Bio: Manish Srivastava is an academic researcher from Indian Institute of Technology (BHU) Varanasi. The author has contributed to research in topics: Cellulase & Fourier transform infrared spectroscopy. The author has an hindex of 32, co-authored 75 publications receiving 2546 citations. Previous affiliations of Manish Srivastava include Gautam Buddha University & University of Delhi.
TL;DR: In this paper, Ceria (CeO2) nanoparticles were grown on reduced graphene oxide (RGO) via the in situ reduction of graphene oxide in the presence of cerium nitrate and CTAB, followed by a one-step hydrothermal treatment.
Abstract: Ceria (CeO2) nanoparticles were grown on reduced graphene oxide (RGO) via the in situ reduction of graphene oxide (GO) in the presence of cerium nitrate and CTAB, followed by a one step hydrothermal treatment. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy (RS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the samples. The characterization suggests that the ammonia-assisted hydrothermal method is a facile and advantageous route to synthesize CeO2–RGO nanocomposites compared to the widely used method utilising hydrazine hydrate as the reducing reagent. TEM investigations revealed that the CeO2 nanoparticles with an average size of ∼14 nm were dispersed on the layers of RGO. The catalytic activity of the CeO2–RGO nanocomposites towards the electrooxidation of hydrazine was further investigated by cyclic voltammetry measurements. The results obtained suggest that compared to bare CeO2 nanoparticles, the CeO2–RGO nanocomposite exhibits remarkably enhanced electrocatalytic activity, due to the synergistic effects between the CeO2 nanoparticles and RGO.
TL;DR: In this article, the authors reported the synthesis of nickel ferrite (NiFe 2 O 4 ) nanoparticles using sol-gel and hydrothermal methods using glycolic acid as a chelating agent.
Abstract: In the present article, we report the synthesis of Nickel ferrite (NiFe 2 O 4 ) nanoparticles using sol–gel and hydrothermal methods. In the sol–gel synthesis process we used glycolic acid as a chelating agent for the preparation of NiFe 2 O 4 nanoparticles. In this process, glycolic acid acts as a fuel which decomposes the metal complexes at low temperature and yields impurity free NiFe 2 O 4 nanocrystalline structures. In the hydrothermal process the NiFe 2 O 4 nanoparticles were synthesized at low temperature (∼160 °C). The size of NiFe 2 O 4 nanoparticles obtained through hydrothermal process was smaller (∼9 nm) than that of sol–gel process (∼27 nm). The synthesized nanoparticles were characterized by thermogravemetric analysis (TGA)/differential scanning calorimetery (DSC), Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy and vibrating sample magnetometer (VSM). The magnetic measurements of nanoparticles were done at room temperature and found that NiFe 2 O 4 nanoparticles synthesized by sol–gel method exhibit a ferromagnetic behavior with a saturation magnetization 31 emu g −1 while the NiFe 2 O 4 nanoparticles synthesized by hydrothermal process exhibit a superparamagnetic behavior with a saturation magnetization of 46 emu g −1 .
TL;DR: This review highlights the recent progress in graphene and graphene-based metal-oxide hybrids for use as electrode materials in LIBs and emphasis has been placed on the synthesis methods, structural properties, and synergetic effects ofMetal-oxide/graphene hybrids towards producing enhanced electrochemical response.
Abstract: Today, one of the major challenges is to provide green and powerful energy sources for a cleaner environment. Rechargeable lithium-ion batteries (LIBs) are promising candidates for energy storage devices, and have attracted considerable attention due to their high energy density, rapid response, and relatively low self-discharge rate. The performance of LIBs greatly depends on the electrode materials; therefore, attention has been focused on designing a variety of electrode materials. Graphene is a two-dimensional carbon nanostructure, which has a high specific surface area and high electrical conductivity. Thus, various studies have been performed to design graphene-based electrode materials by exploiting these properties. Metal-oxide nanoparticles anchored on graphene surfaces in a hybrid form have been used to increase the efficiency of electrode materials. This review highlights the recent progress in graphene and graphene-based metal-oxide hybrids for use as electrode materials in LIBs. In particular, emphasis has been placed on the synthesis methods, structural properties, and synergetic effects of metal-oxide/graphene hybrids towards producing enhanced electrochemical response. The use of hybrid materials has shown significant improvement in the performance of electrodes.
TL;DR: This review deals with four different types of carbon allotrope including carbon nanotubes, graphene, fullerenes and nanodiamonds and summarizes the results of recent studies that are likely to have implications in cancer theranostics.
Abstract: One of the major challenges in our contemporary society is to facilitate healthy life for all human beings. In this context, cancer has become one of the most deadly diseases around the world, and despite many advances in theranostics techniques the treatment of cancer still remains an important problem. With recent advances made in the field of nano-biotechnology, carbon-based nanostructured materials have drawn special attention because of their unique physicochemical properties, giving rise to great potential for the diagnosis and therapy of cancer. This review deals with four different types of carbon allotrope including carbon nanotubes, graphene, fullerenes and nanodiamonds and summarizes the results of recent studies that are likely to have implications in cancer theranostics. We discuss the applications of these carbon allotropes for cancer imaging and drug delivery, hyperthermia, photodynamic therapy and acoustic wave assisted theranostics. We focus on the results of different studies conducted on functionalized/conjugated carbon nanotubes, graphene, fullerenes and nanodiamond based nanostructured materials reported in the literature in the current decade. The emphasis has been placed on the synthesis strategies, structural design, properties and possible mechanisms that are perhaps responsible for their improved theranostic characteristics. Finally, we discuss the critical issues that may accelerate the development of carbon-based nanostructured materials for application in cancer theranostics.
TL;DR: The present review provides an overview of the cost-effective and present scenario of cellulase production in the biofuel industries including recent advancements.
Abstract: Nonrenewable fossil fuels and their serious environmental impact have forced to develop renewable & sustainable energy sources. In this scenario, cellulases have found extensive applications in the biofuel industries. Three main components of the cellulase enzymatic system, namely endoglucanase, exoglucanase and β-glycosidase, effectively convert cellulosic substrates into fermentable sugars. The commercial production of cellulase is currently performed under submerged fermentation (SmF) conditions using mesophilic microbial strains which are non-economic and also non-sustainable. Although, production of fungal cellulases using solid-state fermentation (SSF) is economically advantageous and a preferable route for industrial purposes, it suffers from a few bottlenecks ( e.g. scale-up, difficult to control process parameters). Therefore, the present review provides an overview of the cost-effective and present scenario of cellulase production in the biofuel industries including recent advancements. In addition, the current limitations hampering the cost-effective production of cellulase have also been discussed to resolve them in the near future.
TL;DR: It is believed that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve the ability to combat cancers.
Abstract: The nonradiative conversion of light energy into heat (photothermal therapy, PTT) or sound energy (photoacoustic imaging, PAI) has been intensively investigated for the treatment and diagnosis of cancer, respectively. By taking advantage of nanocarriers, both imaging and therapeutic functions together with enhanced tumour accumulation have been thoroughly studied to improve the pre-clinical efficiency of PAI and PTT. In this review, we first summarize the development of inorganic and organic nano photothermal transduction agents (PTAs) and strategies for improving the PTT outcomes, including applying appropriate laser dosage, guiding the treatment via imaging techniques, developing PTAs with absorption in the second NIR window, increasing photothermal conversion efficiency (PCE), and also increasing the accumulation of PTAs in tumours. Second, we introduce the advantages of combining PTT with other therapies in cancer treatment. Third, the emerging applications of PAI in cancer-related research are exemplified. Finally, the perspectives and challenges of PTT and PAI for combating cancer, especially regarding their clinical translation, are discussed. We believe that PTT and PAI having noteworthy features would become promising next-generation non-invasive cancer theranostic techniques and improve our ability to combat cancers.
TL;DR: The two-step solution-phase reactions to form hybrid materials of Mn(3)O(4) nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications should offer a new technique for the design and synthesis of battery electrodes based on highly insulating materials.
Abstract: We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.
TL;DR: New advances in electrochemical sensors and biosensors based on nanomaterials and nanostructures during 2013 to 2014 are focused on to provide the reader with a clear and concise view of new advances in areas ranging from electrode engineering, strategies for electrochemical signal amplification, and novel electroanalytical techniques used in the miniaturization and integration of the sensors.
Abstract: Taking advantage of exceptional attributes, such as being easy-to-operate, economical, sensitive, portable, and simple-to-construct, in recent decades, considerable attention has been devoted to the integration of recognition elements with electronic elements to develop electrochemical sensors and biosensors.Various electrochemical devices, such as amperometric sensors, electrochemical impedance sensors, and electrochemical luminescence sensors as well as photoelectrochemical sensors, provide wide applications in the detection of chemical and biological targets in terms of electrochemical change of electrode interfaces. With remarkable achievements in nanotechnology and nanoscience, nanomaterial-based electrochemical signal amplifications have great potential of improving both sensitivity and selectivity for electrochemical sensors and biosensors. First of all, it is well-known that the electrode materials play a critical role in the construction of high-performance electrochemical sensing platforms for detecting target molecules through various analytical principles. Furthermore, in addition to electrode materials, functional nanomaterials can not only produce a synergic effect among catalytic activity, conductivity, and biocompatibility to accelerate the signal transduction but also amplify biorecognition events with specifically designed signal tags, leading to highly sensitive biosensing. Significantly, extensive research on the construction of functional electrode materials, coupled with numerous electrochemical methods, is advancing the wide application of electrochemical devices. For example, Walcarius et al. highlighted the recent advances of nano-objects and nanoengineered and/or nanostructured materials for the rational design of biofunctionalized electrodes and related (bio)sensing systems.1 The attractiveness of such nanomaterials relies on their ability to act as effective immobilization matrices and their intrinsic and unique features as described above. These features combined with the functioning of biomolecules contribute to the improvement of bioelectrode performance in terms of sensitivity and specificity. Our group recently presented a general overview of nanomaterial-enhanced paper-based biosensors including lateral-flow test-strip and paper microfluidic devices.2 With different kinds of nanoparticles (NPs), paper-based biosensor devices have shown a great potential in the enhancement of sensitivity and specificity of disease diagnosis in developing countries. This Review focuses on recent advances in electrochemical sensors and biosensors based on nanomaterials and nanostructures during 2013 to 2014. The aim of this effort is to provide the reader with a clear and concise view of new advances in areas ranging from electrode engineering, strategies for electrochemical signal amplification, and novel electroanalytical techniques used in the miniaturization and integration of the sensors. Moreover, the authors have attempted to highlight areas of the latest and significant development of enhanced electrochemical nanosensors and nanobiosensors that inspire broader interests across various disciplines. Electrochemical sensors for small molecules, enzyme-based biosensors, genosensors, immunosensors, and cytosensors are reviewed herein (Figure (Figure1).1). Such novel advances are important for the development of electrochemical sensors that open up new avenues and methods for future research. We recommend readers interested in the general principles of electrochemical sensors and electrochemical methods to refer to other excellent literature for a broad scope in this area.3,4 However, due to the explosion of publications in this active field, we do not claim that this Review includes all of the published works in the past two years and we apologize to the authors of excellent work, which is unintentionally left out. Figure 1 Schematic illustration of electrochemical sensors and biosensors based on nanomaterials and nanostructures, in which electrochemical sensors for small molecular, enzyme-based biosensors, genosensors, immunosensors, and cytosensors are demonstrated.
TL;DR: The physicochemical characteristics of spinels such as their compositions, structures, morphologies, defects, and substrates have been rationally regulated through various approaches and can yield spinels with improved ORR/OER catalytic activities, which can further accelerate the speed, prolong the life, and narrow the polarization of fuel cells, metal-air batteries, and water splitting devices.
Abstract: Spinels with the formula of AB2O4 (where A and B are metal ions) and the properties of magnetism, optics, electricity, and catalysis have taken significant roles in applications of data storage, biotechnology, electronics, laser, sensor, conversion reaction, and energy storage/conversion, which largely depend on their precise structures and compositions. In this review, various spinels with controlled preparations and their applications in oxygen reduction/evolution reaction (ORR/OER) and beyond are summarized. First, the composition and structure of spinels are introduced. Then, recent advances in the preparation of spinels with solid-, solution-, and vapor-phase methods are summarized, and new methods are particularly highlighted. The physicochemical characteristics of spinels such as their compositions, structures, morphologies, defects, and substrates have been rationally regulated through various approaches. This regulation can yield spinels with improved ORR/OER catalytic activities, which can furth...
TL;DR: In this article, the authors summarized previous and most recent theoretical predictions and experimental outcomes in the field of oxide-based catalysts for the oxygen evolution reaction (OER), both operating in acidic and alkaline environments.
Abstract: The growing need to store large amounts of energy produced from renewable sources has recently directed substantial R&D efforts towards water electrolysis technologies. Although the description of the electrochemical reaction of water electrolysis dates back to the late 18th century, improvements in terms of efficiency and stability are foreseen for a widespread market penetration of water electrolysers. Particular advances are required for the electrode materials catalysing the oxygen evolution reaction (OER) at the anode side, which has slow kinetics and thus is one of the major sources of the cell efficiency loss. In recent years, high-level theoretical tools and computational studies have led to significant progress in the atomic-level understanding of the OER and electrocatalyst behaviour. In parallel, several experimental studies have explored new catalytic materials with advanced properties and kinetics on a technical relevant level. This contribution summarises previous and the most recent theoretical predictions and experimental outcomes in the field of oxide-based catalysts for the OER, both operating in acidic and alkaline environments.