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P. Jha

Bio: P. Jha is an academic researcher from Bhabha Atomic Research Centre. The author has contributed to research in topics: Materials science & Polypyrrole. The author has an hindex of 15, co-authored 41 publications receiving 698 citations. Previous affiliations of P. Jha include Homi Bhabha National Institute & B.P. Koirala Institute of Health Sciences.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the preparation of flexible polyaniline-silver (PANI-Ag) nanocomposite films via an in situ facile UV induced polymerization of aniline in presence of AgNO 3.

93 citations

Journal ArticleDOI
TL;DR: In this article, the anchoring mechanism of N719 dye molecules on oxalic acid treated TiO2 (OA-TiO2) electrodes has been investigated using extended X-ray absorption fine structure (EXAFS) measurements, Fourier transform infrared spectroscopy (FTIR), UV-vis and XPS.
Abstract: The anchoring mechanism of N719 dye molecules on oxalic acid treated TiO2 (OA-TiO2) electrodes has been investigated using extended X-ray absorption fine structure (EXAFS) measurements, Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). The FTIR spectroscopy of OA-TiO2 electrodes revealed that the oxalic acid dissociates at the TiO2 surface and binds through bidentate chelating and/or bidentate bridging. Analyses of EXAFS, FTIR, UV–vis, and XPS measurements of N719 dye loaded onto OA-TiO2 revealed that the binding of N719 molecules takes place via interaction between the Ru atom of the dye and O– of bidentate bridged oxalate ions at the TiO2 surface. This mechanism is quite different from the binding of N719 onto untreated TiO2 (WO-TiO2) surface, where −COOH and SCN groups of the dye directly bind to the TiO2 surface. The analyses of UV–vis data show that the amount of N719 dye loading onto OA-TiO2 surface is much higher than that onto the nati...

74 citations

Journal ArticleDOI
TL;DR: In this article, polypyrrole-silver (PPy-Ag) nanocomposite films were prepared on a N-(3-trimethoxysilylpropyl)pyrdrug modified biaxially oriented polyethylene terephthalate (BOPET) substrate by photopolymerisation of pyrrole using AgNO3 as a photo-initiator.
Abstract: Polypyrrole-silver (PPy–Ag) nanocomposite films were prepared on a N-(3-trimethoxysilylpropyl)pyrrole modified biaxially oriented polyethylene terephthalate (BOPET) substrate by photopolymerisation of pyrrole using AgNO3 as a photo-initiator. The films were prepared for a fixed molar concentration of pyrrole (0.5 M), varying molar concentrations of AgNO3 (0.05–0.7 M) and different UV exposure times (15 min–180 min). With increasing AgNO3 concentration or with increasing polymerisation time, the film morphology shows a transition from two dimensional lamellar to granular structures. The films are adherent, flexible and exhibit a maximum room temperature electrical conductivity of ∼15 S cm−1 (for AgNO3 ∼ 0.5 M, 120 min of UV exposure). However, the films directly prepared on pristine BOPET show granular morphology and their conductivity value is ∼0.5 S cm−1. The high conductivity of PPy–Ag films is attributed to the high conjugation length, the incorporation of Ag nano-particles between the polypyrrole chains and the ordered structure due to the templating effect of the silanised pyrrole layer, as confirmed by GIXRD, FTIR, Raman and temperature dependent conductivity measurements. The metallic state of the embedded Ag nano-particles in the polypyrrole matrix is confirmed by XRD and XPS. The films with the least amount of Ag (AgNO3 ∼ 0.1 M) only show a reversible conductivity change in the opposite manner on exposure to ppm levels of H2S and NH3 gases. The mechanism has been proposed to explain these antagonistic responses for reducing gases.

73 citations

Journal ArticleDOI
TL;DR: In this article, a facile route for synthesis of free standing polypyrrole-silver (PPy-Ag) nanocomposite films by photopolymerization of pyrrole using AgNO3 as photosensitizer in aqueous medium was reported.
Abstract: We report a facile route for synthesis of free standing polypyrrole–silver (PPy–Ag) nanocomposite films by photopolymerization of pyrrole using AgNO3 as photosensitizer in aqueous medium. In this process PPy–Ag films were formed at the air–water interface and at the bottom of the beaker. The films formed at the air–water interface are thin (≤2 μm), flexible, have a uniform distribution of metallic Ag nanoparticles and exhibit electrical conductivity (∼1.5 S cm−1). The thick (∼200 μm) PPy–Ag films prepared at the bottom of the beaker exhibit lower conductivity (∼0.15 S cm−1). Interestingly, the more conductive thin PPy–Ag films exhibit a low specific capacitance of 58 F g−1 as compared to the specific capacitance of 282 F g−1 for the thicker PPy–Ag films at a 1 mV s−1 scan rate in 0.5 M K2SO4 electrolyte. The better electrochemical activity and high specific capacitance of the thicker PPy–Ag films is attributed to their porous structure, which provides a larger electrolyte accessible conductive surface for redox reactions. This simple approach for the synthesis of PPy–Ag films along with their promising electrochemical properties allows their possible application as a substrate free electrode material for supercapacitors.

52 citations

Journal ArticleDOI
TL;DR: In this paper, polypyrrole-silver nanocomposite films were prepared by interfacial photopolymerization of pyrrole (in DCM) using AgNO3 (aqueous) as photosensitizer.
Abstract: Free standing polypyrrole-silver nanocomposite films were prepared by interfacial photopolymerization of pyrrole (in DCM) using AgNO3 (aqueous) as photosensitizer. During the photopolymerization process, film formation starts first at the DCM–water interface and later at the air–water interface. The films prepared at the air–water interface are thin (<1 μm), flexible, having a very low content of uniformly distributed metallic Ag nanoparticles and exhibiting high electrical conductivity ∼14.8 S cm−1. The thick films (∼200 μm) prepared at the DCM–water interface are porous, mechanically weak, contain a very high amount of Ag micro and nanoparticles and exhibit two orders of magnitude lower conductivity ∼0.1 S cm−1. High conductivity of PPy-Ag films formed at the air–water interface is attributed to controlled polymerization due to the limited availability of pyrrole and Ag+ ions at this interface.

52 citations


Cited by
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Journal ArticleDOI
TL;DR: This article panoramically reviews the counter electrodes in D SSCs, which is of great significance for enhancing the development levels of DSSCs and other photoelectrochemical devices.
Abstract: Dye-sensitized solar cells (DSSCs) are regarded as prospective solar cells for the next generation of photovoltaic technologies and have become research hotspots in the PV field. The counter electrode, as a crucial component of DSSCs, collects electrons from the external circuit and catalyzes the redox reduction in the electrolyte, which has a significant influence on the photovoltaic performance, long-term stability and cost of the devices. Solar cells, dye-sensitized solar cells, as well as the structure, principle, preparation and characterization of counter electrodes are mentioned in the introduction section. The next six sections discuss the counter electrodes based on transparency and flexibility, metals and alloys, carbon materials, conductive polymers, transition metal compounds, and hybrids, respectively. The special features and performance, advantages and disadvantages, preparation, characterization, mechanisms, important events and development histories of various counter electrodes are presented. In the eighth section, the development of counter electrodes is summarized with an outlook. This article panoramically reviews the counter electrodes in DSSCs, which is of great significance for enhancing the development levels of DSSCs and other photoelectrochemical devices.

547 citations

Journal ArticleDOI
TL;DR: The review summarizes the most significant progresses related to room temperature gas sensing by using hierarchical oxide nanostructures, graphene and its derivatives and 2D transition metal dichalcogenides, highlighting the peculiar gas sensing behavior with enhanced selectivity, sensitivity and long-term stability.
Abstract: Room-temperature (RT) gas sensing is desirable for battery-powered or self-powered instrumentation that can monitor emissions associated with pollution and industrial processes. This review (with 171 references) discusses recent advances in three types of porous nanostructures that have shown remarkable potential for RT gas sensing. The first group comprises hierarchical oxide nanostructures (mainly oxides of Sn, Ni, Zn, W, In, La, Fe, Co). The second group comprises graphene and its derivatives (graphene, graphene oxides, reduced graphene oxides, and their composites with metal oxides and noble metals). The third group comprises 2D transition metal dichalcogenides (mainly sulfides of Mo, W, Sn, Ni, also in combination with metal oxides). They all have been found to enable RT sensing of gases such as NOx, NH3, H2, SO2, CO, and of vapors such as of acetone, formaldehyde or methanol. Attractive features also include high selectivity and sensitivity, long-term stability and affordable costs. Strengths and limitations of these materials are highlighted, and prospects with respect to the development of new materials to overcome existing limitations are discussed.

478 citations

Journal ArticleDOI
01 Mar 2016-Carbon
TL;DR: In this article, the influence of the intrinsic properties of these fillers (graphene and its derivatives) and their state of dispersion in polymer matrix on the gas barrier properties of graphene/PNCs is discussed.

456 citations

Posted Content
TL;DR: In this paper, the influence of the intrinsic properties of these fillers (graphene and its derivatives) and their state of dispersion in polymer matrix on the gas barrier properties of graphene/PNCs are discussed.
Abstract: Due to its exceptionally outstanding electrical, mechanical and thermal properties, graphene is being explored for a wide array of applications and has attracted enormous academic and industrial interest. Graphene and its derivatives have also been considered as promising nanoscale fillers in gas barrier application of polymer nanocomposites (PNCs). In this review, recent research and development of the utilization of graphene and its derivatives in the fabrication of nanocomposites with different polymer matrices for barrier application are explored. Most synthesis methods of graphene-based PNCs are covered, including solution and melt mixing, in situ polymerization and layer-by-layer process. Graphene layers in polymer matrix are able to produce a tortuous path which works as a barrier structure for gases. A high tortuosity leads to higher barrier properties and lower permeability of PNCs. The influence of the intrinsic properties of these fillers (graphene and its derivatives) and their state of dispersion in polymer matrix on the gas barrier properties of graphene/PNCs are discussed. Analytical modeling aspects of barrier performance of graphene/PNCs are also reviewed in detail. We also discuss and address some of the work on mixed matrix membranes for gas separation.

401 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provide a brief description of the current status of gas chemiresistive sensors based on polyaniline and highlight the properties and applications of these devices in diverse range of applications.
Abstract: This review focuses on some recent advances made in the field of gas sensors based on polyaniline [PANI], a conducting polymer with excellent electronic conductivity and electrochemical properties. Conducting polymers represent an important class of organic materials with an enhanced resistivity towards external stimuli. Among them, PANI polymers have attracted wide interest because of the versatility in their use, combined with the easy of synthesis, high yield and good environmental stability, together with a favorable response to guest molecules at room temperature. Moreover, PANI can be shaped into various structures with different morphologies and the possibility of obtaining nanofibers, in addition to thin films, has opened a rapid development of ultrasensitive chemical sensors, with improved processability and functionality. This review provides a brief description of the current status of gas chemiresistive sensors based on polyaniline and highlights the properties and applications of these devices in diverse range of applications.

334 citations