Faculty Publications

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Author: search.filters.author.Udayashankar, N.K.Subject: search.filters.subject.Copper compounds

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    Role of soaking time on the phase evolution of Cu2ZnSnS4 polycrystals synthesized using melting route for photovoltaic applications
    (Elsevier Ltd, 2019) Choudhari, N.J.; Raviprakash, Y.; Fernandes, B.J.; Udayashankar, N.K.
    Cu2ZnSnS4(CZTS) is an emerging quaternary semiconductor material to use as absorber layer for solar cells due its suitable band gap, high absorption coefficient, earth abundancy and less toxic nature. This work provides a comprehensive insight into the phase evolution of CZTS synthesized at a relatively lower process time. In this study, CZTS bulk polycrystals were synthesized using elemental pre cursors via melting route. The influence of soaking time on the structural, compositional and optical properties were investigated using XRD, EDS, Raman, DRS, PL and XPS measurements. XRD pattern revealed a highly crystalline tetragonal structure corresponding to kesterite phase. EDS mapping were performed over a large area of the sample revealed homogeneous distribution and near stoichiometric composition for the sample soaked for 14 h (S14). Raman spectra confirmed the existence of single phase CZTS without any secondary and ternary phases for S14. Diffuse reflectance spectroscopy gave a band gap value in the range 1.34–1.39 eV. PL analysis revealed that asymmetric band shape and higher energy shift is the characteristics of radiative transitions which are influenced by fluctuating potentials. XPS studies confirmed the oxidation states as Cu(I), Zn(II), Sn(IV) and S(II). © 2019 Elsevier B.V.
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    Mechanistic insights and DFT analysis of bimetal doped styrofoam-like LaFeO3 perovskites with in-built dual redox couples for enhanced Photo-Fenton degradation of Tetracycline
    (Elsevier B.V., 2024) James, A.; Naik, S.; Rodney, J.D.; Joshi, S.; Udayakumar, U.; Kim, B.C.; Udayashankar, N.K.
    The rising number of contaminants released into the environment and the inadequacies of traditional wastewater treatment techniques have led to the demand for enhanced oxidation technologies like photo-Fenton. In this study, bimetal co-doped lanthanum orthoferrite (BixLa1-xCuyFe1-yO3 (x = 0, 0.01, 0.05, 0.1; y = 0, 0.01, 0.05, 0.1, 0.15)) based photo-Fenton catalysts with the in-built redox couples Fe3+/Fe2+, Cu2+/Cu+ and oxygen vacancies have been successfully synthesised via a facile one-pot solution combustion route. Systematic studies show that the Bi0.05La0.95Cu0.1Fe0.9O3 (LFOBC) exhibits an optimal photo-Fenton degradation rate of 0.0497/min for Tetracycline (TC) removal, being ∼ 1.8 and ∼ 6.2 times greater than Bi0.05La0.95FeO3 (LFOB) and pristine LaFeO3 (LFO) respectively. DFT analysis confirmed the better adsorption and dissociation of H2O2 on a bimetal co-doped catalyst and identified the electron density difference in LFOBC, which can induce the H2O2 dissociation. A detailed investigation of various influencing reaction parameters is explored. The degradation pathway for the LFOBC catalyst with the toxicological characteristics of each intermediate is analysed. This study presents the Bi0.05La0.95Cu0.1Fe0.9O3 as a potential photocatalyst for enhanced photo-Fenton degradation with excellent efficiency observed for the degradation of various harmful pollutants for environmental remediation. © 2024 Elsevier B.V.
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    Cu- and Bi-codoped LaFeO3-Decorated MXene Nanosheets for Photo-Fenton Catalysis and Hydrogen Evolution
    (American Chemical Society, 2025) James, A.; Ray, S.; Rodney, J.D.; Carva, K.; Udayashankar, N.K.; Kim, B.C.
    The increasing release of contaminants into the environment and the demand for sustainable energy solutions have prompted the exploration of advanced oxidation methods such as photo-Fenton and photoelectrochemical water splitting. Herein, hierarchical heterostructures of Cu- and Bi-codoped LaFeO3(Bi0.05La0.95Cu0.1Fe0.9O3) (LFOBC)-decorated Ti3C2(MXene) nanosheets were developed by a low-cost one-pot combustion approach. The optimized LFOBC/Mx-7 (Bi0.05La0.95Cu0.1Fe0.9O3/Ti3C2-7) composite demonstrated superior photo-Fenton degradation of tetracycline (TC), achieving 1.69 times higher efficiency than LFOBC and 10.65 times more efficiency than pristine LaFeO3(LFO). This enhanced performance is attributed to strong interfacial coupling, which suppressed photoexcited carrier recombination, as confirmed by PL, TRPL, EIS, and photocurrent studies. Experimental and theoretical work function analyses revealed band bending and the formation of an Ohmic junction at the interface. Furthermore, a degradation mechanism and a reaction pathway were proposed, and the reduction in toxicity levels was identified. The LFOBC/Mx-7 catalyst also exhibited promising results for H2evolution with an overpotential of 156 mV vs RHE under visible-light illumination, which was 2.37 times less than that of LFOBC. These results, therefore, showcase the LFOBC/Mx composite as a multifunctional photocatalyst for both pollutant degradation and sustainable energy generation. © 2025 American Chemical Society