DFT+U Investigation of Electronic Properties of CuO/Fe₂O₃ Heterojunction: Band Gap Engineering and Charge Transfer Mechanism for Photocatalytic Water Splitting
DOI:
https://doi.org/10.31958/js.v18i1.17327Keywords:
DFT U, α-Fe2O3, water splitting, CuO/Fe2O3 heterojunction, band-gap engineering, S-schemeAbstract
The development of efficient, earth-abundant photocatalysts for solar water splitting remains a central challenge in renewable-energy research. The electronic properties of , a heterojunction, and the adsorption of water-derived species on the surface were investigated using spin-polarized first-principles calculations within the DFT+U framework, as implemented in the Vienna Ab initio Simulation Package (VASP) with the GGA-PBE functional and Hubbard corrections of U = 5.3 eV (Fe-3d) and U=6.5 eV (Cu-3d). The pristine slab exhibits an indirect band gap of 1.28 eV, with the valence band maximum (VBM) at Γ and the conduction band minimum (CBM) between Y and Γ; the valence band is dominated by O-2p states and the conduction band by Fe-3d states, while symmetric spin channels confirm its antiferromagnetic character. Formation of the heterojunction widens the indirect gap to 1.61 eV (Δ= +0.33 eV), driven by hybridization of Cu-3d and Fe-3d orbitals that lifts the lower conduction band, with empty Cu-s states appearing near 2.8 eV above the Fermi level. The orbital redistribution is suggestive of an S-scheme charge-transfer mechanism in which CuO acts as the reduction photocatalyst and as the oxidation photocatalyst. Among the adsorbed species, the interaction strength increases in the order < • < •, with • showing the strongest Fe–O orbital hybridization. The gap remains below experimental value (2.1 eV). These results point to as candidate visible-light S-scheme photocatalyst for the oxygen evolution reaction, while a quantitative assessment of the reaction is left for future work.
References
Alamgir, Mushtaq, N., Ahmad, A., Erum, J. K. E., Li, L., Qian, J., Wang, X., & Gao, J. (2025). Shaping the future of solar-driven photocatalysis by reticular framework materials. Journal of Materials Science & Technology, 231, 193–244. https://doi.org/10.1016/j.jmst.2025.02.009
Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review. B, Condensed Matter, 50(24), 17953–17979. https://doi.org/10.1103/physrevb.50.17953
Dudarev, S., & Botton, G. (1998). Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U study. Physical Review B - Condensed Matter and Materials Physics, 57(3), 1505–1509. https://doi.org/10.1103/PhysRevB.57.1505
Fujishima, A., & Honda, K. (1972). Electrochemical Photolysis of Water at a Semiconductor Electrode. Nature, 238(5358), 37–38. https://doi.org/10.1038/238037a0
Gao, R.-T., Zhang, J., Nakajima, T., He, J., Liu, X., Zhang, X., Wang, L., & Wu, L. (2023). Single-atomic-site platinum steers photogenerated charge carrier lifetime of hematite nanoflakes for photoelectrochemical water splitting. Nature Communications, 14(1), 2640. https://doi.org/10.1038/s41467-023-38343-6
Guo, Y., Tan, X., Yu, T., & Gong, J. (2026). Recent Advances of Photocatalytic Hydrogen Evolution via Water Vapor Splitting. Advanced Functional Materials, 36(17), e22276. https://advanced.onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202522276
Hofmann, O. T., Zojer, E., Hörmann, L., Jeindl, A., & Maurer, R. J. (2021). First-principles calculations of hybrid inorganic-organic interfaces: From state-of-the-art to best practice. Physical Chemistry Chemical Physics, 23(14), 8132–8180. https://doi.org/10.1039/d0cp06605b
Huang, X., Ramadugu, S. K., & Mason, S. E. (2016). Surface-Specific DFT + U Approach Applied to α-Fe2O3(0001). The Journal of Physical Chemistry C, 120(9), 4919–4930. https://doi.org/10.1021/acs.jpcc.5b12144
Jiang, Z., , Zhang, L., & Yu, J. (2023). Research Progress on S-Scheme Heterojunction Photocatalyst. Journal of the Chinese Ceramic Society, 51(1), 73–81. https://doi.org/10.14062/j.issn.0454-5648.20220459
Kresse, G., & Hafner, J. (1993). Ab initio molecular dynamics for liquid metals. Phys. Rev. B, 47(1), 558–561. https://doi.org/10.1103/PhysRevB.47.558
Kyesmen, P. I., Nombona, N., & Diale, M. (2021). Heterojunction of nanostructured α-Fe2O3/CuO for enhancement of photoelectrochemical water splitting. Journal of Alloys and Compounds, 863, 158724. https://www.sciencedirect.com/science/article/pii/S0925838821001316
Low, J., Yu, J., Jaroniec, M., Wageh, S., & Al-Ghamdi, A. A. (2017). Heterojunction Photocatalysts. Advanced Materials, 29(20), 1601694. https://doi.org/https://doi.org/10.1002/adma.201601694
Lv, D., Gao, J., Shao, Y., Wang, Y., Pan, J., Cong, Y., & Lv, S.-W. (2025). Internal electric field triggered charge redistribution in CuO/Fe(2)O(3) composite to regulate the peroxymonosulfate activation for enhancing the degradation of organic pollutants. Environmental Pollution (Barking, Essex : 1987), 367, 125618. https://doi.org/10.1016/j.envpol.2024.125618
Monkhorst, H. J., & Pack, J. D. (1976). Special points for Brillouin-zone integrations. Phys. Rev. B, 13(12), 5188–5192. https://doi.org/10.1103/PhysRevB.13.5188
Nallapureddy, R. R., Arla, S. K., Ibáñez, A., Pabba, D. P., Jung, J. H., & Joo, S. W. (2025). Photosensitizer and Charge Separator Roles of g-C₃N₄ Integrated into the CuO-Fe₂O₃ p-n Heterojunction Interface for Elevating PEC Water Splitting Potential. Nanomaterials, 15(7), 1–16. https://doi.org/10.3390/nano15070551
Naveas, N., Pulido, R., Marini, C., Hernández-Montelongo, J., & Silván, M. M. (2023). First-principles calculations of hematite (α-Fe2O3) by self-consistent DFT+U+V. IScience, 26(2). https://doi.org/10.1016/j.isci.2023.106033
Nørskov, J. K., Rossmeisl, J., Logadottir, A., Lindqvist, L., Kitchin, J. R., Bligaard, T., & Jónsson, H. (2004). Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode. The Journal of Physical Chemistry. B, 108(46), 17886–17892. https://doi.org/10.1021/jp047349j
Perdew, J. P., Burke, K., & Ernzerhof, M. (1996). Generalized Gradient Approximation Made Simple. Phys. Rev. Lett., 77(18), 3865–3868. https://doi.org/10.1103/PhysRevLett.77.3865
Sivula, K., Le Formal, F., & Grätzel, M. (2011). Solar Water Splitting: Progress Using Hematite (α-Fe2O3) Photoelectrodes. ChemSusChem, 4(4), 432–449. https://doi.org/https://doi.org/10.1002/cssc.201000416
Tanwar, K., Lo, C., Eng, P., Catalano, J., Walko, D., Brown, G., Waychunas, G., Chaka, A., & Trainor, T. (2007). Surface diffraction study of the hydrated hematite (1-102) surface. Surface Science, 601, 460–474. https://doi.org/10.1016/j.susc.2006.10.021
Walter, M. G., Warren, E. L., McKone, J. R., Boettcher, S. W., Mi, Q., Santori, E. A., & Lewis, N. S. (2010). Solar Water Splitting Cells. Chemical Reviews, 110(11), 6446–6473. https://doi.org/10.1021/cr1002326
Wang, V., Xu, N., Liu, J.-C., Tang, G., & Geng, W.-T. (2021). VASPKIT: A user-friendly interface facilitating high-throughput computing and analysis using VASP code. Computer Physics Communications, 267, 108033. https://doi.org/https://doi.org/10.1016/j.cpc.2021.108033
Xu, Q., Zhang, L., Cheng, B., Fan, J., & Yu, J. (2020). S-Scheme Heterojunction Photocatalyst. Chem, 6(7), 1543–1559. https://doi.org/https://doi.org/10.1016/j.chempr.2020.06.010
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Maulana Reizqy Anughrah, Riri Jonuarti, Leni Azius Fitri, Eka Susanti
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work.
