Copyright (c) 2025 V.Radha Jayalakshmi, N. Jeyakumaran

This work is licensed under a Creative Commons Attribution 4.0 International License.
Tailoring NiO Thin Films: Citric Acid-Assisted Synthesis and Cobalt Doping for Enhanced Properties
Corresponding Author(s) : N. Jeyakumaran
Asian Journal of Chemistry,
Vol. 37 No. 10 (2025): Vol 37 Issue 10, 2025
Abstract
This study investigates the cobalt doped nickel oxide ssthin films synthesis using a sol-gel method using citric acid as chelating agent combined with spin-coating techniques. The structural, chemical and morphological characteristics of pure NiO, 1%, 3%, 5% and 7% Co doped NiO thin films were examined. Also, effects of annealing temperatures (400 ºC, 500 ºC and 600 ºC) were studied on pure NiO and Co doped NiO. X-ray diffraction (XRD) confirmed a polycrystalline cubic structure with increased crystallinity and the reduced defect states were observed at higher annealing temperatures, particularly at 600 ºC. The UV Visible spectroscopy results revealed the significant transmittance in annealed NiO thin films, with the band gap energy decreasing from 3.72 eV to 2.89 eV as the annealing temperature increased. The X-ray photoelectron spectroscopy (XPS), O 1s spectra revealed the presence of lattice oxygen, surface hydroxyl groups and Ni2O3, with a significant reduction in surface hydroxylation as the annealing temperature increased. Similarly, the Ni 2p spectra showed a decrease in satellite peak intensity, indicating a transition to a more crystalline NiO structure. These results highlight the critical role of annealing temperature and Co doping in tailoring the structural and surface properties of NiO thin films, paving the way for their potential applications in advanced optoelectronic and energy devices.
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I. Leonov, A.O. Shorikov, V.I. Anisimov and I.A. Abrikosov, Phys. Rev. B, 101, 245144 (2020); https://doi.org/10.1103/PhysRevB.101.245144
P. Liu, C. Franchini, M. Marsman, and G. Kresse, J. Phys.: Condens. Matter, 32, 015502 (2020); https://doi.org/10.1088/1361-648X/ab4150
L. Chen, Z. Liu, Z. Guo and X.-J. Huang, J. Mater. Chem. A Mater. Energy Sustain., 8, 17326 (2020); https://doi.org/10.1039/D0TA05539E
Karishma, N. Tripathi, R.K. Pandey, A. Tripathi, K. Asokan, V. Bhushan and V. Sharma, Energy Storage, 6, 70065 (2024); https://doi.org/10.1002/est2.70065
M.I. Hossain and B. Aissa, Processess, 12, 2809 (2024); https://doi.org/10.20944/preprints202411.1284.v1
K.O. Egbo, C.E. Ekuma, C.P. Liu and K.M. Yu, Phys. Rev. Mater., 4, 104603 (2020); https://doi.org/10.1103/PhysRevMaterials.4.104603
M. Napari, T.N. Huq, T. Maity, D. Gomersall, K.M. Niang, A. Barthel, J.E. Thompson, S. Kinnunen, K. Arstila, T. Sajavaara, R.L.Z. Hoye, A.J. Flewitt and J.L. MacManus-Driscoll, InfoMat, 2, 769 (2020); https://doi.org/10.1002/inf2.12076
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D.S. Mann, S. Thakur, S.S. Sangale, K.-U. Jeong, S.-N. Kwon and S.-I. Na, Small, 20, 2405953 (2024); https://doi.org/10.1002/smll.202405953
J. Dong, S. Guo, Z. He, Z. Jiang and J. Jia, J. Solid State Chem., 339, 124948 (2024); https://doi.org/10.1016/j.jssc.2024.124948
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W.-S. Chen, S.-H. Yang, W.-C. Tseng, W. W.-S. Chen, and Y.-C. Lu, ACS Omega, 6, 13447 (2021); https://doi.org/10.1021/acsomega.1c01618
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M.Y. Khan, M.W. Akhtar, M.F.A. Khan, Z. Abbass, F. Rasheed, M.S. Ali, N. Pirzada and R. Shahbaz, Mehran Univ. Res. J. Eng. Technol., 43, 150 (2024); https://doi.org/10.22581/muet1982.3149
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N.R. Aswathy, J. Varghese and R. Vinodkumar, J. Mater. Sci. Mater. Electron., 31, 16634 (2020); https://doi.org/10.1007/s10854-020-04218-5
M.M. Gomaa, G. Reza-Yazdi, M. Rodner, G. Greczynski, M. Boshta, M.B.S. Osman, V. Khranovskyy, J. Eriksson and R. Yakimova, J. Mater. Sci. Mater. Electron., 29, 11870 (2018); https://doi.org/10.1007/s10854-018-9287-6
F. Hajakbari, M. Taheri Afzali and A. Hojabri, Acta Phys. Pol. A, 131, 417 (2017); https://doi.org/10.12693/APhysPolA.131.417
C.H. Hsu, K.T. Chen, P.H. Huang, W.Y. Wu, X.Y. Zhang, C. Wang, L.S. Liang, P. Gao, Y. Qiu, S.Y. Lien, Z.B. Su, Z.-R. Chen and W.-Z. Zhu, Nanomaterials, 10, 1322 (2020); https://doi.org/10.3390/nano10071322
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S. Yang, Y. Liu, Y. Zhang and D. Mo, Bull. Mater. Sci., 33, 209 (2010); https://doi.org/10.1007/s12034-010-0032-x
V.P. Patil, S. Pawar, M. Chougule, P. Godse, R. Sakhare, S. Sen and P. Joshi, J. Surf. Eng. Mater. Adv. Technol., 1, 35 (2011); https://doi.org/10.4236/jsemat.2011.12006
J. Feldl, M. Budde, C. Tschammer, O. Bierwagen and M. Ramsteiner, J. Appl. Phys., 127, 235105 (2020); https://doi.org/10.1063/5.0006085
L. Cao, D. Wang and R. Wang, Mater. Lett., 132, 357 (2014); https://doi.org/10.1016/j.matlet.2014.06.114
M.A.R. Abdullah, M.H. Mamat, A.S. Ismail, M.F. Malek, S.A.H. Alrokayan, H.A. Khan and M. Rusop, AIP Conf. Proc., 1733, 020013 (2016); https://doi.org/10.1063/1.4948831
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