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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.

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.

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.

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.

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.

An attempt has been made to deposit a novel smart ion (Sr, Zn, Mg) substituted hydroxyapatite (I-HAp) and silica nanotube (SiNTs) composite coatings on polypyrrole (PPy) coated surgical grade 316L stainless steel (316L SS) to improve its biocompatibility and corrosion resistance. The I-HAp/SiNTS/PPy bilayer coating on 316L SS was prepared by electrophoretic deposition technique. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies were carried out. These results confirmed the significant improvement of the corrosion resistance of the 316L SS alloy by the I-HAp/SiNTs/PPy bilayer composite coating. The adhesion strength and hardness test confirmed the anticipated mechanical properties of the composite. A low contact angle value revealed the hydrophilic nature. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used for the leach out analysis of the samples. Added to this, the bioactivity of the composite was analyzed by observing the apatite formation in the SBF solution for 7, 14, 21 and 28days of incubation. An enhancement of in vitro osteoblast attachment and cell viability was observed, which could lead to the optimistic orthopedic and dental applications.

A 3D architecture is fabricated using 2D nano-sheets of GO and MoS2 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-rGO–MoS2 (PGMo) are due to its porous structure, thin wall, 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 of PGMo. The possible correlation of the structure and electrochemical performance of the 3D ternary composite is backed by a fully atomistic molecular dynamics (MD) simulation study. The high specific capacitance (387 F g−1) and impressive cycling stability (>1000 cycles) estimated for PGMo open up an opportunity to consider the 3D ternary nanostructures as cutting edge materials for energy storage solutions.

3D (three dimensional) architectures synthesised using an easily scalable solid state method which results in an interconnected network of porous h-BN sheets with boron trioxide are reported in this study. The boron trioxide acts as a nucleating agent for the formation of laterally large nanosheets of h-BN with a low density and increases the specific surface area. The stable form shows improved mechanical properties (experimentally and using MD simulation) and serves as a suitable material for humidity and liquefied petroleum gas (LPG) sensor applications. The sensor shows stability for up to several months without losing its sensitivity.

Hydroxyapatite (HAp) nano-ceramic powder was synthesized successfully via microwave irradiation technique. To study the effect of MgO inclusion on the mechanical properties of pure HAp, its composites with different (0.1, 0.2, 0.3 and 0.5) wt% of MgO were prepared. The influence of sintering temperature on the mechanical properties of pure HAp and its composites with MgO was also observed at 1000, 1100, 1200 and 1300 °C respectively. Samples were characterized by using X-ray diffraction (XRD) to determine the phase stability. The mechanical properties of pure HAp and its composites with MgO were measured using several parameters such as density, Young's modulus, fracture toughness, load bearing capability and porosity. It was revealed that MgO addition significantly enhanced the grain growth as well as the mechanical properties of HAp. The HAp composite modified with 0.5 wt% of MgO sintered at 1200 °C exhibited the best mechanical characteristics. This composite exhibits density of 3.04 g cm−3, Young's modulus of 126.31 GPa, fracture toughness of 178.58 MJ cm−3 and a maximum load bearing capability of 11.61 kN. To authenticate the biocompatibility of prepared biomaterials, the cell viability (MTT assay) was carried out and the mechanically best composite was found to be compatible for biomedical applications.

The aim of the present study was to synthesize CeO2 nanoparticles using plant pathogenic fungus F. solani and also to study the antibacterial activity as well as the influence on the inhibition of biofilm formation against biomedically important bacterial strains namely Staphylococcus aureus, Psedomonas aeriginosa, Escherichia coli and Klebsiella pneumoniae. Thermogravimetric/differential thermal analysis (TG/DTA) suggested a crystallization temperature of the as-synthesized CeO2 nanopowder at 400 °C. Powder X-ray diffraction analysis and Raman spectroscopy substantiated the presence of CeO2 nanoparticles with a cubic fluorite structure. The contribution of functional groups corresponding to the F. solani fungal supernatant for the synthesis of CeO2 nanoparticles was studied by Fourier transform infrared (FTIR) spectroscopy. The room temperature photoluminescence spectrum of calcined CeO2 nanopowder was recorded. Field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDAX) ascertained the formation of homogeneously distributed spherically shaped CeO2 nanoparticles. Furthermore, transmission electron microscopy (TEM) demonstrated the spherical morphology of the CeO2 nanoparticles having sizes ranging from 20 to 30 nm and also the selected area electron diffraction (SAED) pattern revealed the polycrystalline nature of the CeO2 nanoparticles, which is consistent with the XRD results. The presence of surface oxidation states Ce (3d) and O (1s) of the CeO2 nanoparticles was confirmed by X-ray Phoelectron Spectroscopy (XPS) analysis. The antibacterial activity of CeO2 nanoparticles was evaluated by the disc diffusion method and it showed the highest activity against P. aeruginosa as well as K. pneumoniae. In addition, the inhibition on biofilm formation by CeO2 nanoparticles has also been examined by confocal laser scanning microscopy (CLSM). Furthermore, the electrochemical property of the biosynthesized CeO2 nanoparticles was studied by the cyclic voltammetry technique.

We have developed a novel approach to introduce silica-doped β-tricalcium phosphate (Si-β-TCP) on 316L SS substrates for enhanced biological properties. Doping of β-TCP with silica loadings ranging from 0 to 8 mol% was carried out using chemical precipitation method. Si-β-TCP powder was sintered at 800 °C followed by coating it on 316L SS substrate using electrophoretic deposition. The coated and uncoated samples were investigated by various characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and X-ray fluorescence spectroscopy (XRF). Biomineralization ability of the coatings was evaluated by immersing in simulated body fluid (SBF) solution for different number of days such as 7, 14, 21 and 28 days. The results obtained in our study have shown that the apatite formation ability was high for the 8 mol% of Si-β-TCP. This will promote better biomineralization ability compared to the other coatings.

Carbon supports are functionalized with −COOH, −OH, −NH2, surfactants, and polyelectrolytes to efficiently attach and disperse metal nanoparticles on their surface influencing the catalytic activity of fuel cell electrocatalysts. This chapter discusses different methods which have been applied for carbon support surface modifications, from chemical covalent to physical non-covalent functionalization. In the covalent method, different oxidizing agents and nitrogen-containing precursors are commonly used to anchor functional groups on carbon surface. On the other hand, in the non-covalent functionalization method different surfactants and polyelectrolytes act as capping agents and anchoring sites to help disperse and attach metal nanoparticles. With the help of surface functionalization, both electrocatalyst and fuel cell performance are improved.

International audience; Nickel doped zinc oxide (Ni/ZnO) nanostructures have the potential to improve the performance of electrochemical capacitors. This study investigates the preparation of Ni/ZnO nanomaterials by facile co-precipitation (CPM) and hydrothermal (HTM) methods. The effect of the synthesis methods on the optical, structural, chemical and morphological properties on ZnO products is investigated using ultra violet (UV)-visible spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray spectrometry (EDX), room temperature photoluminescence (PL), Fourier transform infrared (FTIR) and Raman spectroscopy. Finally, the electrochemical performance of the synthesized nanorods were examined by fabrication of a supercapacitor using standard three electrode cell configuration and tested with a cyclic voltammogram (CV) and galvanostatic charge-discharge (GCD) measurements. The results shown that the samples synthesized by HTM exhibited improved electrochemical capacitance performance with higher current density. The discharge curves are linear in the total range of potential with constant slopes, showing perfect capacitance. In conclusion, Ni/ZnO nanoparticles synthesized by this method with further optimization have the potential to lead to a high-efficiency supercapacitors.

Chitosan and silver functionalized free standing reduced graphene oxide (rGO) films were prepared using simple soak and dry strategy. Redistribution of silver aggregates on chitosan functionalized rGO films were observed by thermally annealing these films at 450 °C, in an inert atmosphere. The re-organization / redistribution of silver aggregates in the rGO films were studied using in-situ Raman scattering signals. The redistribution of silver particles occurs through melting of micron sized silver aggregates during annealing. The rearrangement of the micro-sized silver aggregates to spherical silver nanoparticle on chitosan functionalized rGO film, as a result of temperature was assisted through factors such as graphene surface ripple rearrangement and the denaturation of rGO surface interacting chitosan chains. These free-standing films with redistributed silver nanoparticles showed excellent surface enhanced Raman scattering (SERS) effect with enhanced Raman signals for folic acid sensing, showcasing its potentiality to be utilized as flexible SERS based sensors.

In this work, we report the influence of silver nanoparticles of different size on the optical behavior of the europium-doped hydroxyapatite nanorods. The presence of ionic, plasmonically visible and silent (ultra-small) silver nanoparticles on the surface of europium-doped apatite and its influence on its luminescent behavior were discussed. It was found that ionic silver exhibited a concentration-dependent enhancement in emission at the excitation of europium. For plasmonically visible and silent silver nanoparticles, the emission observed was due to the contribution of the ligand passivating the europium-doped hydroxyapatite nanoparticle surface. These nanoparticles due to its luminescent and biocompatible nature can be used for bioimaging applications.

Europium doped hydroxyapatite (EDA) nanorods with linoleic acid passivated silver ions on their surfaces were synthesized using facile, one-step hydrothermal route. Annealing the samples at 250 °C resulted in formation of ultra-small silver (USS) nanoparticles on the surface by nucleation through diffusion process. EDA exhibited luminescence properties due to the presence of europium ions doped on the calcium sites of hydroxyapatite. These EDA nanorods exhibited a different luminescent behavior in the presence of silver ions and USS nanoparticles. This report also demonstrates excellent biocompatibility and cytotoxicity of EDA nanorods with silver ions towards fibroblast cell lines (F929) and breast cancer cells (MCF-7). Visible and near infra-red (NIR) emissions in EDA, induced by silver ions and USS nanoparticles makes it a potential system for deep tissue imaging applications. The arrangement of USS over the EDA was tunable and hence the selectivity and enhancement of the Eu3+ ions emission can also be tuned. The multifunctional properties of this system such as its active luminescence over a wide range, its cell proliferation towards normal cells and cytotoxicity towards cancer cells shows its potential for application in cancer theranostics.

Nano gold / α-amylase colloidal dispersions of profound stability were made using simple procedure with a conventional reducing agent. The surface plasmon resonance of the gold nanocrystals was used to quantify the extent of the dispersion stability and functionalization. It is found that the reduced gold nanoparticles were trapped into the protein network without denaturation the structure of α-amylase protein. This kind of entrapment of particles into the protein network prevents clustering of individual gold nanoparticles (6.42 nm ± 0.92 nm) by acting as a natural spacer. Systematic entrapment was facilitated by the affinity of gold to the sulfur moieties (Au-S) in the protein structure.