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Thin film consisting of hierarchical cadmium oxide nanonecklaces has been synthesized through room temperature chemically deposited cadmium hydroxide nanowires as template followed by air annealing. Formation of thin film has been confirmed with aid of structural, surface morphological, valence state and optical, studies performed by X-ray diffraction, Raman analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–visible spectroscopy. Air annealing at 330 °C has enhanced the photo electrochemical power conversion efficiency of the CdO as photoanode to 0.21% configured through platinum as counter electrode and polyiodide as a liquid electrolyte. Complete device performance have been correlated through rate of recombination, and electron life time. The schematic energy band alignment also has been comprehended herein.

The fiber wrapped tuberose structured Fe:Sr(OH)2 have been successfully deposited by using a simple and low cost chemical approach of successive ion layer adsorption and reaction (SILAR) method as binder-free electrodes for supercapacitors. The structural properties have been obtained by the XRD patterns, while FTIR shows the chemical bond analysis. The FE-SEM micrographs show fiber wrapped tuberose structured morphology and the Fe doping into Sr(OH)2 is confirmed by EDX. The deposited films show the battery type electrode behaviour in 1 M Na2SO4 aqueous solution. As an active electrode material, the specific capacity of 871 C g−1 (specific capacitance of 792 F g−1) at 1.2 mA cm−2 with cycle retention of ∼79% at 5 mA cm−2 has been obtained for 0.5 at.% Fe:Sr(OH)2. The electrochemical properties of the synthesised electrode reveal that it has the great potential for next-generation energy storage applications.

Silver (Ag) nanoparticles were synthesized through an electroless deposition providing high surface coverage of porous material. The structural and morphological characteristics were investigated along with electrochemical studies to evaluate the charge storage performance. The nanoparticle morphology provides more active sites and diffusion paths for the electrolyte ions resulting in maximum utilization of active electrode material. Ag nanoparticles based electrode not only exhibited a maximum specific capacitance of 452 F/g (at scan rate of 2 mV/s) and specific energy of 27.8 Wh/kg, but also achieved a tremendous gain over cyclic stability by retrieving 63% capacitance after 10,000 cycles. Such attractive electrochemical behavior of the formed electrode is suitable for the manufacturing of the good quality supercapacitors by utilizing a roll-to-roll industrial production technology.

Surface coating of CdS nanoparticles over the ZnO nanorods have been performed by using simple successive ionic layer adsorption and reaction at room temperature. Initially, the seed/compact ZnO layer have been deposited via SILAR (successive ionic layer adsorption and reaction) on to fluorine doped tin oxide coated glass (FTO) substrate followed by synthesis of ZnO nanorods by chemical bath deposition method. The synthesized nano heterostructure was characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX) and high resolution-transmission electron microscopy (HR-TEM) techniques. The photovoltaic performance of the cell was recorded with a conversion efficiency of 0.123% under 100 mW/cm 2 simulated sunlight at AM 1.5G conditions.

A bottom-up approach is demonstrated for the synthesis of cadmium sulfide (CdS) nanowires on pregrown compact CdS layer through simple and low cost wet chemical approach. These CdS nanowires are loaded with Ru-metal free organic dyes namely, Rhodamine B and Rose Bengal to serve as a photoanode in dye sensitized solar cells. The dye loaded CdS NWs films revealed good absorption coverage in the visible region of the solar spectrum. The photovoltaic performance of the devices with CdS nanowires shows efficiency of 0.1201% ± 6.6 × 10 −5 % for Rhodamine B and 0.125% ± 3.4 × 10 −5 % for Rose Bengal dye under standard illumination of sunlight (AM 1.5 G, 100 mW/cm 2 ). The use of 1-D CdS nanowire proves well directed electron pathway which may exhibit promising candidate towards the next generation colourful solar cell.

Nanoheterojunctions between p-PEDOT:PSS and n-CdS were fabricated by using simple chemical method at room temperature (27 °C) on fluorine doped tin oxide (FTO) coated glass substrate. The thin layer of commercially available poly (3, 4-ethylenedioxythiophene: poly (styrene sulfonic acid)) (PEDOT:PSS) shell was formed on CdS nanowires by dip-coating method. This formed nanoheterojunction was used as liquefied petroleum gas (LPG) sensor at room temperature. The formed nanoheterojunction network with porous and high surface area enables enough space to adsorb and de-adsorb gas molecules easily and showed the gas response of 58.9% under the exposure of LPG (900 ppm). The results demonstrate that the shell configuration of p-PEDOT:PSS on n-CdS nanowires to form nanoheterojunction which provides a facile and compatible frame for the potential applications as a LPG sensors which can operate at room temperature.

In the present investigation, we report the reproducible simple solution chemistry towards synthesis of ZnO nanostructure on fluorine doped tin oxide (FTO) coated glass substrate in aqueous medium at low temperature (>100 °C). The different preparative parameters such as deposition time, bath temperature, concentration of precursor solution, pH of the bath etc. were optimized to get fibrous nanoflakes, nanobeads, nanoparticles, cactus and highly crystalline 1D nanoneedles & hexagonal nanorods of ZnO. However, the as-deposited film consists of mixture of zinc hydroxide [Zn(OH)2] and ZnO. In the present work, to get pure ZnO phase, the as-deposited films were air annealed at relatively lower temperature (200 °C). The annealed ZnO films deposited by CBD and SILAR were characterized for structural, surface morphological, optical properties and surface wettability studies etc. The simplicity of the synthesis route coupled with the variety of ZnO nanostructures is manifest to be an important candidate for nanoscale devices.

Investigation towards the performance of room temperature (27 °C) liquefied petroleum gas (LPG) sensor based on the heterojunction between p-PEDOT:PSS and n-type ZnO is reported. The junction was developed by using chemically deposited ZnO film on to fluorine doped tin oxide (FTO) coated glass substrate followed by coating of thin slurry layer of PEDOT:PSS by using spin coating technique. Both these methods are simple, inexpensive and suitable for large area applications. Different characterization techniques were used to characterize structural, surface morphological and compositional of the material deposited. LPG sensing behavior of the heterojunction was studied at room temperature along with the stability studies. At room temperature, the heterojunction showed 58.8% sensitivity upon exposure to 1000 ppm of LPG with good response and recovery time like 225 s and 190 s, respectively. Furthermore, the LPG sensor reported is cost-effective, user friendly, and easy to fabricate using low cost chemical methods at room temperature.

Cost effective, ruthenium metal free rhodamine B dye has been chemically adsorbed on ZnO films consisting of nanobeads to serve as a photo anode in dye sensitized solar cells. These ZnO films were chemically synthesized at room temperature (27 °C) on to fluorine doped tin oxide (FTO) coated glass substrates followed by annealing at 200 °C. These films consisting of inter connected nanobeads (20–40 nm) which are due to the agglomeration of very small size particles (3–5 nm) leading to high surface area. The film shows wurtzite structure having high crystallinity with optical direct band gap of 3.3 eV. Optical absorbance measurements for rhodamine B dye covered ZnO film revealed the good coverage in the visible region (460–590 nm) of the solar spectrum. With poly-iodide liquid as an electrolyte, device exhibits photon to electric energy conversion efficiency ( η ) of 1.26% under AM 1.5G illumination at 100 mW/cm 2 .

The sacrificial template free chemical synthesis of PbSe nanotubes at room temperature has been performed by lead hydroxination from cadmium hydroxide nanowires. This process was based on the ion exchange reaction to replace Cd 2+ with Pb 2+ ions from hydroxyl group followed by replacement of hydroxyl group with selenium ions. The reaction kinetics was accomplished due to more negative free energy of formation and thus the difference in the solubility products. The formed nanotubes were inclusive of Pb and Se with proper inter-chemical bonds with preferred orientations having diameter in tens of nanometer. These nanotubes can have future applications in electronic, optoelectronics and photovoltaic's as well.

Nanocrystalline cuprous oxide (Cu 2 O) thin films were synthesized on amorphous glass substrate by using simple room temperature chemical route namely, chemical bath deposition (CBD) method. The deposition kinetics played important role to get good quality nanocrystalline films with uniform thickness. The structural, surface morphological, optical and electrical properties of the films were investigated. Crystallization and growth processes obtained micro-spherical shaped grains of Cu 2 O due to agglomeration of smaller nanoparticles. An optical and electrical characterization was performed to study the optical band gap and type of electrical conductivity of the film.

The growth of AgI (silver iodide) thin films has been performed in aqueous medium using simple chemical method at room temperature (25 °C). Silver nitrate and potassium iodide have been used as source materials. Thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), surface photovoltage (SPV) and optical absorption spectroscopy. Glass and indium doped tin oxide (ITO) coated glass was used as substrates. The thin films were surface homogeneous with mixed β and γ-phases with surface roughness value of 21 nm. Optical transmission on glass exceeds 80% for 150 nm thick film with the direct band gap value of 2.85 eV. The change in crystal phases after transition temperature is studied by SPV measurements.