with a particle size of ~40–90 nm. Raman studies revealed the characteristic peaks of carbon present in the prepared activated carbon. The electrochemical studies evaluated for the fabricated coin cell with the activated carbon anode showed that the cell delivered a discharge capacity of ~321 mAhg⁻¹ at a current density of 100 mAg⁻¹ for the first cycle, and maintained a capacity of ~253 mAhg⁻¹ for 400 cycles. The capacity retention was found to be higher (~81%) with 92.3% coulombic efficiency even after 400 cycles, which showed excellent cyclic reversibility and stability compared to commercial activated carbon. These results allow the waste biomass-derived anode to overcome the problem of cyclic stability and capacity performance. This study provides an insight for the fabrication of anodes from the rice husk which can be redirected into creating valuable renewable energy storage devices in the future, and the product could be a socially and ethically acceptable product.

This paper investigates the mechanism of light-soaking effects in inverted organic photovoltaic devices with zinc oxide and aluminum doped ZnO electron transport layers, which is important for development of low-cost and stable solar cells.