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•Temperature tuned synthesis of dual-phase MoS2 namely, 1-T and 2-H.•High specific surface area activated carbon prepared from tendu leaves.•Symmetric and Hybrid activated carbon/MoS2 ...supercapacitors fabricated displays enhanced specific capacitance.•Defective activated carbon/MoS2 composites, for better hydrogen evolution reaction.
Low-cost, earth-abundant, clean and high stability material are of undivided interest for energy storage and conversion. The present work involves the investigation of one such material, activated carbon (AC), that is derived from abundantly available biomass – Tendu leaves. The work also addresses hydrothermal synthesis of 2-D MoS2 layers and composites with AC, for supercapacitors and hydrogen evolution reaction (HER). AC derived from Tendu leaves showed micro and mesopore structure with high specific surface area (SSA) of 1509 m2 g−1. Layered MoS2 nanosheets sheets, showed a biphasic system namely, 1-T and 2-H. Different ratios of AC and MoS2 nanocomposites are prepared. And the best ratio composites tested for symmetric and hybrid supercapacitor electrodes and HER. Symmetric supercapacitor and hybrid supercapacitors exhibited good cycle stability and show higher specific capacitance of 261 F g−1 and 193 F g−1 respectively, at a scan rate of 2 mV s−1. Defective sites were created on AC for electrochemical HER. The defects were created through, hydrothermal N doping followed by high-temperature dedoping of the N-doped AC. The defective activated carbon (DAC) showed a reduction in SSA of 1300 m2 g−1. The nanocomposites of DAC/MoS2 were then tested for HER. The nanocomposites exhibited enhanced catalytic activity owing to better hydrogen evolution with lesser Tafel slope of −84 mVdec−1.
The supercapacitor multilayered electrode materials were prepared potentiodynamically based on polyaniline/activated carbon composite materials. The multilayers comprised of various combinations of ...activated carbon and doped polyaniline layers using three dopants such as sulphuric acid, camphor-10-sulphonic acid and p-toluene sulphonic acid. These composite materials were characterized using SEM, BET Surface area and FTIR. The supercapacitive properties of the fabricated symmetrical supercapacitors were analyzed by cyclic voltammetry, ac impedance and galvanostatic charge–discharge techniques. Based on the electrochemical results best one was chosen for fabricating the symmetrical supercapacitor and it showed the highest specific capacitance of 549.5 F/g. Further, it was found that these multilayered electrode materials gave higher capacitance than their single layered counter parts.
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•Synthesis of four different types of multilayered electrode materials.•Comparison of multilayered electrodes with their single layered counterparts.•The potentiodynamic method used for the electropolymerization of aniline.•Study of the effect of different dopant ions on the charge capacitance.
Lightweight computing technologies such as the Internet of Things and flexible wearable systems have penetrated our everyday lives exponentially in recent years. Without a question, the running of ...such electronic devices is a major energy problem. Generally, these devices need power within the range of microwatts and operate mostly indoors. Thus, it is appropriate to have a self-sustainable power source, such as the photovoltaic (PV) cell, which can harvest indoor light. Among other PV cells, the dye-sensitized solar cell (DSSC) has immense capacity to satisfy the energy demands of most indoor electronics, making it a very attractive power candidates because of its many benefits such as readily available materials, relatively cheap manufacturing methods, roll-to-roll compatibility, easy processing capabilities on flexible substrates and exceptional diffuse/low-light performance. This review discusses the recent developments in DSSC materials for its indoor applications. Ultimately, the perspective on this topic is presented after summing up the current progress of the research.
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► Nanostructure TiO2 has been prepared by a microwave assisted synthesis method. ► Microwave irradiation was varied with time duration on the formation of nanoparticles. ► TiO2-activate carbon show ...very good specific capacitance for supercapacitor. ► Electrochemical properties were studied on electroanalytical techniques.
Electrochemical properties of a supercapacitor based on nanocomposite electrodes of activated carbon with TiO2 nano particles synthesized by a microwave method have been determined. The TiO2/activated carbon nanocomposite electrode with a composition of 1:3 showed a specific capacitance 92Fg−1. The specific capacitance of the electrode decreased with increase in titanium dioxide content. The p/p symmetrical supercapacitor fabricated with TiO2/activated carbon composite electrodes showed a specific capacitance of 122Fg−1. The electrochemical behavior of the neat TiO2 nanoparticles has also been studied for comparison purpose. The galvanostatic charge–discharge test of the fabricated supercapacitor showed that the device has good coulombic efficiency and cycle life. The specific capacitance of the supercapacitor was stable up to 5000 cycles at current densities of 2, 4, 6 and 7mAcm−2.
The work presented in this paper demonstrates an experimental path to improve the performance of a screen-printed flexible thermoelectric generator through optimization of leg materials, geometrical ...and structural parameters of the leg, and the viscosity of screen-printed ink. A thin and porous screen-printed leg structure improves the Seebeck coefficient and power output by 11.53 and 8.52 times, respectively than a thick and denser leg structure. A trapezoidal design increases the Seebeck coefficient, and power output by 2.72 and 3.82 times, respectively, compared with a rectangular leg structure. The observed increment in the power output using silver as contact material is about 2.17 times higher than graphene. Screen ink with higher ink viscosity results in a 47 % reduction of transient thermal conductivity and an increased power factor by 20.33 times. The rectangular leg produces the maximum power factor of 1.30 × 10−12 µWmm−2K−2. The improvement possible in the power output by controlling the leg structure's porosity is around 752.71 %. The result indicates that optimization of ink viscosity and porosity of ink film has significant influence in enhancing the performance of FTEG than its leg shapes and material properties.
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•Performance optimization of PANI/Graphite based screen printed FTEG is developed.•Trapezoidal leg shape is preferable over rectangular to enhance the power output.•Influence of ink viscosity is prominent than leg geometry on FTEG performance.•The higher electrical resistance of contact material enhances the voltage output.•Porous ink film reduced thermal conductivity and enhanced power output.
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Today Perovskite solar cell (PSC) has achieved efficiency close to 26%, surpassing the efficiencies of well- known Dye-Sensitized Solar cells (DSSC), CdTe-based solar cells, etc. Ease ...of preparing perovskite solutions and convenient deposition technique has given them added advantage over other contemporary competitors. This has also made them an economically feasible option. Since the inception of PSCs in 2009, a lot of improvements have been done in various aspects like composition, synthesis technique, fabrication method, and interface study. However, today it is crucial to think about the commercialization of PSCs. In this direction, the stability of PSCs has been a long-standing question. This review focuses on the key aspects of perovskite stability. Challenges posed by environmental factors like moisture, oxygen, temperature, and light are still unanswered. The lead toxicity of PSCs demands a potential substitute of lead with no compromise in their efficiency. The lead-free approach of PSCs and their commercialization has been discussed separately. A suitable emphasis has been given to the encapsulation of solar cells, as we find it a necessary part of the future commercialization process. This review has been addressed with an ideology to provide overall knowledge on the stability issues and challenges concerned with the PSCs, to attract young research community towards this emerging field.
The dearth of information about the fabrication of flexible polyaniline and graphite-based microporous and low-cost thermoelectric generators using screen printing for low-temperature applications ...has motivated us to undertake this research work. Polyaniline and graphite composite inks were formulated using cellulose acetate as resin and diacetone alcohol as the solvent. In this work, we have studied the influence of ink ingredients on the thermoelectric properties of composite inks. Diacetone alcohol improved the electrical conductivity of polyaniline by 7.9 times. The carrier concentrations and carrier mobility of composite ink were enhanced by 2.8 times. Simultaneously, cellulose acetate increased resistivity and carrier mobility of polyaniline by 13 and 44 times, respectively. Graphite improved the crystallinity but reduced carrier mobility, carrier concentration, and bandgap of the composite inks. Screen-printed porous ink film structure reduced the thermal conductivity of PANI ink by 11 times at 333 K. The maximum Seebeck coefficient and power output exhibited by the fabricated thermoelectric generator were 244.34 μV/K and 4.31 nW, respectively at 77 K. Present work explored fabrication and characterization of low cost, flexible polyaniline and graphite composite ink-based thermoelectric generator with improved Seebeck coefficient and power output for low-level heat energy conversion.
•Polyaniline/graphite ink-based flexible thermoelectric generator is screen printed.•Cellulose acetate resin improved resistivity and carrier mobility of polyaniline.•Diacetone alcohol solvent enhanced electrical conductivity of polyaniline.•Graphite in polyaniline reduced carrier concentration, mobility, and bandgap.•The porous leg thermoelectric generator produced a power output of 4.31 nW at 77 K.
Human skin emits a series of volatile compounds from the skin due to various metabolic processes, microbial activity, and several external factors. Changes in the concentration of skin volatile ...metabolites indicate many diseases, including diabetes, cancer, and infectious diseases. Researchers focused on skin-emitted compounds to gain insight into the pathophysiology of various diseases. In the case of skin volatolomics research, it is noteworthy that sample preparation, sampling protocol, analytical techniques, and comprehensive validation are important for the successful integration of skin metabolic profiles into regular clinical settings. Solid-phase microextraction techniques and polymer-based active sorbent traps were developed to capture the skin-emitted volatile compounds. The primary advantage of these sample preparation techniques is the ability to efficiently and targetedly capture skin metabolites, thus improving the detection of the biomarkers associated with various diseases. In further research, polydimethyl-based patches were utilized for skin research due to their biocompatibility and thermal stability properties. The microextraction sampling tools coupled with high sensitive Gas Chromatography-Mass Spectrometer provided a potential platform for skin volatolomes, thus emerging as a state-of-the-art analytical technique. Later, technological advancements, including the design of wearable sensors, have enriched skin-based research as it can integrate the information from skin-emitted volatile profiles into a portable platform. However, individual-specific hydration, temperature, and skin conditions can influence variations in skin volatile concentration. Considering the subject-specific skin depth, sampling time standardization, and suitable techniques may improve the skin sampling techniques for the potential discovery of various skin-based marker compounds associated with diseases. Here, we have summarised the current research progress, limitations, and technological advances in skin-based sample preparation techniques for disease diagnosis, monitoring, and personalized healthcare applications.
Analytical technique for monitoring skin-emitted metabolites to diagnose diseases.
Biodegradable polymer electrolyte comprising the blend of chitosan (CS) and starch, plasticized with glycerol, as host polymer and lithium perchlorate (LiClO4) as a dopant is prepared by solution ...casting technique. The variation of conductivity has been investigated as a function of polymer blend ratio, plasticizer content, and LiClO4 concentration at temperature range of 298–343K using electrochemical impedance spectroscopy. The maximum conductivity is found to be 3.7×10−4Scm−1 at room temperature for 60:40 (CS/starch) concentration. The dielectric properties of the electrolyte film exhibit a long tail feature indicating good capacitance. The activation energy of all samples is evaluated using the Arrhenius plot and it is found to be 0.52–0.75eV. The DSC thermogram peaks for CS-starch blends decreases with increase in the LiClO4 content. A carbon–carbon supercapacitor is fabricated using suitable blend electrolyte ratio and its electrochemical characteristics are discussed at various temperatures and current density. This supercapacitor shows a fairly good specific capacitance of 133Fg−1.
Nanostructures of noble metals were immensely studied owing to their eminent salient features like morphology, controllable size dispersity and surface chemistry. Herein, we report a facile and ...eco-friendly route to synthesize gold nanoparticles (CGAuNPs) within a shorter period of time using the aqueous fruit extract of Couroupita guianensis Aubl. (CGFE) as a potential bioreductant to reduce Au3+ ions into their nanoscale counterparts. Growth of CGAuNPs generates a shift in the color of reaction medium due to the excitation of surface plasmon resonance (SPR) which produces an intense absorbance peak at 530nm in UV–Visible spectroscopy. Fourier transform infrared spectroscopy (FTIR) confirms the active role of water soluble phenolic compounds in achieving the reduction and stabilization of CGAuNPs. Additionally, transmission electron microscope (TEM) and X-ray diffraction (XRD) studies revealed that the synthesized CGAuNPs were anisotropic face centered cubic crystalline in nature, having an average size of 26±11nm. Dynamic light scattering (DLS) and Energy dispersive spectroscopic (EDAX) results were proved that the synthesized CGAuNPs were free from contaminants and they were stable, possessing negative electric charge without aggregation. On the other hand, in vitro antioxidant assays demonstrate that the aqueous CGFE and formulated CGAuNPs possess extraordinary antioxidant properties. Hemocompatibility assay depicts the safe nature of synthesized CGAuNPs for biomedical applications. Thus, the results of present study will be useful to synthesize AuNPs instantly via green chemistry route for its valuable applications in nanomedicine.
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•Instant green synthesis of anisotropic gold nanoparticles using fruit extract of C. guianensis•Physio-chemical characterization and identifying the role of phenolic antioxidants on functionalization of NPs•In vitro antioxidant and biocompatibility assessment of synthesized NPs
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