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 Bi-functional LaMxFe1-xO3 (M = Cu, Co, Ni) for photo-fenton degradation of methylene blue and photoelectrochemical water splitting(Elsevier Ltd, 2023) James, A.; Rodney, J.D.; Rao, L.; Badekai Ramachandra, B.R.; Udayashankar, N.K.Due to growing concern over environmental remediation and the energy crisis, perovskite nanoparticles have gained wide interest in converting solar energy to sustainable fuel and also in degrading organic effluents. Herein, we report the synthesis and bi-functional activity of one-pot-glycine combustion derived LaMxFe1-xO3 (M = Cu, Co, Ni; x = 0, 0.01) for photo-Fenton degradation of Methylene Blue (MB) and photoelectrochemical water splitting. When used as a photocatalyst, with partial substitution of Cu even at a lower concentration, LaCu0.01Fe0.99O3 has exhibited excellent degradation efficiency of 96.4% in 90 min, which is 2.5 times better than the LaFeO3. On the other hand, Co and Ni modified LaFeO3 photocatalysts have demonstrated prominent activities with degradation efficiency of 93.8% and 74.8% respectively within 180 min of visible light irradiation. The retention and reusability analysis showed that LaCu0.01Fe0.99O3 is stable against photo corrosion and remains unchanged after 5 consecutive cycles of MB dye degradation. In addition, LaCu0.01Fe0.99O3 is complimented as a single catalyst for dual functions such as photocatalysis and electrocatalysis, both of which are assisted by visible light. Under illumination, the overpotential (η) improved from 507.6 mV vs RHE (dark) to 498.1 mV vs RHE (light) for O2 evolution and 220.5 mV vs RHE (dark) to 182.8 mV vs RHE (light) for H2 generation respectively. The light response of the catalyst and improvement in activity is validated by the significant enhancement in current density under exposure at both half cycle of chronoamperometry. © 2023 Hydrogen Energy Publications LLCItem Kinetic Comparison of Photocatalysis with the Photo-Fenton Process on the Removal of Tetracycline Using Bismuth-Modified Lanthanum Orthoferrite Nanostructures(American Chemical Society, 2024) James, A.; Rodney, J.D.; Udayashankar, N.K.In this study, we investigate visible-light-driven photocatalytic and photo-Fenton degradation of tetracycline (TC) using bismuth-impregnated lanthanum orthoferrite (BixLa1-xFeO3 (x = 0, 0.01, 0.05, 0.07)) nanostructures. Bi doping significantly improves the removal of TC, with Bi0.05La0.95FeO3 (LFO-Bi5) exhibiting optimal degradation. In both photocatalysis (PC) and photo-Fenton catalysis (PFC), the reaction follows pseudo-first-order kinetics, with LFO-Bi5 showing rate constants of 0.0065/min for PC and 0.02716/min for PFC, surpassing LaFeO3 by 2.76 and 3.43 times, respectively. The long-term presence of photoexcited carriers in LFO-Bi5 is confirmed through transient PL, TRPL, and EIS studies. The superior degradation capabilities are attributed to radicals in photocatalysis and OH• radicals in photo-Fenton catalysis. The PFC exhibited faster kinetics due to the rapid production of OH• radicals via the Fe-redox cycle and direct dissociation of H2O2 at oxygen vacancies. LFO-Bi5 demonstrates excellent photostability and reusability for up to six consecutive cycles. The degradation pathway and toxicological properties of the intermediates are analyzed, highlighting the potential of LFO-Bi5 catalysts in antibiotic-contaminated water treatment. © 2024 American Chemical Society.Item An insight into noticeable dielectric response and effect of fe doping on photocatalytic efficiency (visible light) of ZnO nanoparticles synthesized through solution precipitation for harmful textile dye degradation(Springer Science and Business Media B.V., 2024) Mahendra, K.; Fernandes, J.M.; James, A.; B.s, N.; Pattar, J.; Sunitha, D.V.; Gopal, K.; Udayashankar, N.K.Iron (Fe)-incorporated zinc oxide (ZnO) nanoparticles (NPs) were synthesized via chemical precipitation technique and studied using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and UV–vis diffuse reflectance spectroscopy. PXRD analysis reveals a hexagonal wurtzite structure for all the synthesized samples. UV–visible measurements demonstrate a reduction in the bandgap of ZnO with an increase in Fe concentration. The ZnO and Fe-incorporated ZnO NPs are studied for the degradation of organic textile dye under visible light irradiation. All the nanoparticles are thoroughly investigated using impedance and dielectric measurements in the frequency range of 20 Hz to 1 MHz. The results obtained are compared, interpreted, and presented in this paper. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.Item Investigation of ZnO Nanoparticles Synthesized with Different Concentrations of NaOH for Dielectric and Photocatalytic Applications(Springer Science and Business Media Deutschland GmbH, 2025) Mahendra, K.; Fernandes, J.M.; James, A.; Nagaraja, B.S.; Pattar, J.; Udayashankar, N.K.In this study, ZnO nanoparticles are synthesized for photocatalytic and dielectric applications using precipitation technique. The properties of ZnO nanoparticles are investigated for various sodium hydroxide (NaOH) concentrations. The powder X-ray diffraction (PXRD) method is employed to analyse structural properties. PXRD reveals the decrease in cell volume from 47.92 to 47.73 Å and crystallite size varied from 31.96 to 22.53 nm. The scanning electron microscope (SEM) study explained the morphology and EDS measurements revealed the presence of zinc and oxygen distribution on the surface. Further, the particle size is also calculated to be 62.23 nm, 50.16 nm, 46.86 nm and 47.43 nm respectively. The diffuse reflectance spectroscopy (UV-DRS) study indicates that, as NaOH concentration increases, the optical bandgap of the ZnO nanoparticles decreases from 3.25 eV to 3.12 eV. The PL studies revealed blue emission for all ZnO nanoparticles. I–V measurements indicate improved conductivity for higher concentrations of NaOH. A photocatalyst (as synthesized) is examined in the presence of UV radiation for its ability to photodegrade organic pollutants (Methylene Blue dye) with adsorption capacity of 19.7%, 20.3%, 21.48% and 22.97% respectively. The increased adsorption could be due to the increased surface area of the samples. Further, the dielectric properties of the synthesized nanoparticles, including impedance, dielectric constant, conductivity, dielectric loss, and electric modulus is established and examined. © The Tunisian Chemical Society and Springer Nature Switzerland AG 2025.