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With externally hydro-responsive PVA particle dispersion and their excluded volume, the CZTO/SWCNT/PDMS hybrid composite structure offers exceptionally high smart green electromagnetic shielding.

In this study, we present an innovative approach for the fabrication of efficient electromagnetic shielding material by tuning the microstructure of the filler in a flexible PDMS polymer matrix.

Here, we have fabricated a high performance asymmetric supercapacitor (ASC) device consisting of honeycomb-like nickel–copper–carbonate–hydroxide (NC) coated stainless steel (SS) as a positive and ...

Herein, a distinctive approach has been implemented for exploiting a typical battery material zinc vanadium oxide (ZV) as a supercapacitor electrode material. Aiming to achieve fascinating capacitive properties, a hybrid (ZnV2O6@PPy) of the conducting polymer polypyrrole (PPy)-decorated ZV was synthesized via a hydrothermal protocol, followed by low-temperature in situ oxidative polymerization. The hybrid electrode ZnV2O6@PPy (ZVP) benefited from its interconnecting network architecture, mesoporous feature, conductive feature, and rich redox chemistry, which contributed to the charge storage performance to ensure a remarkable specific capacitance (Cs) of 723.6 F g−1 at 1 A g−1 current density that outweighed the Cs of ZV at 402 F g−1. Moreover, an asymmetric supercapacitor (ASC) device (based on ZnV2O6@PPy as the positive electrode and the nitrogen-doped reduced graphene oxide (NG) as the negative electrode) delivered a maximum Cs of 109.2 F g−1 at 1 A g−1 within an impressive voltage window of 0–1.5 V. The ASC provided a maximum energy density of 34 W h kg−1 at a power density of 748.7 W kg−1, maintaining a reliable cycle life of 93% over 3000 galvanostatic charge–discharge cycles. Two serially associated ASC devices can power up the red LED indicator for quite a long time. The comprehensive experimental output of the ASC supports the promising application of the device as a supercapacitor electrode application.

Prodigious worldwide executions of portable/wearable multifunctional electronic gadgets have motivated the researchers to innovate miscellaneous flexible and maintenance-free self-charging power packs by the judicious assimilations of diverse energy harvesters with suitable electrochemical energy storage systems. However, it is definitely challenging to assimilate an energy-harvesting system (piezoelectric/triboelectric nanogenerators and solar cells) with an electrochemical energy storage cell (supercapacitors and batteries) within a solitary power package with greater ambient energy conversion/storage efficiency. Over the past decades, substantial research efforts have been devoted to instigating proficient piezoelectric/triboelectric nanogenerator and photovoltaic cell-driven supercapacitors and battery-based diverse self-charging power packs in order to mitigate the drawbacks of the conventional energy storage systems (e.g., restricted time-spans for discharging and moderate-to-low intrinsic capacities). Besides, repetitive charging and frequent replacements of such energy storage cells are other obstacles for their real-time operations. In this chapter, we will focus on the recent developments of piezoelectric/triboelectric/photovoltaics-driving self-charging supercapacitor/battery-based power systems, rectification-free piezoseparator-driving systems, individual self-charging mechanisms, key approaches to augment their efficiencies/self-charging abilities, and future scopes, succinctly.

Expeditious commercialization of manifold personalized electronic appliances has encouraged modern researchers to innovate maintenance-free high-performance energy-harvesting/conversion systems such as piezoelectric/triboelectric/hybrid nanogenerators (PENGs/TENGs/HNGs) and energy storage systems viz. supercapacitors/batteries. An effective strategy to harvest accessible ambient energies and their successive storages will be challenging to alleviate the energy necessities. Over decades, some state-of-the-art energy-harvesting/conversion technologies have been developed by contriving PENGs/TENGs/HNGs. Likewise, various advanced energy storage/conversation systems have been developed using capacitive/battery-type electrodes with decent electrochemical features. Typically, barium titanate, strontium titanate, zinc oxide, zinc stannate, lead zirconate titanate (all-inorganic-based) and poly l -lactic acid, polyvinylidene fluoride, silk, collagen, cellulose (organic-based piezoelectric materials) are employed in PENGs. Besides, TENGs typically involve two different triboelectric friction surfaces with different polarities. For energy storage, both the supercapacitors and/or batteries have been utilized expansively. In this chapter, we highlight concisely on recent developments of several functional materials/devices exploited for ambient mechanical energy-harvesting/conversions and storage applications. Besides, the primary approaches to augment their efficiencies and future scopes are highlighted concisely.

The present study describes the electromagnetic interference shielding effectiveness (EMI SE) of poly (vinyl chloride) (PVC)/MWCNT nanocomposites prepared by solution blending in the presence of PVC beads and their corresponding electrically conductivity. Commercial PVC beads were added to the high viscous media of solution blended PVC-MWCNT during solvent evaporation of the prepared PVC/MWCNT nanocomposite. Addition of PVC beads increased the EMI SE and electrical conductivity values of the nanocomposite compared to the PVC/MWCNT nanocomposite without any PVC beads. Additionally, both EMI SE and electrical conductivity were also increased with increasing content of PVC bead at constant MWCNT loading in the nanocomposite. The insulating PVC bead regions are free from any MWCNT and acts as dispersed domains (excluded volume) which enhances effective concentration of MWCNT in the continuous PVC phase of the nanocomposites, and thus, play the key role to lower the percolation threshold, enhance the EMI SE and electrical conductivity values of the nanocomposite. The nonconductive PVC bead region in the nanocomposite acts as excluded volume that attenuates the microwave energy through multiple internal reflections by creating an impedance mismatch in the nanocomposites.

An advanced novel all-solid-state asymmetric supercapacitor (ASC) device of high energy and power densities is designed on the basis of the nanoflower-like NiSe as the positive electrode and WO3@PPy composite as the negative one. The porous NiSe was prepared by facile selenization of predesigned NiO nanoflowers, and the WO3@PPy composite was synthesized through in situ oxidative polymerization of pyrrole in the presence of dispersed WO3 nanosticks which, in turn, was produced by a simple sulfate-assisted hydrothermal method. When tested as a supercapacitor positive electrode in the three-electrode system, the NiSe exhibits an appreciably higher specific capacitance of 1274 F g–1 at 2 A g–1 than that of the NiO nanoflower (774 F g–1). Again, as the negative electrode, the WO3@PPy composite also shows excellent electrochemical properties with a higher specific capacitance (586 F g–1 at 2 A g–1) than those of either of its components (WO3: 402 F g–1 and PPy: 224 F g–1). Based on these properties of the respe...

Development of flexible, durable and biocompatible piezoelectric/acoustic/wind multi-functional energy harvester with remarkable energy conversion efficiency, high current, and power density is of great challenge in scavenging electricity from multi-modes of energy sources for powering real smart electronics and e-healthcare monitoring devices. Here, bio-inspired vitamin B2 (VB2) assisted PVDF based multifunctional advanced energy material with high out-of-plane piezoelectric co-efficient of ~ –50.3 pC/N, is reported first time for harvesting huge electrical energy from multi-modes of alternative energy sources in a single device. Thus, an entirely organic based fully biocompatible piezoelectric nanogenerator (PNG) having multifunctional energy harvesting capabilities at a time (mechanical/acoustic/wind) has been designed by integrating VB2 with PVDF. VB2 is introduced in energy-harvesting family for first time as an effective β-phase (~93%) stabilizer for PVDF and would be better replacement of non-toxic expensive stabilizers. The fabricated nanogenerator reveals high output current (≈12.2 μA) and voltage (≈61.5 V), theoretically verified with finite element method (FEM) based simulation. The device with fast-charging capability shows remarkable peak power density of ≈9.3 mW/cm3 and ultrahigh energy conversion efficiency (≈62%) enabling lightening more than 100 LEDs directly and can power up a CD motor/mobile through capacitor charging. Moreover, generation of electricity from various noises allows potentiality of the device as an artificial acoustic ultra-sensor. Thus, it would provide more opportunities towards next generation multifunctional emerging power sources and in e-healthcare monitoring.

We demonstrate a cost-effective synthesis of 3D quaternary copper–nickel–cerium–cobalt oxide (Cu–Ni–Ce–Co oxide) through a one-step hydrothermal protocol followed by a heat treatment process. The m...

The expeditious growth of portable electronics has endorsed the researchers to develop self-powered devices that synchronically harvest and store energy. However, it is quite challenging to integrate two distinct phenomena in a single portable device. Here, we emphasize the fabrication of a triboelectric driven self-charging and self-healing asymmetric supercapacitor (SCSHASC) power cell composed of magnetic cobalt ferrite grown on a stainless steel (SS) fabric (CoFe

Triboelectric nanogenerators (TENGs) represent a comprehensive achievement in green and eco-friendly technology by transforming ambient mechanical energy into electrical energy. Enhancement of the tribo-charge density on the active layer of TENGs has become a fundamental method of augmenting the output performance of TENGs in realistic environments to increase their use in daily applications. Herein, an approach of coupling piezoelectric/ferroelectric properties, internal resistance, and surface texture of the composite film is established to optimize the output performance of poly-dimethylsiloxane (PDMS)/zinc stannate (ZnSnO3)/multi-walled carbon nanotube (MWCNT) composite based TENGs. The effect of piezoelectricity, internal resistance, and surface treatment on output is explained experimentally and theoretically, which illustrates that the extent of charge transfer has a strong connection with the piezoelectricity, internal resistance, and surface treatment of the composite. With optimization of these controlling factors, under human finger tapping the fabricated TENG exhibited an open circuit voltage of ∼475 V, a short-circuit current of ∼36 μA, and a charge density of ∼0.062 mC cm−2, which gives a maximum power of ∼4.2 mW at ∼50 MΩ resistance. Moreover, the designed TENG is able to harvest electrical energy efficiently from various human movements with an energy conversion efficiency of ∼68%, and the output power of the TENG can be used directly or after storage in a capacitor. Thus, this work will deliver not only a new, effective and feasible approach to improve the generated output power from nanogenerators, but also deliver a new opening for constructing high performance TENGs for self-powered day-to-day use electronics.

Living tissue uses stress-accumulated electrical charge to close wounds, yet to-date this piezoelectric effect has not been realised in self-repairing synthetic materials which are typically soft amorphous materials requiring external stimuli, prolonged physical contact and long healing times (often >24h). Here we overcome many of these challenges using piezoelectric organic crystals, which upon mechanical fracture, instantly recombine without any external direction, autonomously self-healing in milliseconds with remarkable crystallographic precision. Atomic-resolution structural studies reveal that a 3D hydrogen bonding network, with ability to store stress, facilitates generation of stress-induced electrical charges on the fractured crystals, creating an electrostatically-driven precise recombination of the pieces via a diffusionless instant self-healing, as supported by spatially-resolved birefringence experiments. Perfect, instant self-healing creates new opportunities for deployment of molecular crystals in robust miniaturised devices, and may also spur development of new molecular level repair mechanisms in complex biomaterials.

Autonomous self-healing The ability to autonomously restore shape or self-heal are useful properties that have been incorporated into a range of materials, including metals and polymers. Bhunia et al. found that both of these abilities could be achieved in piezoelectric molecular crystals, specifically bipyrazole organic crystals. When the crystals are fractured, they develop charged surfaces that attract each other, drawing the two faces together to enable self-repair as long as they remain within a critical distance of each other. The effect can also be seen in other noncentrosymmetric piezoelectric crystals. Science , abg3886, this issue p. 321

With the advancement of the modern ultrasmart world, our surroundings have become a dumping ground for electronic wastes, which not only is a threat to human lives, but has become dangerous for any living creature as well as for ecosystems. To keep our ecosystems healthy, the need has arisen to take immediate action against electronic waste. To overcome these issues, the design of smart devices with nontoxic, biodegradable or biocompatible materials is urgently desired, which will lead to devices that are easily recyclable, processable, and safe for the environment/living creatures. In recent times, piezoelectric/triboelectric nanogenerators (PNGs/TNGs) have attracted more and more attention among other renewable green energy-harvesting sources because of their easy accessibility, abundant sources, and conversion of mechanical energy into green electricity. Due to the toxic nature and incompatibility of inorganic/some organic-based PNGs/TNGs the designing of effective nature-driven bionanogenerator (PNG/TNG) devices with biocompatible/biodegradable materials would be a smart approach toward a future green electronics world. Here, we discuss the effectiveness of biowaste biodegradable materials in green energy harvesting technologies and their possible applications in a future smart/portable electronics world. Furthermore, using biowaste materials in energy-harvesting technology will help to clean biowastes from the environment as well as society.

The unique combination of piezoelectric energy harvesters and light detectors progressively strengthens their application in the development of modern electronics. Here, for the first time, we fabricated a polyvinylidene fluoride (PVDF) and formamidinium lead bromide nanoparticle (FAPbBr3 NP)-based composite aerogel film (FAPbBr3/PVDF) for harvesting electrical energy and photodetector applications. The uniform distribution of FAPbBr3 NPs in FAPbBr3/PVDF was achieved via the in situ synthesis of FAPbBr3 NPs in the PVDF matrix, which led to the stabilization of the γ-phase. The freeze-drying process induced an interconnected porous architecture in the composite film, making it more sensitive to small mechanical stimuli. Owing to this unique fabrication technique, the constructed aerogel film-based nanogenerator (FPNG) exhibited an output voltage and current of ∼26.2 V and ∼2.1 μA, respectively, which were 5-fold higher than that of the nanogenerator with the pure PVDF film. Also, the sensitivity of FPNG upon the irradiation of light was demonstrated by the output voltage reduction of ∼38%, indicating its capability as a light sensing device. Furthermore, the prepared FAPbBr3/PVDF composite was found to be an efficient candidate for light detection applications. A simple planar photodetector was fabricated with the 8.0 wt% FAPbBr3 NP-loaded PVDF composite, which displayed very high responsivity (8 A/W) and response speed of 2.6 s. Thus, this exclusive combination of synthesis and fabrication for the preparation of electro-active films opens a new horizon in the piezoelectric community for effective energy harvesting and light detector applications.

Bio-inspired piezoelectric materials have been considered as excellent energy harvesting source for their non-toxic and biocompatibility nature which have ability to generate and supply significant power to the energy deficient world without any environmental pollution. Till date, fabrication of bio-piezoelectric nanogenerator (BPNG) with high power density and high energy conversion efficiency is of great concern. Here, we have explored the potentiality of an inexpensive and bio-waste porous eggshell membrane (ESM) as an efficient piezoelectric material with piezoelectric strength of ≈23.7 pC/N. The fabricated bio-nanogenerator (ESMBPNG) provides high output voltage (≈26.4 V), current (≈1.45 μA) and high energy conversion efficiency of ≈63% with maximum instantaneous power density (≈238.17 μW/cm 3) under mechanical stress of ≈81.6 kPa. Assembling five ESMBPNGs provides an output voltage of ≈131 V that lights-up more than 90 green LEDs and produced ≈6 μA current in series and parallel connections, respectively, suggesting its effectiveness towards commercialization. Moreover, ESMBPNG is ultrasensitive towards very minute pressure arising from pulse, body motions at rest and walking conditions, water drop, and writing on the device as well. This work would have a significant role towards up-lifting the green energy harvesting technology as self-powered implantable and wearable electronics.

Herein, we demonstrate a facile fabrication of nickel cobalt oxide nanoflake decorated manganese cobalt oxide nanostick-arrays (MnCo2O4.5-NiCo2O4), as a hybrid electrode material through multistep hydrothermal protocols for high performance power device applications. Iron oxide nanoparticles decorated reduced graphene oxide (Fe-rGO) was synthesized through a simplistic reduction process of GO. The morphological features, specific surface areas and morphology dependent electrochemical activity of the as-prepared electrode materials have been investigated systematically. Our as-prepared manganese cobalt oxide/nickel cobalt oxide, MnCo2O4.5-NiCo2O4 (abbreviated as MCO/NCO) hybrid electrode reveals a highest specific capacitance (Cs) value of ∼2506 F g−1 as compared to the base MnCo2O4.5 (∼1220 F g−1) at 1 A g−1 constant current density. The higher Cs values of the hybrid composite can be credited to the synergistic property of MCO and NCO, which eventually facilitates electron transportation. In contrast, Fe-rGO shows a Cs value of ∼236 F g−1 at 1 A g−1. Moreover, an advanced asymmetric supercapacitor (ASC) device was fabricated utilizing MCO/NCO as positive and Fe-rGO as a negative electrode in presence of a potassium hydroxide (KOH) soaked laboratory Whatman 40 filter paper as separator. The device exhibits a Cs value of 170.8 F g−1 at 1 A g−1 together with a decent energy density of ∼34 Wh kg−1 (power density of 597.18 W kg−1 at 1 A g−1) and a longtime cyclic stability (90% Cs retention after 3000 Galvanostatic charge-discharge series). These results suggest superior application potential of our ASC for next -generation portable energy storage applications.

Here, we demonstrated an arc shaped flexible triboelectric nanogenerator (TENG) that efficiently harvests asymmetrical mechanical energy for powering several portable electronic devices. Here the fabrication of TENG is based on the integration of a cigarette wrapper, spongelike poly(vinylidene fluoride) (PVDF) film, and conducting carbon tape. Here, the spongelike PVDF film was prepared through nonsolvent induced phase separation (NIPS) technique (by simply spraying PVDF solution on a water surface in a Petri dish). Owing to the low density of the PVDF sponge and the cigarette wrapper, the final device with a volume of 6.6 cm3 shows a total mass of 1.259 g. The fabricated TENG exhibits open circuit voltage of ∼342 V and short circuit current of ∼8.1 μA on frequencies of ∼3.4 Hz without electrospinning and poling treatment under finger tapping, which gives a maximum area power density of ∼0.37 mW/cm2 at a load resistance of 40 MΩ. The TENG shows excellent durability without any change in output performance...

Extracting energy from various types of mechanical forces through piezoelectric nanogenerator (PNG) exhibits a great potential for powering up low-power portable devices and self-powered electronic systems. Here, the ferroelectric and lead-free perovskite zinc titanate (ZTO) nanoparticles mitigate to align the molecular –CH2/CF2 dipoles of PVDF, promoting the nucleation of electroactive γ-phase in the PVDF matrix (γ-PVDF), which is responsible for the generation of piezoelectricity of the PNG without any electrical poling treatment. The fabricated PNG with 2 wt% ZTO loading shows a maximum output voltage up to ∼25.7 V and current ∼1.2 μA with a power density of ∼8.22 μW. cm−2 under cyclic finger imparting with a constant pressure (∼16.5 KPa). In addition, the PNG is capable of harvesting energy from a wide variety of easily manageable mechanical stress source such as human body movement, walking, and machine vibration and exhibits high durability for about four weeks without any deterioration in the output performance. Furthermore, the ZTO/PVDF films demonstrate a higher electrical energy density of ≈0.267 J cm−3 at an electric field of 600 kV cm−1, which makes it fit for electrical energy storage device. This high performance ZTO/PVDF hybrid film paves a new and effective way to fabricate eco-friendly devices, active sensors, and flexible nanogenerators for powering small portable electronic appliances and flexible high energy density capacitors as well.

Spider silk fibers having remarkable protein sequence structure contain nature's most outstanding mechanical properties and unrivalled elasticity along with biocompatibility and biodegradability. Unfortunately, it remains completely unidentified how the mechanical properties of spider silk effectively contribute to the performance and integrity on piezoelectric nanogenerator. Here, using piezoresponse force microscopy (PFM), we report for the first time structure-dependent piezoelectric response of the spider silk at the molecular level and confirm that silk fiber shows vertical (or out of the plane) piezoelectric coefficient of up to ~ 0.36 pm/V. We also design a mechanically robust piezoelectric nanogenerator (PNG) using nature driven spider silk that exhibits high energy conversion efficiency (≈ 66%), high output voltage (≈ 21.3 V) and current (≈ 0.68 μA) with instantaneous power density of ≈ 4.56 μW/cm2. The fabricated device is biocompatible and ultra-sensitive towards physiological signal monitoring such as arterial pulse response which can be useful for potential biomedical applications.

Here, we demonstrate a facile and substrate-free synthesis of sunflower-like nickel–copper carbonate hydroxide (NC) as electrode material for supercapacitor application, employing a polypyrrolidone assisted hydrothermal protocol. The temperature of the hydrothermal reaction is optimized to achieve high specific surface area with superior electrochemical properties of NC. Owing to the existence of enormous mesopores with high specific surface area (128.6 m2 g−1), the sunflower-like NC exhibits a high specific capacitance (Csp) value of 1185.9 F g−1 at 1 A g−1 with 93.1% initial Csp retention even after 5000 successive galvanostatic charge-discharge (GCD) cycles. Furthermore, an asymmetric device is assembled using this sunflower-like NC as positive and activated carbon as negative electrode with a poly(vinyl alcohol)–potassium hydroxide (PVA–KOH) gel electrolyte membrane as a separator. This work displays the first example of sunflower like nickel copper carbonate hydroxide for the fabrication of ASC device that displays maximum of 32.7 Wh kg−1 energy density, 359.9 W kg−1 power density at 0.6 A g−1 with excellent cyclic stability (88.8% retention after 5000 GCD cycles). The features efficaciously illustrate great prospective of our high performance ASC device for advance electronic applications.

In the present era, the advanced technology demands for the fabrication of light weight and compressible high performance electromagnetic interference (EMI) shielding materials for adaptable shielding application in the area of modern electronic gadgets and telecommunication devices. This study highlights facile fabrication of such lightweight compressible porous polydimethylsiloxane (PDMS)/FRS [Ferrous ferric oxide (Fe3O4) decorated reduced graphene oxide (RGO)/single wall carbon nanohorn (SWCNH)] composite for tunable EMI shielding applications. The Fe powder used to reduce GO, was decorated on the SWCNH and RGO as Fe3O4 during the in situ reaction. FRS dispersed PDMS was allowed to soak and cured in a sugar cube, followed by leaching out of the sugar to obtain highly porous network structure with lightweight and compressible PDMS/FRS composite. The composite possessed an absorption-dominated good comprehensive EMI shielding performance, possibly due to both conductive dissipation and multiple reflections and scattering of EM waves by the inside 3D conductive RGO-SWCNH network with ferromagnetic Fe3O4 nanoparticles. The measurement of attenuation constant and loss tangent describe the absorption property of the composite. The shielding performance of the composite could be simply adjusted owing to its’ pressure induced compressible property, applicable as smart tunable EMI shielding material.

Herein, we highlight the simplistic fabrication of a light-weight, flexible self-charging power pack by the prudent integration of two paper-based high-performance triboelectric nanogenerators (HPTENGs), one commercial semi-flexible photovoltaic/solar cell and a paper-based all-solid-state asymmetric-type supercapacitor (ASSASC) with optimized performance. Each HPTENG unit comprises of a ~20 wt% barium titanate nanoparticles loaded surface micropatterned post-polled PDMS composite (PDMS–20BTO) film-strip impregnated with graphite coated Whatman® 41 filter paper (GFP) as negative and a polypyrrole electrodeposited GFP as positive triboelectric friction layers, respectively. Contrariwise, the ASSASC consists of a nickel-cobalt-molybdenum oxide–graphitic C3N4 hybrid composite coated GFP (NCMO–gCN2/GFP) as positive and a graphitic C3N4 modified reduced graphene oxide coated GFP (gCN–m–RGO/GFP) as negative electrodes, separated by a thin PVA–KOH gel-type electrolyte membrane. Finally, under deformations/stress and illumination of solar light individually on top of our photovoltaic and HPTENGs driven self-charging ASSASC (PTSCASC) power pack, it efficaciously generates electrical energy and consequently stores this generated energy as electrochemical energy for sustainable power supply. Our self-powered PTSCASC# power pack prototype (with two ASSASCs) has been effectually integrated with a medical smart patch for electric pulsatile mediated controlled drug release. Hence, our as-designed self-charging power pack possesses immense potentials for self-powered multifunctional electronics and smart e-healthcare monitoring systems.

The design and fabrication of an alkaline battery-supercapacitor hybrid (BSH) device has been proposed here introducing a hierarchically orientated double hydroxide assembly of cobalt tin hydroxide@nickel hydroxide (CoSn(OH)6@∝-Ni(OH)2) as positive (CTH@NH) and nitrogen, sulfur-doped reduced graphene oxide (NSG) as negative electrode. CTH@NH was obtained through few step time-dependant processes. Double shelled CTH nanocube arrays were obtained by excess alkali etching of intermediate nanocubes that are resulted from fast co-precipitation process at earlier stage. Subsequent growth of ∝-Ni(OH)2 nanoflake upon double shelled CTH nanocube at high pressure and temperature resulted CTH@NH. Improvised core-shell nanodimensional architecture, reduced particle size, mesoporosity and ample surface charges encourage diffusion mediated charge storage with deep flow facility of electrolyte into inner core of electrode material and thus strengthening charge storage capability and capacity which assured significant specific capacity (Cm) of ∼ 1467.24 C g−1 (specific capacitance (Cs): ∼ 2445 F g−1) in the hybrid much higher than CTH (Cm ∼ 480.96 C g−1, Cs of ∼ 801.7 F g−1) at 1 A g−1. The [CTH@NH//NSG] assembled BSH acquired CASC of ∼ 151.5 F g−1 at 1 A g−1 current density with a long term cycling stability of ∼ 95% even after 8000 successive charge-discharge cycles. The concurrent battery performance of CTH@NH along with supercapacitive output of the NSG overcomes the deficiency of specific energy of supercapacitor by providing an excellent specific energy of ∼ 53.8 Wh Kg−1 at a specific power of ∼ 800 W Kg−1 and instigates the high-performance features in the as-fabricated BSH device.

Development of non-toxic, ultra-sensitive, and flexible bio-inspired piezoelectric nanogenerator has become a great challenge for next generation biomedical applications. High performance organic/inorganic materials based piezoelectric nanogenerators suffer from several unavoidable problems such as complex synthesis and high toxicity. Biodegradable and biocompatible piezoelectric material is utmost needed in in-vivo condition to harvest energy for biomedical applications. Here, we report a novel bio-piezoelectric nanogenerator (BPNG) using naturally abundant self-aligned cellulose fibrous untreated onion skin (OS) as efficient piezoelectric material having piezoelectric strength of ∼ 2.8 pC/N. The fabricated OSBPNG generated output voltage, current, instantaneous power density and high piezoelectric energy conversion efficiency of ≈ 18 V, ≈ 166 nA, ≈ 1.7 μW/cm2, and ≈ 61.7%, respectively, and turn on 30 green LEDs by a single device under repeated compressive stress of ≈ 34 kPa and ≈ 3.0 Hz frequency. In addition, maximum output voltage (≈ 106 V) was achieved when 6 units are connected in series, which instantaneously turns on 73 combined LEDs (30 green, 25 blue, and 18 red). OSBPNG is highly effective during throat movement such as coughing, drinking and swallowing. Furthermore, because it works at very low pressure originating from heart pulse or beat, it could be used in pacemakers and health care units. Finally, OSBPNG successfully differentiates speech signals, indicating its potential for speech recognition.

This study describes the preparation of porous poly(vinylidene fluoride) (PVDF)/(ferrosoferric oxide (Fe3O4) decorated polyaniline/single wall carbon nanohorn (SWCNH)) PFC composite through a simple solution blending process using pre-synthesized PFC composite prepared by the in-situ oxidative polymerization of aniline in the presence of SWCNH with FeCl3 as oxidant (also used as the Fe source in the synthesis of Fe3O4) for highly efficient electromagnetic shielding application with high absorption capability. PFC was homogeneously dispersed in the PVDF matrix as conductive nanofiller to develop the conducting network and the porous morphology in the composite was achieved by leaching out of the salt (NaCl) added during solution blending process. The composite shows an excellent EMI shielding effectiveness (EMI SE) due to its porous structure and presence of continuous conductive network (polyaniline-SWCNH) and ferromagnetic Fe3O4 nanoparticles. Moreover, the highly conductive (∼2.5 × 10−2 S cm−1) PVDF-PFC composite (2 mm thickness) has greater dielectric loss and permeability property with a high EMI SE value (≈−29.7 dB) at very low loading (10 wt %) of PFC and SWCNH (1 wt%) in extended Ku-band region. The microwave absorption value also exceeds the reflection as the incident microwaves reflected and scattered multiple times internally and dissipated by the conductive 3D network of SWCNH and polyaniline throughout the composite pore wall.

Fabrication of environmental friendly, compact and wearable electronic device using a flexible substrate that synchronously harvests and stores energy by the co-ordination of a conventional energy harvesting and storage mechanism in a single portable device is highly essential to design modern electronics. Here, for the first time, we highlight the fabrication of a natural bio-piezoelectric driven self-charging asymmetric supercapacitor (SCASC) power cell consisting of nickel-cobalt double hydroxide nanoplies decorated copper oxide nanoflakes substantially grown on a flexible copper foil (NiCoOH-CuO@Cu foil) as a binder free positive electrode and reduced graphene oxide coated copper foil (RGO@Cu foil) as negative electrode with a PVA–KOH gel electrolyte soaked perforated fish swim bladder as natural bio-piezoelectric separator (BPES). The prompt and self-charging behavior of the power cell was established by mechanically deforming it under human finger imparting and by several casual natural body motions. The rectification-free SCASC device can be charged up to 281.3 mV from its initial open circuit potential (~130.1 mV) in ~80 s under continuous human finger imparting at a frequency of 1.65 Hz. Moreover, eight serially connected SCASC devices can instantaneously light-up four red light-emitting diodes (LEDs) and power-up various portable electronic appliances on frequent imparting. Thus, the light-weight SCASC with unique design resembles its desirability for future generation smart and wearable electronics.

Here, we demonstrate synthesis of grass-like cobalt vanadium oxide hydrate (CVO) nanocanes arrays followed by decoration of CVO by iron oxide nanospheres (FeO@CVO) using iron nitrate and CVO through a cost-effective hydrothermal method. Finally, a high-performance robust mesoporous hybrid composite electrode (PPy/FeO@CVO) was fabricated through wrapping up of polypyrrole (PPy) over FeO@CVO using low-temperature in-situ oxidative polymerization of pyrrole. Electrochemical studies of PPy/FeO@CVO with 1 M KOH reveals highest specific capacitance of ∼1202 F/g with exceptionally high cyclic stability at 1 A/g in a three-electrode configuration. Furthermore, a two-electrode based asymmetric supercapacitor using PPy/FeO@CVO as positive and graphene nanoplates (GNP) as negative electrodes and KOH-soaked paper as a separator reveals an outstanding energy density of 38.2 Wh/kg (power density 700 W/kg at 1 A/g) with amazing cyclic stability (95% capacitance retention after 5000 cycles), suggesting great prospective ...

In this study, the electrochemical performance of a polyaniline-based porous ternary composite (PNHFeG) electrode material is reported for a high-performance supercapacitor. The PNHFeG ternary composite was prepared through in situ oxidative polymerization of aniline in the presence of a binary composite NHFeG that involves the combination of flower-like nanostructured Ni(OH)2 and iron oxide-doped reduced graphene oxide (Fe-RGO). The porous ternary PNHFeG composite with high surface area (239 m2 g−1) notably exhibits maximum specific capacitance (C sp ) of 2714 F g−1 at 5 A g−1 current density, along with 98.5% retention of its initial capacitance even after 2000 cycles. Moreover, even at a higher current density of 30 A g−1, the composite electrode material maintains a remarkable C sp value of 1223 F g−1. Finally, the PNHFeG electrode material reveals a power density of 1498 W kg−1, along with a maximum energy density of 135.7 Wh kg−1 at 5 A g−1, suggesting that the current composite electrode material can be considered as a promising candidate for high-performance supercapacitor applications.

We highlight the design and fabrication of a polydimethylsiloxane (PDMS) encapsulated advanced all-solid-state asymmetric supercapacitor (ASC) device consisting of hierarchical mesoporous zinc-iron-cobalt ternary oxide (ZICO) nanowire coated nickel (Ni) foam (ZICO@Ni foam) as a promising positive electrode and nitrogen doped graphene coated Ni foam (N-G@Ni foam) as negative electrode in the presence of PVA-KOH gel electrolyte. Owing to outstanding electrochemical behavior and ultrahigh specific capacitance of ZICO (≈ 2587.4 F/g at 1 A/g) and N-G (550 F/g at 1 A/g) along with their mutual synergistic outputs, the assembled all-solid-state ASC device exhibits an outstanding energy density of ≈40.5 Wh/kg accompanied by a remarkable long-term cycle stability with ≈95% specific capacitance retention even after 5000 charge-discharge cycles. The exclusive hierarchical ZICO nanowires were synthesized by a facile two-step process comprising of a hydrothermal protocol followed by an annealing treatment on a quartz substrate. While Zn

Metal Organic Framework (MOF) based supercapacitors are one of the best energy storage devices for future portable electronics. In this study, we report in detail the design and low-cost fabrication of an advanced asymmetric supercapacitor (ASC) which was assembled with a Prussian blue (PB)/MnO2 (PB@MnO2) hybrid as the positive electrode and a polyaniline (PANI)/graphene nanoplatelet (GNP) (PG) composite as the negative electrode with aq. KNO3 electrolyte. Both the electrodes were made by the coating of the respective electrode materials on conducting stainless steel (SS) fabric. The MOF based positive electrode material, i.e., the PB@MnO2 hybrid was synthesized via reducing agent assisted chemical bath deposition of MnO2 nanolayers on faradaic PB microcubes and showed an appreciable specific capacitance (Csp) of 608 F g−1 at 1 A g−1 current density in the three-electrode measurement and the assembled PB@MnO2//PG ASC device manifests favourable Csp of 98 F g−1 at 1 A g−1. Moreover, this ASC device exhibits significant energy density of 16.5 W h Kg−1 at the power density of 550 W Kg−1 along with notable long-term cycling stability (retention of 93% capacitance even after 4000 cycles of charging and discharging). Thus, the obtained results reflect the great potential of the ASC device for exploring state-of-art futuristic applications as an advanced energy storage system.

To avoid the interference of electromagnetic radiation from other devices, an electronic device needs to be fabricated with flexible and light weight electromagnetic interference (EMI) shielding materials with high efficiency. According, highly flexible porous poly(vinylidene fluoride) (PVDF)/PFR (Fe3O4 decorated polyaniline/RGO composite) composite was prepared through solution blending of PVDF with pre-synthesized PFR conductive composite that involves in-situ oxidative polymerization of aniline in the presence of reduced graphene oxide (RGO) using FeCl3 as oxidant. The porous morphology of the composite was created by leaching out of mixed NaCl from the composite. Polyaniline and RGO were mutually decorated by chemically in-situ synthesized ferrosoferric oxide (Fe3O4) using the Fe source of FeCl3. A homogeneous dispersion of PFR in insulated PVDF matrix resulted in a highly electrical conductive composite (PVDF-PFR) material through formation of three dimensional continuous conductive networks of polyaniline-RGO in the matrix phase. The composite shows an outstanding EMI shielding effectiveness (EMI SE) property due to the porous structure and the presence of conductive network and ferromagnetic Fe3O4 nanoparticles. The PVDF-PFR composite (0.5 mm thickness) depicts a great permittivity and permeability value and achieve high EMI SE value (≈–28.18 dB) and conductivity value of ≈1.10·10–1 S·cm–1 at very low loading (5 wt%) of RGO.

Here, we have fabricated a piezoelectric nanogenerator (PENG) composed of a Co-oxide (Co3O4) doped electro active PVDF based nanocomposite for efficient piezoelectric energy harvesting application where the Co3O4 inclusion favours nucleation and polar β-phase stabilization in the nanocomposite. The morphological effect on the nucleation and β-phase stabilisation of PVDF has been explored experimentally. The flake-like morphology of Co3O4 nanoparticles, synthesized by using a MOF, has a more effective surface area to nucleate and stabilise the β-phase of PVDF than that of rod-like (hydrothermal) and spherical (commercial) nanoparticles. The PENG with PVDF and the 1.5 wt% MOF based Co3O4 (MPNG) shows an excellent open circuit voltage (∼37 V) and short circuit current (∼0.711 μA) upon human finger tapping. The maximum power density generated from the MPNG is ∼8.55 μW cm-2, which is well sufficient for the driving of portable electronic devices like LEDs, calculator wrist watches, humidity sensors etc. Also, from various easily accessible mechanical and biomechanical energy sources like heel pressing, walking, and machine vibration, the MPNG is capable of harvesting energy.

At the moment, we are standing at the edge of exploring conducting nanofillers-based polymer composites and their multifunctional applications which changed the modern science in new direction. Among the several nanofillers, two-dimensional graphene sheet changes the scientific research in new angle with huge applications. The excellent electrical, thermal, and mechanical properties of graphene and their derivatives play a most important role in different fields of applications and increased its demand in modern science. Here, basically, we have looked out various applications of graphene, history of graphene, effectiveness of graphene, and its various derivatives in modern science. The properties of graphene also depend on modification of graphene; it can be chemical modification or physical modification.

Harvesting mechanical energy from the ambient environment with piezoelectric nanogenerators (PENGs) consisting of piezoelectric nanoparticles (NPs) and flexible polymer has drawn considerable attention for developing self-powered electronic devices. Here, a flexible, lead-free, solution processable PENG, composing piezoelectric ZnSnO3 NPs and plasticized PVC was fabricated by a simple solution casting method. The nanogenerator shows a VOC of ∼40 V, a ISC of ∼1.4 μA, and an overall power density more than ∼3.7 μW cm–2 at 35 wt % loading of ZnSnO3, and these values are the highest reported so far in the literature on the cubic ZnSnO3-based nanogenerator. We utilized the generated power for powering seven different color LEDs without any external energy storage unit. Also, the nanogenerator could charge a commercial capacitor (2.2 μF) to ∼6.7 V in ∼129 s, which can be used for powering wristwatch, mobile LCD screen, and calculator.