Density functional theory simulation of cobalt oxide aggregation and facile synthesis of a cobalt oxide, gold and multiwalled carbon nanotube based ternary composite for a high performance supercapattery

A novel ternary composite consisting of cobalt oxide (Co3O4) nanoparticles (NPs) grown on multiwalled carbon nanotubes (MWCNTs) and mixed with gold (Au) NPs is synthesized by a single step hydrothermal route. Initially, density functional theory (DFT) simulations were carried out to model the aggregation of Co3O4 NPs and validated further with experimental results. To circumvent this issue, MWCNTs with gold NPs were introduced, which significantly reduced the particle aggregation. Standard three electrode cell studies revealed that the Co3O4/Au@MWCNT composite possesses an excellent energy density, rate capability and very good cyclic stability compared to unsupported Co3O4 or the binary Co3O4@MWCNT. The promising electrochemical performance compared to the single Co3O4 or the binary Co3O4@MWCNT materials is assigned to the synergetic effects of MWCNTs and Au to disaggregate the Co3O4 NPs and to enhance the overall conductivity, respectively. In order to get insight into the evaluation of the performance, two electrode devices were assembled employing activated carbon as a negative electrode and the Co3O4/Au@MWCNT composite as a positive electrode material. The two electrode supercapattery device demonstrated splendid cycling stability with a retention value of 91.90% in 1 M KOH for over 3500 cycles. Additionally, it exhibited an excellent energy density of 18.80 W h kg-1 at a power density of 302.00 W kg-1. These encouraging outcomes can be associated with the distinctive morphology, outstanding conductive networks, increased electroactive sites, and emergence of strong networking of Co3O4, MWCNT and Au in the ternary composite. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique

Recent advances in fiber-shaped and planar-shaped textile solar cells

During the last few years, textile solar cells with planar and fiber-shaped configurations have attracted enormous research interest. These flexible-type solar cells have a huge potential applicability in self-powered and battery-less electronics, which will impact many sectors, and particularly the Internet of Things. Textile solar cells are lightweight, super-flexible, formable, and foldable. Thus, they could be ideal power-harvester alternatives to common flexible solar cells required in smart textiles, electronic textiles, and wearable electronic devices. This review presents a brief overview on fiber-shaped and planar-shaped solar cells, and it introduces the most recent research reports on the different types of textile solar cells, including details on their fabrication techniques. It also addresses the current challenges and limitations of their technology development, and the encountered issues for their future application and integration in novel devices

Recent advances in fiber-shaped and planar-shaped textile solar cells

During the last few years, textile solar cells with planar and fiber-shaped configurations have attracted enormous research interest. These flexible-type solar cells have a huge potential applicability in self-powered and battery-less electronics, which will impact many sectors, and particularly the Internet of Things. Textile solar cells are lightweight, super-flexible, formable, and foldable. Thus, they could be ideal power-harvester alternatives to common flexible solar cells required in smart textiles, electronic textiles, and wearable electronic devices. This review presents a brief overview on fiber-shaped and planar-shaped solar cells, and it introduces the most recent research reports on the different types of textile solar cells, including details on their fabrication techniques. It also addresses the current challenges and limitations of their technology development, and the encountered issues for their future application and integration in novel devices.acceptedVersionPeer reviewe

Development of metal oxide nanostructures incorporated with carbon matrix for electrochemical applications / Numan Arshid

Over the last few decades, nanomaterials have found prodigious potential in various applications of different research fields. Although the metal oxide frame work is not a new class of nanomaterials yet its potential is not explored extensively, especially for electrochemical applications. One of the most significant research motivations for metal oxide frame works come from their tunable morphology, porosity, rigidity/flexibility, variety and facile design which make them capable of using in variety of advanced energy conversion, energy storage and electrochemical sensing devices. However, unsupported metal oxide nanostructures suffers from particle aggregations which lead to decrease their electrochemical surface area. In this work, one step hydrothermal route was used to develop binary nanocomposite of metal oxide (Co3O4) and carbonaceous matrix such as graphene, multiwall carbon nanotubes (MCNTs). The first system, binary composite of reduced graphene intercalated with cobalt oxide (Co3O4) nanocubes was synthesized and the contents of Co3O4 precursor were optimized with respect to fixed amount of reduced graphene oxide (rGO). The rGO−Co3O4 nanocubes was used for supercapacitor application. It was found that with 0.5 mmol of cobalt precursor (A2) gave the highest specific capacity (125 Cg-1) in three electrode cell system. Same nanocomposite was used to fabricate rGO−Co3O4 nanocubes//activated carbon hybrid supercapacitor and the maximum energy and power density was found to be 7.75 Wh.k-1 and 996.42 W.kg-1, respectively. In second system, composite of rGO−Co3O4 nanograins was optimized by varying the contents of rGO with respect to the fixed concentration of Co3O4 precursor. The performance of rGO−Co3O4 nanograins was evaluated for electrochemical sensing of dopamine. The nanocomposite rGO−Co3O4 (B3) with 9.1 wt. % of rGO was optimized on the basis of oxidation current of dopamine. The B3 modified glassy carbon electrode gave 0.277 μL (S/N=3) limit of detection for dopamine in the linear range of 1−30 μL. The performance of B3 modified GCE was also satisfactory in real time urine sample and in the presence of physiological interfering analytes. In the last system, Co3O4 nanocubes were fabricated with MWCNT and the contents of MWCNT with respect to the fixed amount of cobalt precursor were optimized. The MWCNT−Co3O4 nanocube was used for supercapacitor and electrochemical sensing of dopamine application. In both applications, MWCNT−Co3O4 nanocubes (C4) with 16 wt. % of MWCNT demonstrated excellent electrochemical performance compared to its counterparts. The maximum specific capacity was 142 Cg-1 using three electrode cell system. The highest energy density was found to be 19.28 Wh.kg-1 at power density of 309.85 W.kg-1. The optimized nanocomposite (C4) also showed excellent electrochemical performance for dopamine detection. The limit of detection is found to be 0.176 μL in the linear range of 1−30 μL. However, MWCNT−Co3O4 nanocube showed poor selectivity towards dopamine detection. Overall, MWCNT−Co3O4 nanocubes gave better performance for hybrid supercapacitor compared to rGO−Co3O4 nanocubes in terms of specific capacity and energy density. However, rGO−Co3O4 nanograins endowed good sensing capability for dopamine detection in terms of selectivity compared to MWCNT−Co3O4 nanocubes. This work embark the frontiers of carbonaceous materials for electrochemical applications

Electrochemical nano biosensors for the detection of extracellular vesicles exosomes: From the benchtop to everywhere?

Detection of extracellular vesicles (EVs) exosomes is a challenge to address the need for better diagnostic tests and to create a point-of-care (POC) platform that can detect, monitor and treat health conditions early to allow personalized therapies. A multidisciplinary approach is needed to address these health-related technical issues. Over the past decade, materials scientists and engineers have worked on the same platform to develop flexible, lightweight, miniaturized, and integrated POC devices for exosome detection. Therefore, exosome detection based on various nanomaterials is of particular interest. In this paper, we describe the current state of knowledge on 0D-3D nanostructured materials and present a POC-based technique for exosome detection. Finally, the challenges that need to be solved to expand their clinical application are discussed

Poly(Acrylic acid)–Based Hybrid Inorganic–Organic Electrolytes Membrane for Electrical Double Layer Capacitors Application

Nanocomposite polymer electrolyte membranes (NCPEMs) based on poly(acrylic acid)(PAA) and titania (TiO2) are prepared by a solution casting technique. The ionic conductivity of NCPEMs increases with the weight ratio of TiO2.The highest ionic conductivity of (8.36 ± 0.01) × 10−4 S·cm−1 is obtained with addition of 6 wt % of TiO2 at ambient temperature. The complexation between PAA, LiTFSI and TiO2 is discussed in Attenuated total reflectance-Fourier Transform Infrared (ATR-FTIR) studies. Electrical double layer capacitors (EDLCs) are fabricated using the filler-free polymer electrolyte or the most conducting NCPEM and carbon-based electrodes. The electrochemical performances of fabricated EDLCs are studied through cyclic voltammetry (CV) and galvanostatic charge-discharge studies. EDLC comprising NCPEM shows the specific capacitance of 28.56 F·g−1 (or equivalent to 29.54 mF·cm−2) with excellent electrochemical stability

Cobalt nanoparticles as novel nanotherapeutics against Acanthamoeba castellanii

BackgroundSpecies of Acanthamoeba are facultative pathogens which can cause sight threatening Acanthamoeba keratitis and a rare but deadly brain infection, granulomatous amoebic encephalitis. Due to conversion of Acanthamoeba trophozoites to resistant cyst stage, most drugs are found to be ineffective at preventing recurrence of infection. This study was designed to test the antiacanthamoebic effects of different cobalt nanoparticles (CoNPs) against trophozoites and cysts, as well as parasite-mediated host cell cytotoxicity.MethodsThree different varieties of CoNPs were synthesized by utilizing hydrothermal and ultrasonication methods and were thoroughly characterized by X-ray diffraction and field emission scanning electron microscopy. Amoebicidal, encystation, excystation, and host cell cytopathogenicity assays were conducted to study the antiacanthamoebic effects of CoNPs.ResultsThe results of the antimicrobial evaluation revealed that cobalt phosphate Co3(PO4)2 hexagonal microflakes, and 100 nm large cobalt hydroxide (Co(OH)2) nanoflakes showed potent amoebicidal activity at 100 and 10 µg/ml against Acanthamoeba castellanii as compared to granular cobalt oxide (Co3O4) of size 35–40 nm. Furthermore, encystation and excystation assays also showed consistent inhibition at 100 µg/ml. CoNPs also inhibited amoebae-mediated host cell cytotoxicity as determined by lactate dehydrogenase release without causing significant damage to human cells when treated alone.ConclusionsTo our knowledge, these findings determined, for the first time, the effects of composition, size and morphology of CoNPs against A. castellanii. Co3(PO4)2 hexagonal microflakes showed the most promising antiamoebic effects as compared to Co(OH)2 nanoflakes and granular Co3O4. The results reported in the present study hold potential for the development of antiamoebic nanomedicine