Faculty Publications
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Item Synthesis and photocatalytic properties of graphitic carbon nitride nanofibers using porous anodic alumina templates(Institute of Physics Publishing helen.craven@iop.org, 2017) Suchitra, S.M.; Udayashankar, N.K.In the present study, we describe an effective method for the synthesis of Graphitic carbon nitride (GCN) nanostructures using porous anodic alumina (AAO) membrane as template by simple thermal condensation of cyanamide. Synthesized nanostructure was fully analysed by various techniques to detect its crystalline nature, morphology, luminescent properties followed by the evaluation of its photocatalytic activity in the degradation of Methylene blue dye. Structural analysis of synthesized GCNNF was systematically carried out using x-ray powder diffraction (XRD) and scanning electron microscope (SEM), and. The results confirmed the growth of GCN inside the nanochannels of anodic alumina templates. Luminescent properties of GCNNF were studied using photoluminescence (PL) spectroscopy. PL analysis showed the presence of a strong emission peak in the wavelength range of 350-600 nm in blue region. GCNNF displays higher photocatalytic performance in the photodegradation of methylene blue compare to the bulk GCN. Highlights 1. In the present paper, we report the synthesis of graphitic carbon nitride nanofibers (GCNNF) using porous anodic aluminium oxide membranes as templates through thermal condensation of cyanamide at 500 °C. 2. The synthesis of Graphitic carbon nitride nanofibers using porous andic alumina template is the efficient approach for increasing crystallinity and surface area. 3. The high surface area of graphitic carbon nitride nanofibers has a good impact on novel optical and photocatalytic properties of the bulkGCN. 4. AAO templating of GCN is one of the versatile method to produce tailorable GCN nanostructures with higher surface area and less number of structural defects. 5. Towards photocatalytic degradation of dyes, the tuning of physical properties is very essential thing hence we are succeeded in achieving better catalytic performance of GCN nanostructures by making use of AAO templates. © 2017 IOP Publishing Ltd.Item Influence of porewidening duration on the template assisted growth of graphitic carbon nitride nanostructures(Institute of Physics Publishing helen.craven@iop.org, 2018) Suchitra, S.M.; Udayashankar, N.K.Porous anodic aluminium oxide (AAO) membranes with a highly ordered pore arrangement are typically used as ideal templates for the synthesis of numerous nanostructured materials. Highly ordered templates gained significant attraction due to the fact that they are readily fabricated through self-organised simple anodization process. In this paper, the effect of different pore-widening treatments on the quality of the pores of the AAO templates prepared with different electrolytes were inspected. Results confirmed that, without altering the interpore distance different pore dimensions and diameters of the AAO templates can be easily achieved by chemical pore widening process at room temperature. Also, graphitic carbon nitride nanorods of different dimension have been fabricated from AAO template after porewidening process. These nanostructures are widely used in case of metal free visible light driven photo catalysis, photo degradation of organic pollutants, photo electric conversion and water splitting applications. © 2018 IOP Publishing Ltd.Item Synergism of graphitic-carbon nitride and electrospinning on the physico-chemical characteristics and piezoelectric properties of flexible poly(vinylidene fluoride) based nanogenerator(Springer Netherlands rbk@louisiana.edu, 2019) Khalifa, M.; Mahendran, A.; Anandhan, S.Herein, we investigated the piezoelectric performance of electrospun poly(vinylidene fluoride)/graphitic carbon nitride (PVDF/g-C 3 N 4 ) nanocomposite fibers (PGN-X). Addition of g-C 3 N 4 nanosheets improved the spinnability of nanofibers and augmented the ?-phase content of PVDF. The synthesized PGN non-woven mats were flexible and easily deformable without disrupting the continuity of fibers. Upon the addition of g-C 3 N 4 , tensile strength and thermal stability of nanocomposite fibers improved significantly. A maximum voltage output of ~7.5 V was generated for PGN nanogenerator which is ~8 times more than that of PVDF nanogenerator. Also, the PGN-X nanogenerator generated current output of 0.23 ?A and a power density of 0.22 ?W/cm ?2 . Improved physico-chemical characteristics and piezoelectric performance of PGN nanogeneratoris promising and makes it suitable for portable electronic and wearable devices. © 2019, The Polymer Society, Taipei.Item Exploring the synergistic interactions of TiO2, rGO, and g-C3N4 catalyst admixtures in a polystyrene nanocomposite photocatalytic film for wastewater treatment: Unary, binary and ternary systems(Elsevier Ltd, 2019) Das, S.; Mahalingam, H.Reduced graphene oxide (rGO) as well as graphitic carbon nitride (g-C3N4) were synthesised and blended along with TiO2 at specific ratios in polystyrene photocatalytic films to find out the optimum efficiency. The prepared photocatalysts were characterised by scanning electron microscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR) and contact angle analyser. The SEM, XRD, and FTIR analysis indicated that the nanoparticles were evenly distributed on the surface of the polystyrene film. The stability of the polymer film with respect to possible leaching of the embedded catalyst particles was evaluated by ICP-OES analysis. The photocatalytic activity of the admixture was evaluated using remazol turquoise blue dye as a model organic pollutant, and it was found that the photocatalytic ternary admixtures displayed much higher photocatalytic activity (99%) than the unary (89%) or binary (94%) mixtures indicating the synergistic effect of these catalysts. The effect of catalyst ratio, immobilisation, pH, initial dye concentration, irradiated light source, the presence of H2O2 and reusability of the film were also evaluated. The degradation of the dye is confirmed by TOC analysis (40% reduction), and HPLC/MS was used to identify the final degraded compounds. © 2019 Elsevier Ltd.Item PVDF Nanofibers with Embedded Polyaniline-Graphitic Carbon Nitride Nanosheet Composites for Piezoelectric Energy Conversion(American Chemical Society service@acs.org, 2019) Khalifa, M.; Anandhan, S.Herein, a facile approach was used to synthesize an ultrasensitive, durable, and flexible electrospun poly(vinylidene fluoride) (PVDF)/polyaniline (PANI)/graphitic carbon nitride nanosheets (g-C3N4) blend nanocomposite fibers (PPBF) based piezoelectric nanogenerator. PANI/g-C3N4 nanocomposite (PGNC) was prepared prior to its dispersal in PVDF. This unpretentious synthesis approach exploited the ?-nucleating activity of g-C3N4 along with the enhancement of electrical conductivity due to a network of PANI within individual PVDF nanofibers. Addition of PGNC and electrospinning synergistically enhanced the ?-phase content (?97%) of PVDF. The PPBF nanogenerator displayed remarkable improvement in the voltage and current output compared to pristine PVDF nanofibers (?1300%). The nanogenerator generated a voltage output of ?30 V and current output of 3.7 ?A with high stability and reproducibility (>50※000 cycles). The PPBF nanogenerator exhibited high-power density and conversion efficiency and was able to light up 70 commercial LEDs. The newly developed high performance nanogenerator could be a potential material in smart, self-powered wearable devices. © 2019 American Chemical Society.Item Novel immobilized ternary photocatalytic polymer film based airlift reactor for efficient degradation of complex phthalocyanine dye wastewater(Elsevier B.V., 2020) Das, S.; Mahalingam, H.Reduced graphene oxide (rGO) as well as graphitic carbon nitride (g-C3N4) catalysts were synthesized and a physical admixture of rGO and g-C3N4 along with TiO2 in the ratio of 1:1:1 by weight was immobilized in a polystyrene film using the facile solvent casting method. An internal loop airlift reactor with a working volume of 1.2 litres incorporating the prepared polymer-based photocatalytic film was designed and tested for the photocatalytic degradation of remazol turquoise blue dye synthetic wastewater. The reactor parameters affecting the photocatalytic activity such as airflow rate and Di/Do (ratio of draft tube diameter to outer tube diameter) were evaluated. The successful operation of the reactor obtained using the ternary immobilized catalyst mixture film gave 92.25% total organic carbon reduction and 94% decolourization within 140 min, compared to 91% decolourization by the slurry form within 40 min. Complete and quicker decolourization of the dye was also demonstrated under the influence of O3 or H2O2. The immobilized catalyst was successfully reused four times. The ternary catalyst admixture employed in this work and the unique design of the photocatalytic reactor helps to increase the degradation rate of toxic textile effluents thus making it suitable for larger scales of treatment. © 2019 Elsevier B.V.Item Strain-induced work function in h-BN and BCN monolayers(Elsevier B.V., 2020) Thomas, S.; Manju, M.S.; Ajith, K.M.; Lee, S.U.; Asle Zaeem, M.In the last decade, research activities of semiconducting two-dimensional (2D) electronic materials has received widespread attention, and the work function analysis is a significant parameter for investigating the feasible optoelectronic activity of these 2D materials. Here, we report a comparative study using ab-inito based density functional theory calculations to examine the impact of uniaxial and biaxial tensile and compressive strains on the work functions of boron nitride (h-BN) and boron carbonitride (BCN) monolayers. Unlike h-BN which has a large bandgap of 5 eV, the computed direct bandgap of BCN monolayer is 1.18 eV, which is beneficial for use in optoelectronic applications. We noticed that the calculated work function of both h-BN and BCN decreases (increases) continuously by increasing the compressive (tensile) strain irrespective of the strain directions. The observed variations in the work function in both h-BN and BCN are found to be related to the modulation of Fermi energy under compressive and tensile strains. The change in bond length between the atoms changes the total energy as a function of applied strain. Moreover, the direct bandgaps of both h-BN and BCN remain unaffected within the studied range of compressive and tensile strains, which can be beneficial for their use in photovoltaic devices. We also noticed that elastic modulus and Poisson's ratio are found to be anisotropic and decrease (increase) with the application of uniaxial tensile (compressive) strain. In addition, both h-BN and BCN possess high longitudinal and transverse wave velocities. The insight gained from this study will stimulate the research on BCN in view of relevant technological applications in the fields of nanoelectronics and optoelectronics. © 2020 Elsevier B.V.Item Graphitic C3N4/CdS composite photocatalyst: Synthesis, characterization and photodegradation of methylene blue under visible light(Elsevier B.V., 2020) Shenoy, S.; Tarafder, K.; Sridharan, K.Design and development of heterojunction photocatalysts is one among the main strategies for improving the photocatalytic activity of semiconductor materials. Here, we report the synthesis of a heterojunction photocatalyst by the embedment of cadmium sulphide (CdS) nanoparticles on the surface of graphitic carbon nitride (g-C3N4) layers through hydrothermal approach. The g-C3N4/CdS heterojunction photocatalyst exhibited two-fold and three-fold enhancement in the photodegradation efficiency in comparison to pristine CdS and g-C3N4, respectively in the removal of 20 ppm methylene blue dye molecules under visible light irradiation. The enhanced photocatalytic activity can be attributed to the formation of heterojunction and the synergistic effect of g-C3N4 and CdS in the promotion of charge separation and charge mobility that was tracked through photoluminescence spectroscopy. © 2020 Elsevier B.V.Item One-Dimensional Multichannel g-C3N4.7Nanostructure Realizing an Efficient Photocatalytic Hydrogen Evolution Reaction and Its Theoretical Investigations(American Chemical Society, 2021) Antil, B.; Kumar, L.; Ranjan, R.; Shenoy, S.; Tarafder, K.; Gopinath, C.S.; Deka, S.The emerging metal-free carbon nitride (C3N4) offers prominent possibilities for realizing the highly effective hydrogen evolution reaction (HER). However, its poor surface conductivity and insufficient catalytic sites hinder the HER performance. Herein, a one-dimensional vermicular rope-like graphitic carbon nitride nanostructure is demonstrated that consists of multichannel tubular pores and high nitrogen content, which is fabricated through a cost-effective approach having the final stoichiometry g-C3N4.7 for HER application. The present g-C3N4.7 is unique owing to the presence of abundant channels for the diffusion process, modulated surface chemistry with rich-electroactive sites from N-electron lone pairs, greatly reduced recombination rate of photoexcited exciton pairs, and a high donor concentration (4.26 × 1017 cm3). The catalyst offers a visible-light-driven photocatalytic H2 evolution rate as high as 4910 ? mol h-1 g-1 with an apparent quantum yield of 14.07% at band gap absorption (2.59 eV, 479 nm) under 7.68 mW cm-2 illumination. The number of hydrogen gas molecules produced is 1.307 × 1015 s-1 cm-2, which remained constant for a minimum of 18 h of repeated cycling in the HER without any degradation of the catalyst. In density functional theory calculations, a significant change in the band offset is observed due to N doping into the system in favor of electron catalysis. The theoretical band gap of a monolayer of g-C3N4.7 was enormously reduced because of the presence of additional densities of states from the doped N atom inside the band gap. These impurity or donor bands are formed inside the band gap region, which ultimately enhance the hydrogen ion reduction reaction enormously. © 2021 American Chemical Society.