The realization of efficient and durable catalyst-based energy harvesting devices by integrating low-cost materials with low-temperature techniques has recently received great attention. In this direction, we developed synergistic Oxygen evolution reaction (OER) catalysts by combining low-cost surface passivated or functionalized ZnO nanorods (F. ZnO NRs) structures with stainless-steel mesh (SSM/F. ZnO NRs) as three-dimensional (3D) structures and demonstrated excellent water-splitting characteristics. Here, SSM/ZnO nanorods structures were initially passivated by electrochemical deposition of ultrathin cobalt oxide (Co3O4) layers and analyzed with advanced analytical techniques even before and after OER catalysis. As individual materials, either stainless-steel or Co3O4 deposited ZnO nanostructures possess very low catalytic activity, whereas their integrated 3D structures showed unusual catalytic performance as OER anodes. As compared to SSM and SSM/ZnO structures, Co3O4 passivated SSM/ZnO structures exhibit very low overpotential (-290 V for the current density of 10 mA/cm2) with a reduced Tafel slope of 59 mV/dec along with excellent cycling stability and durability even for longtime energy productions. The establishment of large surface-area and fine energy band alignments along with favorable interfaces formed between SSM, ZnO@Co3O4, and electrolyte||Pt structures, presence of Co3O4 as a passive cum protective layer, and synergistic effects play significant roles in the predominantly enhanced catalytic activity of SSM/F. ZnO electrodes.

The adoption of nanostructured metal-oxides integrated graphene monolayers-based heterostructures appears to be a promising approach for enhancing the performance of various devices. However, precisely controlled growth of such unique heterostructures without disturbing the monolayer graphene characteristics remains a challenging task especially over a large area with good uniformity. Herein, ultrathin metal-oxide (p-Co3O4 and nZnO) nanostructures (MONSs) integrated graphene monolayer (GML) heterostructures are carefully developed by fascinating the graphene native defects while nucleation and growth of MONSs. Metal-oxides integrated graphene monolayers with lower material densities (<= 30 mu g/cm(2)) significantly enhanced the quality (2D/G-5-9) and reduced the electrical resistance (11-17 omega/sq.) of graphene layers, whereas the heterostructures developed with higher densities possess predominant water-oxidation characteristics than that of their individual components. Further, the Co3O4/GML heterostructures-based micro-supercapacitors, fabricated over 25 mu m polyimide sheets, showed excellent mechanical stability and flexibility with a volumetric and specific capacitance of 7.76 F/cm(3) and 1.27 F/g, respectively. The ZnO/GML heterostructures designed over micron thick parylene film displayed exciting photoresistor characteristics with photosensitivity of similar to 1.54 and superb flexibility and skin-mountability. Synergistic multifunctional characteristics of these ultrathin heterostructures offer the possibility to realize various eco-friendly ultrathin as well as skin-mountable energy and health monitoring devices.

Development of two-dimensional high-quality graphene monolayers has recently received great concern owing to their enormous applications in diverging fields including electronics, photonics, composite materials, paints and coatings, energy harvesting and storage, sensors and metrology, and biotechnology. As a result, various groups have successfully developed graphene layers on different substrates by using the chemical vapor deposition method and explored their physical properties. In this direction, we have focused on the state-of-the-art developments in the growth of graphene layers, and their functional applications in biotechnology. The review starts with the introduction, which contains outlines about the graphene and their basic characteristics. A brief history and inherent applications of graphene layers followed by recent developments in growth and properties are described. Then, the application of graphene layers in biodevices is reviewed. Finally, the review is summarized with perspectives and future challenges along with the scope for future technological applications.

The article reports a novel and highly efficient methodology for the development of surface defects-free zinc oxide (ZnO) nanostructures, which are highly useful for various opto-electronic and electronic devices. Using this approach, we have developed high-quality ZnO nanostructures with comparable physical and chemical properties to hightemperature grown ones. Initially, ZnO nanostructures were developed by low-temperature chemical bath deposition, and the surface defects passivated structures were obtained by atomic layer deposition of homo-molecular clusters, i.e., Zn and O atomic layers. The surface passivated ZnO nanostructures exhibited excellent chemical stoichiometry between their constituents with enhanced crystalline quality. These nanostructures also showed improved light transmittance in the wavelengths range of 450-1000 nm, and light emission in the ultraviolet region. Further, the surface passivated nanostructures exhibited remarkable device performance as photoanodes with a greatly improved photocurrent density, more than 3 times, and reduced cathodic current of 6.17 x 10(-7) A@-0.4 V. Significantly, the light-to-dark current ratio of the PEC devices fabricated with passivated ZnO nanostructures is found to be 1761. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The invention of graphene, as a two-dimensional (2D) atomic layered material, has created enormous scientific revolutions in materials science. As a result, there are a variety of 2D materials came into limelight and intervening the existing technology. Today, one of the focusing issues in graphene technology is the development of functionalized (doped) graphene monolayers since the pristine graphene is chemically inert, hydrophobic and zero band gap material. As a result, the potential applications of graphene are limited to a few fields of science and technology. Surface functionalization, one of the typical approaches, is well-adopted for the development of functionalized graphene layers. In this scenario, we reviewed the latest advancements exclusively in the development of functionalized graphene layers, and exciting breakthroughs in graphene's science and technology. A brief history along with intrinsic properties of graphene is discussed in the introduction. Then, the methods adopted for the realization of functionalized graphene layers, and the impact of surface modification on their physical and chemical properties along with device performances are elaborately discussed. Finally, the review is summarized and outlined the perspectives of functionalized graphene layers in view of the development of multifunctional high-quality graphene layers for next-generation device applications.

Amorphous cobalt oxide (CoO) encapsulated zinc oxide (ZnO) nanostructures were developed by adopting three low-temperature methods respectively atomic layer deposition, chemical bath deposition, and electrochemical deposition. The impact of CoO growth on the physical and chemical properties of ZnO nanostructures was investigated. Then, the ZnO/CoO core/shell nanostructures grown under optimized conditions were adopted for the fabrication of photoelectrochemical (PEC) water-splitting devices. The catalytic performance of ZnO nanostructures is substantially improved after their encapsulation with CoO layers. In addition, the chemical stability and durability of the structures are significantly enhanced. Under typical measurement conditions, these surface-modified ZnO nanostructures exhibited incident photon to charge carrier conversion efficiency (IPCE) higher than 16%, and a stable photocurrent density of 1.25 mA cm-2. Further, these ZnO/CoO nanostructured photoanodes showed a high illumination to dark current density ratio, ~2910.

Tin (II) sulfide (SnS), one of the most abundant materials, is being considered as an absorber material for the development of low-cost and nontoxic solar cell devices. In this direction, we have developed nanocrystalline films of SnS with uniform morphology on different substrates by adopting two-step thermal evaporation process. The surface studies show that irrespective of substrate nature, the as-grown SnS films possess uniform surface-morphology with well-defined facets. Structural studies reveal that SnS films grown on various substrates possess an orthorhombic crystal structure. However, as compared to other substrates, the structures developed on sapphire and copper exhibit 〈010〉 as preferential growth direction. From the electrical measurements, it is noticed that the films deposited on highly-conductive substrates consist of low electrical resistance, whereas the films are slightly resistive on insulating substrates. Based on these investigations it is emphasized that high-quality SnS films can be developed with uniform morphology on any substrates by adopting our two-step process.

Eco-friendly and efficient rectifying p-n diodes have been developed by using cost-effective and non-toxic fin monosulfide (SnS) thin films. Chemically stoichiometric fin monosulfide (SnS) thin films followed by titanium/gold (Ti/Au) bilayer contacts were deposited on Si substrates and then, the structures were treated by rapid thermal annealing process (RTP) at different temperatures. The impact of RTP treatment on the surface morphology and chemical composition of Ti/Au contacts and SnS films along with their electrical characteristics were investigated. The electrical measurements show that as compared to untreated Si/SnS/Ti/Au structures, the heat-treated structures typically at 200 degrees C possess low electrical resistivity and contact resistance of similar to 3 x 10(-2) Omega cm and similar to 11 k Omega, respectively. Heterojunction formed between p-SnS and n-Si exhibited excellent diode characteristics and possess a high current flow in the order of milliamperes, and excellent rectification factor of 1177@ 5 V.

Chemically stoichiometric and electrically low-resistive high-quality zinc oxide (ZnO) nanostructures have been developed by surface passivation with atomic layer deposited ZnO layers. The impacts of homogeneous ZnO layer growth and its thickness on the physical properties ZnO nanorods were investigated. Vertically aligned ZnO nanorod structures were synthesized by two-step process, and the surface passivation was performed by atomic layer deposition ZnO at low temperatures. Surface passivated ZnO nanorods exhibit excellent improvement in crystallinity, chemical stoichiometry, optical, and electrical properties. Further, the surface passivated structures show significant enhancement in water-oxidation performance (nearly 3 orders of magnitude, i.e., mu A -> mA) with greatly reduced overpotentials. These investigations emphasize that surface passivation of hydrothermally grown ZnO nanostructures with the homogeneous materials can significantly enhance the structural and optical quality along with their device performance.

We have developed thin zinc oxide (ZnO) layers protected highly conductive p-type silicon (Si) electrodes and investigated their diode and photoanode characteristics. ZnO layers have been deposited on the glass as well as p-Si substrates at a temperature of 400 degrees C by pulsed spray pyrolysis method. The crystal structure, surface morphology, and phase purity of the layers along with electrical characteristics of the heterostructures were investigated. Finally, the photocatalytic water oxidation performance of the ZnO/Si structures was studied in an alkaline electrolyte solution (pH = 10). The as-grown devices exhibited excellent diode characteristics with a turn-on voltage of 4.5 V, and applied bias-voltage dependent carrier transport mechanisms. As compared to bare Si, ZnO coated Si-based PEC devices showed good stability and durability along with very low onset potential of 0.07 V versus Ag/AgCl. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Tin (II) sulfide (SnS) thin films have been developed on highly conductive indium doped tin oxide (ITO) substrates by using thermal evaporation technique at optimized deposition conditions. Here, SnS films were deposited at a substrate temperature of 300 degrees C by maintaining 14 cm distance between source to substrates with a rate of deposition of 1-2 nms(-1) and film thickness of 500 nm. Then, the crystal structure, morphology, electrical, and optical properties along with chemical composition of SnS films have been investigated and discussed in view of their potential applications in photovoltaic technology. The obtained results reveal that SnS films grown on ITO substrates have (111) as preferential orientation crystals with different sizes. These films are highly rough-in surface morphology, and exhibited very low-electrical resistivity in the order of 10(-3) Omega cm. These films also exhibited direct optical band gap and transmittance of about 60%. From these investigations we emphasized that SnS films deposited on ITO substrates could be adopted as an absorber layer for the development of solar cell devices or active component for other multifunctional devices.

In this article the sustainability of ZnO nanostructures under dynamic shock waves has been investigated. ZnO nanorods were synthesized on stainless steel (SS) substrates and exposed to shock waves in an inert atmosphere. The impact of shock waves on physical properties of ZnO nanostructures was analyzed. ZnO nanostructures grown on SS substrates exhibit excellent sustainability over different shock waves generated temperatures and pressures. The crystal structure and surface morphology of shock waves treated ZnO nanorods remain the same as untreated ones and however, the chemical stoichiometry and light emission properties are significantly changed. From these investigations it is emphasized that ZnO nanostructures could be adopted for various applications in space engineering technology where the surrounding temperature and pressure is below 8000 K and 2 MPa.

This article reports the electrical characteristics of pristine, polycrystalline and single crystalline nickel (Ni) layer capped zinc oxide (ZnO) nanowires. Core/shell ZnO/Ni nanostructures were developed using chemical vapor deposition and e-beam evaporation, and the structures were annealed at different temperatures. Field effect transistor (FET) devices were fabricated using photolithography and investigated their characteristics at room temperature. All FET devices exhibited depletion-mode characteristics with n-type conductivity. However, single-crystalline Ni shelled ZnO nanowires based FET devices showed a high on/off ratio and transconductance, as compared to other devices. The overall measurements show that though the ZnO nanowires capped with Ni layer, their electrical properties remain same as pristine ZnO nanowires.

SnS based MISFET devices exhibit a high turn-on voltage of +5.13 V and rectification factor of 1383@+6 V.

SnS nanowires with high aspect-ratio were developed by chemical vapor deposition and their physical and chemical properties were explored, along with their field effect transistor characteristics.

We synthesized poly‐trimethoxyphenylsilane (PTMS) and applied it as the carrier film to CVD graphene transfer process for the first time. Since the PTMS particles are not fully crosslinked due to the presence of bulky groups, they do not have crystallinity in the long‐range order on the graphene surface and are easily removed by solvent such as toluene. Raman, AFM, and X‐ray photoemission (especially, Si 2p signal) analysis confirmed that the surface of the transferred graphene was clean without PTMS impurities.