Thermal Oxidation-Driven Phase Control of CuO-Cu2O Hybrids on Copper Substrates for Tunable Optical Functionalities
DOI:
https://doi.org/10.48048/tis.2026.11806Keywords:
Phase transition, CuO-Cu2O heterostructures, Phase-controlled synthesis, Thermal oxidation, Tunable optical functionalitiesAbstract
CuO-Cu2O hybrid materials were developed through a simple single-step thermal oxidation process of copper plates. Copper substrates were annealed at a temperature range of 300 to 700 °C. To investigate the temperature-driven transitions in oxide composition, crystallography, and photonic response, various analytical techniques were employed. X-ray diffraction (XRD) confirmed the progressive transformation, accompanied by changes in phase fraction and structural modification. Fourier-transform infrared spectroscopy (FT-IR) and photoluminescence (PL) identified vibrational and emission features associated with bonding and oxide defect states, respectively. UV-Vis spectroscopy revealed a tunable bandgap between 2.60 and 2.55 eV, influenced by phase composition. Improved optical functions were observed at different heating temperatures. In this study, the thermal oxidation of a copper plate is proposed as a scalable strategy for phase-controlled oxide synthesis, suggesting that the synthesized CuO-Cu2O hybrids are considered for application in opto-related technology.
HIGHLIGHTS
- Oxidation driven by temperature showed the formation of CuO and Cu2O at 500 °C. At 700 °C, Cu2O remains the main phase because gas exchange is limited by phase equilibrium.
- Oxide phases reveal at 700 °C heating present the most significant lattice improvement.
- SEM analysis showed dense, fine grains at 300 °C transforming into larger, porous crystallites (400 nm) at 700 °C, indicating lattice strain relaxation and recrystallization.
- Tailored optical behavior with bandgap modulation from 2.69 to 2.55 eV with increasing heating temperature.
- At 700 °C heating, skin depth increased and optical density reduced, reflecting superior light penetration and low photon scattering.
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Q Su, C Zuo, M Liu and X Tai. A review on Cu2O-based composites in photocatalysis: Synthesis, modification, and applications. Molecules 2023; 28(14), 5576.
V Molahalli, A Sharma, K Bijapur, G Soman, A Shetty, B Sirichandana, BGM Patel, N Chattham and G Hegde. Properties, synthesis, and characterization of Cu-based nanomaterials, copper-based nanomaterials in organic transformations. American Chemical Society 2024; 1466, 1-33.
Y Yang, D Xu, Q Wu and P Diao. Cu2O/CuO bilayered composite as a high-efficiency photocathode for photoelectrochemical hydrogen evolution reaction. Scientific Reports 2016; 6(1), 35158.
R Sirirak, P Chaopanich, A Prasatkhetragarn, C Chailuecha, S Kuimalee and A Klinbumrung. Doping effect of Zn on structural and optical properties of CuO nanostructures prepared by wet chemical precipitation process. Radiation Physics and Chemistry 2022; 190, 109788.
CV Niveditha, MJ Jabeenfatima and S Sindhu. Electrochemical synthesis of p-type copper oxides. Наносистемы: физика, химия, математика 2016; 7(4), 747-751.
KF Genaro-Saldivar, GR Negrete-Reyes, E Ramirez-Meneses, C Juarez-Balderas, F Avendano-Sanjuan, DA Garcia-Najera and JG Ibanez. Simultaneous anodic and cathodic electrodeposition of cu2o for solar energy conversion. Kimya Problemleri 2024; 22(4), 447-457.
S Jurečka, PP Sahoo and P Čendula. Optical and microstructural properties of electrodeposited cuprous oxide. Applied Physics A 2024; 130(3), 179.
M Abd Elkodous, G Kawamura, WK Tan and A Matsuda. Facile 1-pot preparation of Cu/CuO/Cu2O heterojunction for photocatalytic applications. Materials Letters 2022; 323, 132606.
SY Wang, JR Zhang, G Ge and W Hua. Deciphering the Cu(I):O2 to Cu(II):O2− transition along the binding pathway through computational transient x-ray absorption spectra. ChemRxiv 2025. https://doi:10.26434/chemrxiv-2025-8v846
ZL Croft, O Valenzuela, C Thompson, B Whitfield, G Betzko and G Liu. Copper oxidation-induced nanoscale deformation of electromechanical, laminate polymer/graphene thin films during thermal annealing: Implications for flexible, transparent, and conductive electrodes. ACS Applied Nano Materials 2024; 7(24), 28829-28840.
VH Castrejón-Sánchez, AC Solis, R López, C Encarnación-Gomez, F Morales Morales, OS Vargas, JE Mastache-Mastache and GV Sánchez. Thermal oxidation of copper over a broad temperature range: Towards the formation of cupric oxide (CuO). Materials Research Express 2019; 6(7), 075909.
B Maack and N Nilius. Morphological and kinetic insights into Cu2O-CuO oxidation. Physica Status Solidi (b) 2019; 257(1), 1900365.
CJ Chang, CW Kang and A Pundi. Effect of calcination-induced oxidation on the photocatalytic H2 production performance of cubic Cu2O/CuO composite photocatalysts. Catalysts 2024; 14(12), 926.
FC Akkari, M Kanzari and B Rezig. Preparation and characterization of obliquely deposited copper oxide thin films. The European Physical Journal-Applied Physics 2007; 40(1), 49-54.
H Jabraoui, MD Rouhani, C Rossi and A Estève. First-principles investigation of CuO decomposition and its transformation into Cu2O. Physical Review Materials 2022; 6(9), 096001.
HM Rietveld. Line profiles of neutron powder-diffraction peaks for structure refinement. Acta Crystallographica 1967. https://doi.org/10.1107/S0365110X67000234
L Lutterotti. Maud: A rietveld analysis program designed for the internet and experiment integration. Acta Crystallographica Section A - Acta Crystallogr A 2000; 56, s54.
D Chen, Z Ye, J Xu, S Ma and J Zhang. In situ reconstructed prism-like CuO on copper foam assisted by fumaric acid for an enhanced electrochemical nitrate reduction reaction. Dalton Transactions 2025; 54(8), 3500-3508.
M Rafei, V Miranda la Hera, H Reza-Barzegar, E Gracia-Espino and T Wågberg. Study on the electronic and structural properties of oxidized copper films. AIP Advances 2022; 12, 10.
BH Toby. R factors in rietveld analysis: How good is good enough. Powder Diffraction 2006; 21(1), 67-70.
P Katekaew, A Prasatkhetragarn, R Sirirak, C Boonruang and A Klinbumrung. Role of the thermal regime in the defect formation of zinc oxide nanostructures prepared by the thermal decomposition process. Zeitschrift für Physikalische Chemie 2023; 237(8), 1077-1104.
Y Keereeta, W Panthuwat, T Suriwong, R Sirirak, A Prasatkhetragarn, C Boonruang and A Klinbumrung. Phase transition and optical characteristics of Mg doped CuAlO2 synthesized by facile thermal decomposition process. Optik 2022; 268, 169840.
S Krobthong, K Umma, T Rungsawang, T Mirian, S Wongrerkdee, S Nilphai, K Hongsith, C Raktham and P Pimpang. Synthesis and characterization of Cu2O and CuO nanoparticles in distilled water using electrochemical process. Digest Journal of Nanomaterials and Biostructures 2025; 20(1), 13-21.
VHA Tran, T Duc, H Tran, A Duc, A Alshehri, VT Tran, T Nguyen, C Pham and VH Nguyen. Atmospheric pressure spatial atomic layer deposition of p-type CuO thin films from copper (II) acetylacetonate and ozone for UV detection. Dalton Transactions 2025; 54(8), 3266-3276.
KS Finnie, DJ Cassidy, JR Bartlett and JL Woolfrey. IR spectroscopy of surface water and hydroxyl species on nanocrystalline TiO2 films. Langmuir 2001; 17(3), 816-820.
X Zhao, P Wang, Z Yan and N Ren. Room temperature photoluminescence properties of CuO nanowire arrays. Optical Materials 2015; 42, 544-547.
A Agarwal, S Ramachandran, S Kumar, S Swaminathan and R Raghavendra. A comparative study on Centella Asiatica‐mediated green synthesis of silver and copper oxide nanoparticles: Implications for wound healing. Particle & Particle Systems Characterization 2025; 4(6), 2400215.
J Lu, Y Ren, LWang, L Zou, J Liang, X Liang, Y Gao, F Li, J Gao, A Terfort and J Liu. Adjusting the ratio of oxidation states in a CuO@Cu2O for the optimization of electrocatalytic CO2 conversion to ethylene. ChemSusChem 2025; 18(10), e202401963.
LE Román, C Uribe, F Paraguay-Delgado, JG Sutjianto, AM Navarrete-López, ED Gomez, JL Solís and MM Gómez. Physical and surface chemical analysis of high-quality antimicrobial cotton fabrics functionalized with CuOx grown in situ from different copper salts: Experimental and theoretical approach. ACS Applied Materials & Interfaces 2024; 17(1), 1869-1882.
S Dhungana, A Gauli, L Tiwari, D Khadka, S K Gautam, M Pokhrel, J Baral and B Poudel. Synthesis and characterization of copper oxide nanoparticles isolated from Acmella oleracea and study of antimicrobial and phytochemical properties. Amrit Research Journal 2025; 5(1), 18-29.
G Burns. Solid state physics. Academic Press, California, United States, 1990, p. 447-527.
Y Keereeta, R Sirirak and A Klinbumrung. Revealing effect of cobalt dopant on crystallography and optical characteristics of nanostructured cupric oxide. Micro and Nanostructures 2024; 186, 207757.
N Abraham, C Unni and D Philip. Studies on bandgap tuning of visible light active heterojunction CuO/ZnO nanocomposites for DSSC application. Journal of Materials Science: Materials in Electronics 2018; 29(24), 21002-21013.
M Mattsson, M Kham, J Parker, D Meeth, J Wager, A Flewitt and M Graham. Defect density of states of tin oxide and copper oxide p-type thin-film transistors. Advanced Electronic Materials 2024; 11(11), 2400929.
S Boonphan, S Prachakiew, C Nontakoat, Y Keereeta, C Boonruang and A Klinbumrung. Crystallographic defects induced F-Center and optical enhancements in CeO2-TiO2 nanocomposites. South African Journal of Chemical Engineering 2025; 52, 68-79.
AS Hassanien and AA Akl. Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films. Superlattices and Microstructures 2016; 89, 153-169.
M Ditta, MA Farrukh, S Ali and N Younas. X-ray peak profiling, optical parameters and catalytic properties of pure and CdS doped ZnO-NiO nanocomposites. Russian Journal of Applied Chemistry 2017; 90(1), 151-159.
KN Manjunatha and S Paul. Investigation of optical properties of nickel oxide thin films deposited on different substrates. Applied Surface Science 2015; 352, 10-15.
BM Ouarda, A Ouahab, R saâd, S Hettal, K Aicha, M Sayad, H Attouche and N Gherraf. Optoelectronic and dielectric properties of tenorite CuO thin films sprayed at various molar concentrations. Periodica Polytechnica Chemical Engineering 2024; 68(1), 93-105.
I Stambouli, M Zerouali, R Daïra, D Bouras, GA El-Hiti, S Grigorian and M Fellah. Enhancement of tin-doping on the structural, electrical, and optical properties of copper oxide thin films for optoelectronic applications. Ceramics International 2025; 51(13), 17689-17703.
A Gloystein, M Soltanmohammadi and N Nilius. Light emission from single oxygen vacancies in Cu2O films probed with scanning tunneling microscopy. The Journal of Physical Chemistry Letters 2023; 14(17), 3980-3985.
GK Inwati, Y Rao and M Singh. Thermodynamically induced in situ and tunable Cu plasmonic behaviour. Scientific Reports 2018; 8(1), 3006.
L Trinkler, D Dai, L Chang, M Chou, TY Wu, J Gabrusenoks, D Nilova, R Ruska, B Berzina and R Nedzinskas. Luminescence properties of epitaxial Cu2O thin films electrodeposited on metallic substrates and Cu2O single crystals. Materials 2023; 16(12), 4349.
M Zervos, I Paschos, P Savvidis, N Florini, K Koutsokostas, P Komninou, NN Lathiotakis, PM Levendis and S Marinakis. High crystal quality and purity Cu2O by consecutive in situ annealing and thermal oxidation of Cu under H2 and O2 at elevated temperatures. CrystEngComm 2025; 27(13), 1977-1985.
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