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Optimization of suitable electrode material flashing high electrochemical performance is the main hindrance in energy storage applications. Metal oxide-based electrode materials are promising candidate which greatly promotes the sustainable development. Herein, strontium oxide (SrO) is synthesized from sonochemical method followed by calcination. Incorporating polyaniline (PANI) and graphene (Gr) intensify the materials performance. Three asymmetric devices are designed using SrO, its composites (SrO/PANI and SrO/PANI/Gr) and activated carbon (AC) as an electrode and electrolyte-soaked separators are sandwiched in solidly packed cell assembly. Electrochemical measurements are performed to scrutinize the inherent properties. After that, Dunn’s model is applied to evaluate the capacitive and diffusion-controlled contributions. The obtained result divulges that SrO/PANI/Gr//AC exhibits more diffusive-controlled contribution and reveals a battery type behavior due to the contribution of PANI in redox reactions. Thus, this work delivers a route to synthesize metal oxides-based composites and a systematic approach to analyze the charge storage mechanism in asymmetric supercapacitors.

Charge carrier modulation of graphene-based field effect transistors (GFETs) is the key factor to utilize and enhance its fascinating properties for technological applicability. Here, we have demonstrated the gate-dependent tweaking of electrical properties of graphene devices by application of honey as a top gate dielectric. Electrical characterization of dual-gated GFET is elucidated at different top and back-gate voltages. A charge neutrality point is fine-tuned by varying the top gate voltage (Vtg) from + 3 to − 4 V. The change in carrier density is clearly observed from 3.66 × 1012 to 2.15 × 1011 cm−2 at + 3 to − 4 Vtg. The charge carrier mobility of gel-gated GFET is increased significantly to 5376 cm2/V ⋅ sec by increasing top-gate voltages up to − 4 V. Result demonstrates a cost-effective, facile and rapid fabrication of top-gated devices and suggest natural dielectric materials as good candidate to replace conventionally available gate dielectrics in FET technology.

A facile methodology has been adopted for the synthesis of cobalt oxide (Co3O4) by wet chemical technique followed by the calcination and prepared Co3O4/C composite for energy storage devices. Initially, SEM and XRD are carried out to analyze the surface characterizations of electrode material. The electrochemical properties of synthesized material has been investigated and the maximum specific capacitance of 567 F/g is achieved for Co3O4/C composite at 3 mV/s scan rate. Co3O4/C composite and activated carbon (AC) are sandwiching and separated with PVA-KOH-C gel electrolyte. The device has been examined at several scan rates and current densities demonstrating better performance with maximum energy density of 63 Wh/kg at 0.7 A/g. The capacitive retentivity is 82 % after 6000 charge/discharge cycles. The solid-state devices are showing a tremendous performance with high energy and power density and are safe to handle due to no seepage which can be utilized for the next generation.

Two dimensional (2D) layered materials such as graphene and transition metal dichalcogenides (TMDCs) have gain profound attention owing to their unique electrical, optical, structural and mechanical properties . These novel features make them promising candidate for the next generation optoelectronic and photonic devices . Here, we demonstrated the gate-voltage dependent current modulation of vertical Au/WS 2 /Gr Schottky barrier . A clear rectification is observed in J-V characteristic curves at different gate-voltage due to asymmetric barriers Au/WS 2 and WS2/Gr. The current modulation is obtained by varying the gate-voltage and the extracted rectification ratios ranging from 2.25 × 103 at −60 V to 1.65 × 103 at +60 V, respectively. Furthermore, the junction is utilized for the photo response at several drain to source and gate voltages which reveals modulation in the photocurrent . The photocurrent detected at V ds 0.5 V is ~24 μA that is enhanced to ~52 μA upon varying the Vds to 1 V. Gate tunable photoresponse of the junction depicts that the photocurrent is enhanced from 16 μA at Vg 20 V to ~17 μA at Vg 60 V. Our results demonstrate an effective way to modulate the current of Schottky junction (Au/WS2 /Gr) by employing gate voltage whereas the tunability in the photocurrent unveil its potential applications in next generation photodetectors .

Novel and unique characteristics of graphene have received much attention in energy conversion and storage devices. Graphene based hybrid structures have been employed for a wide variety of efficient and durable fuel cell energy systems. Here, the review focuses on the components of fuel cell device and utilization of graphene in modern fuel cell technology such as graphene based electrodes, electro-catalysts, electrolyte membrane and bipolar plates. Dispersion of graphene over conductive electrodes provide electrochemically active sites to improve the electrocatalytic activity towards oxidation reduction reaction and fuel oxidation. The main issue regarding the degradation of fuel cell is corrosion of bipolar plates which is also discussed and can be reduced by incorporating graphene based metal composites. Various electrical transport measurements and electrochemical parameters were also studied to evaluate the fuel cell performance. Incorporation of graphene in fuel cell technology exhibit excellent catalytic performance in potential applications of fuel cell devices.

The excellent solution-processability of polymers have provoked the interest for their potential applications in cost-effective electronic devices. However, these devices usually have low mobility. The study manifests an innovative approach to enhance the mobility of polymer-based field effect transistors (FETs) by incorporating graphene as an intervening layer between poly [4-(4,4-dihexadecyl-4H-cyclopenta [1,2-b:5,4b′] dithiophen-2-yl)-alt-[1,2,5] thiadiazolo [3,4-c] pyridine] (PCDTPT) channel and dielectric layer dielectric. An intentional discontinuity in the graphene layer was introduced to affirm the role of polymer as channel and graphene as carrier injector. The results divulge the enhancement in the performance of PCDTPT-graphene and PCDTPT-graphene (discontinuous) device as compare to pristine PCDTPT based FET. A significantly high mobility i.e. 13.08 cm2/V.sec is achieved for PCDTPT-graphene hybrid device which is 32 times higher than that of pristine PCDTPT based FET (0.41 cm2/V.sec). These results signify that the incorporation of atomically thin graphene layer is a novel route for fabrication of high mobility solution-processed polymer-based FETs for next generation cost effective and high performance electronic devices.

Two dimensional (2D) materials based heterostructures have gained profound interest in optoelectronics and electronic technology due to additional functionalities over the individual structures. This study demonstrates the fabrication and characterization of van der Waal heterostructure by selective coverage of graphene (Gr) with tungsten disulfide (WS2). The electrical transport measurements divulge the tweaking of charge carriers in graphene after WS2 coverage. Such architecture provides route towards the formation of heterojunction within graphene FET based on surface charge transfer between Gr/WS2 heterointerface. Furthermore, the exposure of device towards deep ultraviolet light (DUV) enhances the charge transfer mechanism and as a result more pronounced junction is observed. The photoelectrical characterization of heterostructure is also investigated by calculating detectivity (D*), external quantum efficiency (EQE) photoresponsivity (Rλ). Our results suggest that 2D heterostructures in combination with DUV irradiations are more efficient and suitable choice to selectively tune the properties of 2D material-based optoelectronic devices.

An upsurge in sustainable energy demands has ultimately made supercapattery one of the important choice for energy storage, owing to highly advantageous energy density and long life span. In this work, novel strontium based mixed phased nanostructures were synthesized by using probe sonicator with sonication power 500 W at frequency of 20 kHz. The synthesized material was subsequently calcined at different temperature ranging from 200 to 800 °C. Structural and morphological analysis of the synthesized materials reveals the formation of mixed particle and rod like nanostructures with multiple crystal phases of strontium oxides and carbonates. Crystallinity, grain size and morphology of grown nanomaterials significantly improved with the increase of calcination temperature due to sufficient particle growth and low agglomeration. The electrochemical performance analysis confirms the redox activeness of the Sr-based electrode materials. Material calcined at 600 °C show high specific capacitance of 350 F g−1 and specific capacity of 175 C g−1 at current density of 0.3 A g−1 due to less particle agglomeration, good charge transfer and more contribution of electrochemical active sites for redox reactions. In addition, the developed supercapattery of Sr-based nanomaterials//activated carbon demonstrated high performance with maximum energy density of 21.8 Wh kg−1 and an excellent power density of 2400 W kg−1 for the lower and higher current densities. Furthermore, the supercapattery retain 87% of its capacity after continuous 3000 charge/discharge cycles. The device characteristics were further investigated by analyzing the capacitive and diffusion controlled contributions. The versatile strategy of developing mixed phased nanomaterials pave the way to synthesize other transition metal based nanomaterials with superior electrochemical performance for hybrid energy storage devices.