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In the present investigation, gold NPs (Au-NPs) were synthesized via seed decoction of Nigella sativa, in which, the aqueous seed extract of Nigella sativa acted as a reducing agent as well as coated on Au-NPs surface. Herein, an attempt was made to develop a rapid and biocompatible method to synthesize gold NPs by phytofabrication for anti-diabetic applications. The Nigella sativa seed extract and the Au-NPs synthesized using Nigella sativa exhibited a good antioxidant property, which was determined by the 2, 2- Diphenylpicrylhydrazyl (DPPH) scavenging activity assay. These Au-NPs exhibited 78 % of anti- diabetic property, which was confirmed by α- amylase method. The synthesized nanoparticle Au-NPs size was confirmed by using SEM and TEM. The functional groups (thymoqninone) present in the seed extract as well as Au-NPs were analysed by FTIR. The major functional group i.e. thymoquinone was confirmed by the anthraquinone test and it is responsible for the antioxidant, anti-diabetic, and anticancer properties of the Au-NPs. The phytochemical based nanoparticle prepared in this work showed efficient anti-diabetic activities and it can be considered for the medical applications. In addition, phytochemical based nanoparticle synthesis is safe, eco-friendly, biocompatible, and cost effective.

In this work, the catalytic activity towards hydrogen evolution reaction (HER) was studied for hydrogen adsorption on Pt doped Fe2C (001) surface configuration (Pt/Fe2C) and compared with pure Pt (001). The adsorption of H on the pristine Fe2C, Pt doped Fe2C, and pure Pt in (001) slab was computed. The best and promising HER activity (ΔGH∗ = −0.02 eV) is obtained at the hollow site adsorption of Pt/Fe2C (Fe13Pt3C8) compared to the experimental value of pure Pt (ΔGH∗ = −0.09 eV) suggesting the possibility of the H2 formation on the surface of Fe13Pt3C8. The structural stabilities of Fe2C and Pt/Fe2C were investigated by the formation energy analysis. Also, it is observed that to enhance the HER mechanism, the modification of the d-electron structure of Pt atoms is essential which can be achieved by the increased Pt doping. The Bader charge analysis demonstrated the charge transfer between the substrate and the adsorbed H atoms. The density of states (DOS) of pure Fe2C and optimal Pt/Fe2C were calculated which revealed the magnetic and metallic nature of these materials. In addition, the adsorption and resulted activation of H2 were facilitated by the elongation of H–H bond length in Fe13Pt3C8. This work supports the HER over single atom catalysts (SACs) with lower Pt loading but with high catalytic activity and the maximum atom utilization of SACs.

The goal of the review series on the H2 economy is to highlight the current status, major issues, and opportunities associated with H2 production, storage, transportation, distribution and usage in various energy sectors. In particular, Part I discussed the various H2 (grey and green) production methods including the futuristic ones such as photoelectrochemical for small, medium, and large-scale applications. Part II of the H2 economy review identifies the developments and challenges in the areas of H2 storage, transportation and distribution with national and international initiatives in the field, all of which suggest a pathway for establishing greener H2 society in the near future. Currently, various methods, comprising physical and chemical routes are being explored with a focus on improving the H2 storage density, capacity, and reducing the cost. H2 transportation methods by road, through pipelines, and via ocean are pursued actively in expanding the market for large scale applications around the world. As of now, compressed H2 and its transportation by road is the most realistic option for the transportation sector.

Transition metal dichalcogenides (TMDs) like Molybdenum disulfide (MoS2) are confessed as an effective energy storage materials due to their 2D structure analogues to graphene. Robust 3D architectures of graphene oxide-polypyrrole (GO-PPy) and molybdenum disulfide-polypyrrole (MoS2-PPy) were fabricated by facile, one pot chronoamperometry method to achieve scalable, conductive additive free and binder free supercapacitor electrodes. The electrodeposited GO-PPy and MoS2-PPy electrodes exhibit the specific capacitance of 271 F g−1 and 130 F g−1 respectively at a current density of 1 A g−1. The introduction of reduced graphene oxide (rGO) in PPy matrix offered high capacitance, whereas graphene analogue MoS2 improved the structural stability. Pronounced cycling stability (>2000 cycles) and note-worthy capacitive retentions were also displayed by these composites. MoS2-PPy and GO-PPy retain 82 and 64% of its initial capacitance respectively. These findings are backed up by the correlation of structure and electrochemical performance of GO-PPy and MoS2-PPy.

Cellulose is a very abundant polymer that is found in nature. Cellulose has been used as a raw material for production of biofuels for many years. However, there are multiple processing steps that are required so that cellulose can be used as a raw material for biofuel production. One of the most important steps is the breakdown of cellulose into intermediate sugars which can then be a viable substrate for biofuel production. Cellulases are enzymes which play a role in the catalysis of the breakdown of cellulose into glucose. Nanomaterials and micromaterials have been gaining a lot of attention over the past few years for its potential in immobilizing enzymes for industrial procedures. Immobilization of enzymes on these nanomaterials has been observed to be of great value due to the improvement in thermal stability, pH stability, regenerative capacity, increase in activity and the reusability of enzymes. Similarly, there have been multiple reports of cellulase enzymes being immobilized on various nanoparticles. The immobilization of these cellulase enzymes have resulted in very efficient processing and provide a great and economic solution for the processing of cellulose for biofuel production. Hence in this paper, we review and discuss the various advantages and disadvantages of enzymes on various available nanomaterials.

In this chapter, a few interesting findings on renewable carbons derived from various biomass precursors and their electrochemical applications, especially supercapacitors and lithium-ion batteries were discussed. Electrochemical energy storage devices are progressively crucial since it helps in a significant reduction in the use of different fossils-based resources. The use of energy storage devices in a particular system rests on the nature of the electrode materials. Among an extensive range of electrodes, biomass-based carbons have gained significant consideration as an electrode because of their variable physicochemical features, environmental concern, and commercial value. We have also discussed a few recent developments of biomass-derived carbons and some important techniques such as carbonization and activation conditions that control their property and performance of carbon electrodes. Besides, some of the parameters such as pore structure, surface property, and degree of graphitization, which regulate the electrochemical functioning of the device were discussed in detail. In the final section of this chapter, we included some energy storage applications of biomass-based carbons, and their effectiveness as an electrode were summarized. In brief, this chapter provides a fundamental understanding of several biomass-derived carbon materials and suggests the essential strategies for the fabrication of various energy storage systems.

Supercapacitor electrodes comprising of conjugated conducting polymers (CPs) and metal oxides have become the focus of scientific research due to their high specific capacitance, low equivalent series resistance and high density with better cyclic stability. A 3D architecture is fabricated using polypyrrole and lead oxide as the building blocks by a facile, one pot chronoamperometry method to achieve a conductive additive free, binder free and scalable supercapacitor electrode. The superior electrochemical properties of the 3D PPy-PbO2 are due to its porous structure, high surface area and high electrical conductivity that endow rapid transportation of electrolyte ions and electrons throughout the electrode matrix. The synergistic effect between the components in a proper ratio improves the supercapacitor performance and material stability. The structure and electrochemical performance of the 3D composite are correlated. The high specific capacitance (330 Fg-1) and impressive cycling stability (>2000 cycles) estimated for PPy-PbO2 open up an opportunity to consider the 3D nanostructures as cutting edge materials for energy storage solutions.

Antimonene is an exfoliated 2D nanomaterial obtained from bulk antimony. It is a novel class of 2D material for energy storage applications. In the present work, antimonene was synthesized using a high-energy ball milling-sonochemical method. The structural, morphological, thermal, and electrochemical properties of antimonene were comparatively analyzed against bulk antimony. X-ray diffractometry (XRD) analysis confirms the crystal structure and 2D structure of antimonene, as a peak shift was observed. The Raman spectra show the peak shift for the Eg and A1g modes of vibration of antimony, which confirms the formation of antimonene. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) images depict the exfoliation of antimonene from bulk antimony. Thermal analysis unveiled the thermal stability of antimonene up to 400 °C with only 3% weight loss. X-ray photoelectron spectroscopy (XPS) analysis reveals the formation of antimonene, which is free from contamination. The electrochemical properties of antimony and antimonene were investigated using cyclic voltammetry (CV) and chronopotentiometric (CP) analysis, using 2 M KOH as an electrolyte. Antimonene exhibited a relatively high specific capacitance of 597 F g−1 compared to ball-milled antimony (101 F g−1) at a scan rate of 10 mV s−1. Moreover, electrochemical impedance spectroscopy (EIS) analysis revealed that antimonene has a relatively low equivalence series resistance (RESR) and low charge transfer resistance (RCT) compared to bulk antimony, which favors high electrochemical performance. The cyclic stability of antimonene was studied for 3000 cycles, and the results show high cyclic stability. The electrochemical results demonstrated that antimonene is a promising material for energy storage applications.

Energy enthusiasts in developed countries explore sustainable and efficient pathways for accomplishing zero carbon footprint through the H2 economy. The major objective of the H2 economy review series is to bring out the status, major issues, and opportunities associated with the key components such as H2 production, storage, transportation, distribution, and applications in various energy sectors. Specifically, Part I discussed H2 production methods including the futuristic ones such as photoelectrochemical for small, medium, and large-scale applications, while Part II dealt with the challenges and developments in H2 storage, transportation, and distribution with national and international initiatives. Part III of the H2 economy review discusses the developments and challenges in the areas of H2 application in chemical/metallurgical industries, combustion, and fuel cells. Currently, the majority of H2 is being utilized by a few chemical industries with >60% in the oil refineries sector, by producing grey H2 by steam methane reforming on a large scale. In addition, the review also presents the challenges in various technologies for establishing greener and sustainable H2 society., Highlights • Industrial applications of H2 with a focus on decarbonization of industry. • H2 usage through fuel cells for mobile and stationary applications. • Combustion of H2 in internal combustion engines and gas turbines. • Major challenges and opportunities towards realizing H2 economy.

The efforts on energy system decarbonization and improved sustainable energy efficiency in developed countries led energy enthusiasts to explore alternative highly effective pathways in accomplishing these goals. Specifically, the transition from hydrocarbon to H2 economy using fuel cells and H2 technologies is a sustainable and favorable approach forward in meeting stationary, transportation, industrial, residential, and commercial sectors. This review in three Parts brings out the capability of H2 for enabling an energy revolution through much-needed flexibility in renewable energy resources. The review identifies the developments and challenges within the H2 generation, storage, transportation, distribution, and usage - as well as applications along with national and international initiatives in the field, all of which suggest a pathway for a greener H2 society. The review also highlights the opportunities and challenges in major energy sectors for H2 technologies. Part I of the series highlights the importance of H2 economy and initiatives from various agencies, and presents several H2 generation methods.

Reduced graphene oxide (RGO) based light weight aerogel scaffolds were prepared using a simple hydrothermal method with ascorbic acid as a reducing agent. Hydroxyapatite was biomimetically mineralized on the surface of these scaffolds by soaking RGO aerogels in simulated body fluid which consists of calcium and phosphorous precursors. The biomimetic mineralization of these samples was also studied after functionalizing RGO aerogelwith various biocompatible polymerssuch as collagen, chitosan and poly-L-glutamic acid. The influence of these polymers towards mineralization were studied using various characterization methods. It was observed that polymer functionalized RGO aerogel exhibited increased rate of mineralization due to the presence of more functional groups which aids in mineralization and growth of apatite. Thus, mineralized spherical apatite was found to be uniformly assembled on the surface and the interior of the aerogel. The electrical properties of these samples were studied using a source meter and the electrical conductivity of these samples varied depending upon the functionalized polymers.

Conducting polymer nanocomposites associated with metal oxides are emerging class of pseudocapacitive materials that exhibit enhanced electrochemical performance in energy storage applications. In this work, we fabricated polyaniline (PANI)/Fe3O4 nanocomposite (PFNC) through the in situ polymerization of aniline in presence of microwave synthesised Fe3O4 nanoparticles. The prepared PFNC was characterised by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The surface morphology was investigated by scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. TEM studies revealed the presence of Fe3O4 nanoparticles wrapped by PANI with size in the range of 40–60 nm. The porous structure is validated by the associated morphology, where the voids are created by the formation of microspheres out of the nanospheres. These spaces boost the electrochemical activity of the PFNC by facilitating more sites for the insertion of electrolytic ions during the electrochemical reaction process. The fabricated PFNC on carbon felt offers the enhanced electrochemical properties and exhibits high specific capacitance (572 F g−1 at 0.5 A g−1), pronounced cycling stability (>5000 cycles at 1 A g−1) with good capacitance retention (82%). An excellent rate performance of 71.9% is also exhibited by the PFNC electrode with ten times the original current density (from 0.5 A g−1 to 5 A g−1). These out-standing characteristics prove that PFNC has a great potential to be exploited as highly efficient electrode materials for supercapacitors.

Recent advances and demands in biomedical applications drive a large amount of research to synthesize easily scalable low-density, high-strength, and wear-resistant biomaterials. The chemical inertness with low density combined with high strength makes h-BN one of the promising materials for such application. In this work, three-dimensional hexagonal boron nitride (h-BN) interconnected with boron trioxide (B2O3) was prepared by easily scalable and energy efficient spark plasma sintering (SPS) process. The composite structure shows significant densification (1.6–1.9 g/cm3) and high surface area (0.97–14.5 m2/g) at an extremely low SPS temperature of 250 °C. A high compressive strength of 291 MPa with a reasonably good wear resistance was obtained for the composite structure. The formation of strong covalent bonds between h-BN and B2O3 was formulated and established by molecular dynamics simulation. The composite showed significant effect on cell viability/proliferation. It shows a high mineralized nodule formation over the control, which suggests its use as a possible osteogenic agent in bone formation., by Chandkiram Gautam , Dibyendu Chakravarty, Amarendra Gautam, Chandra Sekhar Tiwary, Cristiano Francisco Woellner, Vijay Kumar Mishra, Naseer Ahmad, Sehmus Ozden, Sujin Jose, Santoshkumar Biradar, Robert Vajtai , Ritu Trivedi, Douglas S. Galvao and Pulickel M. Ajayan

In this work, a facile one-pot chronoamperometry method was adopted to prepare the three-dimensional (3D) SnO2 incorporated polypyrrole/reduced graphene oxide to achieve high stability and elevated electrochemical properties. A detailed study has been performed to correlate the structure, surface morphology, redox reaction at the electrode and its impact on the suitability of the material. The morphology analysis showed the presence of SnO2 nanoparticles on graphene sheets forming irregular flower-like coarse clusters, consisting of spinule-like structures on the surfaces that are embedded in polypyrrole matrix. The electrochemical performance reveals that SnO2-PG exhibits a high specific capacitance of 330 F g−1 at a current density of 1 A g−1 in 1 M KCl electrolyte and an excellent cycling stability of 82% even after 2000 cycles, a significant value for polymer nanocomposite. The existence of a high degree of porosity, considerably improved active surface area and the conductivity of SnO2-PG facilitated the better ionic penetration which demonstrates a new architecture for high performance supercapacitor.

Reduced Graphene Oxide aerogels (A-RGO), functionalized with chitosan, were found to induce and/or accelerate the mineralization of hydroxyapatite. The functionalized chitosan acts as a soft interfacial template on the surface of A-RGO assisting the growth of hydroxyapatite particles. The mineralization on these soft aerogel networks was performed by soaking the aerogels in simulated body fluid, relative to time. Polymer-induced mineralization exhibited an ordered arrangement of hydroxyapatite particles on reduced graphene oxide aerogel networks with a higher crystalline index (IC) of 1.7, which mimics the natural bone formation indicating the importance of the polymeric interfacial template. These mineralized aerogels which mimic the structure and composition of natural bone exhibit relatively higher rate of cell proliferation, osteogenic differentiation and osteoid matrix formation proving it to be a potential scaffold for bone tissue regeneration.

The emerging miniaturized energy storage devices focus on wearable, flexible, and portable electronic devices with high energy density, fast energy transfer capability, long charge-discharge cycles, and low cost. In the present work, a one-step chronoamperometry technique was used to fabricate the three-dimensional ternary architecture of iron oxide embedded polypyrrole-rGO matrix (Fe-PrGO) and the corresponding binary (PrGO) and unary (PPy) to have a comparative study on the enhancement of the capacitance. A thorough investigation was carried out to interpret the crystal structure, composition, material morphology, and electrochemical performance. The structure-property-performance correlation was analysed for realising the suitability of the prepared hybrid nanocomposites as electrode materials. The prepared electrode showcased a specific capacitance of 442 F g−1 in an aqueous electrolyte (1 M KCl) at a current density of 1 A g−1. The Fe-PrGO electrode displayed a good cycle performance with 88% of the original capacity retained over 8000 cycles that may be attributed to the superior ion-transport kinetics offered by the synergistic effect of properly selected components. Our study confirms that Fe-PrGO offers an effective solution to enhance the preparation of metal oxide based low-cost environmentally benign flexible supercapacitors to power the virtual health-care devices that become a permanent outcome of the COVID-19 pandemic and flexible supercapacitor for long cycling applications

In recent years, several innovations and studies have been remarked to develop carbon-based nanocomposites and their applications. Carbon-based materials have received increased attention in every category, including the energy sector, water purification, and biomedical. Besides, carbon and its derivatives are well-known for their remarkable features such as high conductivity, surface area, excellent chemical, and mechanical stability. On the other hand, transitional metal oxides (TMO) and conducting polymers (CPs) are renowned for their docility, low price, and reliable performance. In general, the carbon electrodes functioning was reported to improve considerably by homogeneous blending of TMO and CPs. This approach results in developing excellent electrode material that can deliver high-performance functional composites for electrochemical energy storage systems. In this review, we discussed the synergistic effect and the resulting performance of functional carbons considering features like morphology, surface area, and other parameters that influence the activity of functional carbons and their electrochemical studies.

A high sensitive electrochemical sensor was designed for the real time detection of dopamine (DA) and uric acid (UA) by using the Nanocomposite (NC) of reduced graphene oxide nano-octahedral shaped Mn3O4 modified Glassy Carbon Electrode (rGO/Mn3O4/GCE). The effect of Mn3O4 on the electrochemical and physical properties of rGO/Mn3O4 NC by Mn3O4 contents was analyzed by varying the molar ratio of Mn precursor (1, 5 and 10 mM denoted as GM1:1, GM1:5 and GM1:10 respectively). Due to the unique morphology and physical properties originated from Mn3O4, GM1:10/GCE revealed enhanced electrochemical response in terms of large peak potential separation, high selectivity and sensitivity. The GM1:10/GCE displayed a distinct SWV response to DA and UA for 1–600 μM at lowest detection limit of 1.42 μM and 0.76 μM. Additionally, anti-interference property of the designed sensor against electroactive molecules is found to be excellent stability and good reproducibility. Finally, it was make use for the detection of DA and UA in the pharmaceutical compound and physiological residue.

Quantum chemical calculations of energy and geometrical parameters of 1-aminoisoquinoline [1-AIQ] were carried out by using DFT/B3LYP method using 6-311G (d,p), 6-311G++(d,p) and cc-pVTZ basis sets. The vibrational wavenumbers were computed for the energetically most stable, optimized geometry. The vibrational assignments were performed on the basis of potential energy distribution (PED) using VEDA program. The NBO analysis was done to investigate the intra molecular charge transfer of the molecule. The frontier molecular orbital (FMO) analysis was carried out and the chemical reactivity descriptors of the molecule were studied. The Mulliken charge analysis, molecular electrostatic potential (MEP), HOMO-LUMO energy gap and the related properties were also investigated at B3LYP level. The absorption spectrum of the molecule was studied from UV–Visible analysis by using time-dependent density functional theory (TD-DFT). Fourier Transform Infrared spectrum (FT-IR) and Raman spectrum of 1-AIQ compound were analyzed and recorded in the range 4000–400 cm−1 and 3500-100 cm−1 respectively. The experimentally determined wavenumbers were compared with those calculated theoretically and they complement each other.

Quantum chemical calculations on energy and molecular structure of 2-amino-3-methyl-5-nitropyridine (2A3M5NP) have been attempted by implementing DFT/B3LYP method using 6-311G (d,p), 6-311G++ (d,p) and cc-pVTZ basis sets. The optimized geometry and the vibrational analysis for energetically most stable configuration, are carried out theoretically by using B3LYP/cc-pVTZ basis set. The computed vibrational frequencies were scaled by using scaling factors and compared with the experimental Fourier Transform Infra-Red (FTIR) solid phase spectrum in the region 4000-400 cm−1 and FT-Raman spectrum in the region 4000-100 cm−1. The complete vibrational assignments, analysis and correlation of fundamental modes of the compound have been carried out using the potential energy distribution (PED). The intramolecular charge transfer, hyperconjugative interaction of the compound is investigated from natural bonding orbital (NBO) analysis. The UV-Visible spectrum of 2A3M5NP was obtained with ethanol as a solvent. The electronic properties such as HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) energies are determined by B3LYP/cc-pVTZ basis set. The electronic absorption spectrum of the compound was studied from UV-Visible analysis by using time-dependent density functional theory (TD-DFT). The electron density distribution and chemical reactive sites of 2A3M5NP were analyzed from molecular electrostatic potential (MEP) analysis and frontier molecular orbital (FMO) analysis.

Electrode materials with high efficiency in ionic and electronic transport are essential for high performance supercapacitors. Even though MnO2 is demonstrated as a promising material for supercapacitors due to its excellent electrochemical performance and natural abundance, its wide application is limited by poor electrical conductivity. Inspired by the electrochemical activity and electrical conductivity of ZnO, a highly porous three dimensional nanostructure of Mn/Zn bimetallic oxide was synthesized by microwave irradiation technique for the first time. The crystal structure, morphology and chemical composition and electrochemical properties of the Mn/Zn bimetallic oxide were investigated. The bimetallic oxide exhibits a high specific capacitance of about 250 F g−1 even after 5000 charge/discharge cycles at current density of 0.5 A g−1. A possible correlation of the structure of the bimetallic oxide to its electrochemical performance is also proposed.

In this work, we report the reduction of chromium concentration in the polluted groundwater samples from Madurai Kamaraj University area, India, where the dissolved salts in groundwater are reported as serious health hazards for its inhabitants. The water samples have intolerable amounts of total dissolved solids (TDS) and chromium is a prominent pollutant among them. Chromium reduction was achieved by treating the polluted groundwater with PANI/Fe3O4 nanocomposites synthesized by in situ polymerization method. Further experimentation showed that the nanocomposites exhibit better chromium removal characteristics upon increasing the aniline concentration during the synthesis. We were able to reduce chromium concentration in the samples from 0.295 mg L−1 to a tolerable amount of 0.144 mg L−1. This work is expected to open doors for chromium-free groundwater in various regions of India, when improved to an industrial scale.

Nanoparticle assisted therapeutics is an intensive area of interest among research communities but also pose serious questions of concern related to environment and its interactions in-vivo. Chitosan based vectorized biodegradable capsules had been widely studied as drug delivery systems and much more. Irrespective of the herculean tasks accompanied by several research communities over the aspect of translational nanomedicine, we still have a long way to go before any leap towards this common goal. Here we present our investigations over the generation of excited oxygen in a natural drug Curcumin as a result of interaction between chitosan polyelectrolyte microspheres surface decorated with nano silver. This could act as a potential system for applications related to photo dynamic therapy. The nano silver decorated Chitosan/TPP microcapsules induces two fold enhancement in the generation of Singlet Oxygen in Curcumin under UV irradiation. The Transmission Electron Microscopic images revealed that silver nano particles on the surface of the polyelectrolyte spheres were of spherical geometry, 16 nm in size and was uniformly arranged over the surface of the sphere.

Europium doped hydroxyapatite (EDA) nanorods with various concentrations of ionic silver functionalized on its surface were prepared using a facile hydrothermal method. Enhancement and quenching in luminescence of europium was observed depending upon the concentration of silver ions. The antibacterial activity of the samples with various concentrations of silver was studied and it was observed that the antibacterial activity increased with increase in concentration of silver ions. These ionic silver functionalized EDA nanorods were found highly biocompatible to L929 fibroblast cells but were toxic to MCF-7 breast cancer cells indicating that these nanoparticles can be effectively used for theranostic applications.

In this study, benzoyl-hydrazine anchored graphene oxide (BHGO) is synthesised using graphene oxide (GO) and benzoyl hydrazine (BH) via a simple, cost effective ultrasonic assisted chemical route. BH acted as a nitrogen source, reducing agent, and morphology modifier resulting in good electrochemical performance of BHGO. The supercapacitor behaviour of BHGO is investigated in different aqueous electrolytes and it exhibits a specific capacitance of 170 F g−1 at a current density of 1 A g−1 in 1 M H2SO4 and capacitive retention of 85% over 5000 cycles at 5 A g−1. This high performance is attributed to the enrichment of electroactive sites of GO through nitrogen moieties enhancing faradaic redox reactions and thereby the polarization at the electrode surface.

Nanowires of α-MnO2 coated phosphate anion intercalated carbon materials are synthesized using a simple hydrothermal method and characterized for its structure, composition, morphology, surface area, and electrochemical properties. The prepared material exhibits a specific capacitance of 362 F g−1 (areal capacitance of 212 mF cm−2) at a current density of 1 A g−1 in 1 M Na2SO4 electrolyte. The intercalated phosphate anions create more active sites for the enhanced reactivity and inhibit the dissolution of MnO2 during charge-discharge. The electrode offers a long cycle life with 80% capacitance retention for more than 2000 cycles. The core-shell structured nanowire morphology provides the best rate capability, high stability, and low charge transfer resistance which favour good supercapacitor performance.

Spinel LiMn2O4 has been gaining more attention for supercapacitor applications due to its abundance, low cost, environmental friendliness, and high energy density as well as good rate capability. In this work nanostructured multimetal oxide LiMn2O4 was synthesized using expeditious, eco-friendly, glucose mediated simple microwave irradiation method. A detailed study has been performed to correlate the phase structure, surface morphology, redox reaction at the electroactive species and its potential impact on the electrochemical performance as the electrode material. The synthesized spinel LiMn2O4 electrode exhibits a good specific capacitance of 276 F g −1 and 220 F g−1 in aqueous (KOH) and non-aqueous (LiClO4/ethylene carbonate (EC)) electrolytes respectively at a scan rate of 20 mV s−1. In aqueous electrolyte, the reaction kinetics of supercapacitors became very fast which is responsible for the exhibited high capacitance. Excellent capacitance retention of 90% even after 2000 cycles was achieved for this spinel structure. This indicates that the aqueous electrolyte and unique spinel structure are favourable for superfast redox kinetics of the prepared LiMn2O4 due to its higher ionic conductivity and electrochemical stability.

In this study, a novel polypyrrole (PPy)/reduced graphene oxide (rGO)/lead dioxide (PbO2) nanocomposite (PGPb) has been successfully fabricated by a one pot cathodic electrodeposition method for the first time and characterized systematically. The fabricated electrode exhibited an enhanced electrochemical capacitance of 514 F g−1 and a capacitance retention of 86% even after 4000 cycles at a current density of 1 A g−1. The enhanced specific capacitance, rate capability, and cycling performance are ascribed to the rapid transferring path for electrons and ions and the structural integrity and stability endowed by synergy.

Solid state rare earth nanoperovskites La(1-x)SmxCrO3 (x = 0 and 0.1) have been synthesized through ball milling method. Powder X-ray diffractogram confirms the effect of Sm3+ magnetic dopant in the formation of polycrystalline, single phase, orthorhombic LaCrO3 with reduced crystallite size. Enhanced antiferromagnetic nature with decrease in the magnetic ordering temperature (TN) has been analyzed using isothermal and field cooling magnetization studies in the temperature range of T = 300 K–5 K. The X-ray photoelectron spectroscopy determines a quantitative analysis of the oxidation states and the corresponding physicochemical interactions of the cations. It also substantiates the observed distortions incurred as an effect of samarium dopants onto the crystal lattice structure. Temperature dependent dielectric analysis for the rare earth orthochromites exhibits negligible dielectric loss, improved dielectric constant and decreased resistance for doped system. The magnitude of resistivity reduces due to the charge localization with the semiconductor to insulator transition temperature at TSI = 11 K. The observed enhancement in La(1-x)SmxCrO3 physical properties is mainly ascribed to the coupling of magnetic moments and CrO6 octahedral distortion induced polarization upon occupancy of relatively smaller ionic radii rare earth atoms in the orthorhombic crystal structure.