1
Sivas University of Science and Technology, Faculty of Engineering and Natural Sciences, Department of Metallurgical and Materials Engineering, Sivas
Abstract
In this study, a novel Fe-doped CdS@CQDs nanocomposite was successfully synthesized via a facile one-pot hydrothermal method for the photocatalytic degradation of Congo Red (CR) dye under visible light. Structural analyses confirmed the formation of hexagonal CdS nanocrystals (8.5-10.9 nm) coupled with amorphous carbon quantum dots (CQDs). The Fe-doped CdS@CQDs nanocomposite demonstrated significantly enhanced photocatalytic performance, achieving approximately 90% degradation of CR in 120 minutes, whereas pristine CQDs achieved only 45% under identical conditions. This superior activity is attributed to the synergistic effects of Fe-doping, which introduces defect states that promote charge separation, and CQDs, which improve light harvesting and electron transport. Kinetic analysis revealed a pseudo-first-order reaction mechanism and a substantially lower activation energy for the Fe-doped CdS@CQDs (16.2 kJmol⁻¹) compared to CQDs (24.8 kJmol⁻¹). These findings highlight the potential of Fe-doped CdS@CQDs as a highly efficient and promising photocatalyst for treating dye-contaminated wastewater.
Keywords
Carbon quantum dots,Fe-doped CdS,photocatalysis,congo red degradation,activation energy
How to Cite
OĞUZ, T. (2025). Efficient Congo Red Photodegradation via Fe-Doped CdS@Carbon Quantum Dots under Visible Light Irradiation. MAS Journal of Applied Sciences, 10(4), 704–716. https://doi.org/10.5281/zenodo.17793887
📄Akinwunmi, O.O., Egharevba, G.O., Ajayi, E.O.B., 2014. Synthesis and characterization of CdS, ZnS and CdZnS nanoparticles embedded in polystyrene. Journal of Modern Physics, 5(5): 257–266.
📄Alharbi, F.K., Aissa, M.A. Ben, Al-Awaji, N., Younis, A.M., Alshahrani, A.A., Modwi, A., 2025. Green fabrication of magnesium oxide nano-sorbent using Gum Arabic for Congo red dye and cadmium ions elimination. Water, Air, & Soil Pollution, 236(11): 693.
📄Ammar, S.H., Shafi, R.F., Ali, A.D., 2020. A novel airlift photocatalytic fuel cell (APFC) with immobilized CdS coated zerovalent iron (Fe@CdS) and g-C3N4 photocatalysts film as photoanode for power generation and organics degradation. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 602: 125164.
📄Arabacı, B., Bakır, R., Orak, C., Yüksel, A., 2025. Predictive modeling of photocatalytic hydrogen production: integrating experimental insights with machine learning on Fe/g-C3N4 catalysts. Industrial & Engineering Chemistry Research, 64(10): 5184-5199.
📄Bakır, R., Orak, C., 2024. Stacked machine learning approach for predicting evolved hydrogen from sugar industry wastewater. International Journal of Hydrogen Energy, 85: 75–87.
📄Bakır, R., Orak, C., Horoz, S., 2025. Enhancing photocatalytic degradation of hazardous pollutants with green-synthesized catalysts: A machine learning approach. Journal of Environmental Management, 385: 125695.
📄Bakır, R., Orak, C., Yüksel, A., 2024a. A machine learning ensemble approach for predicting solar-sensitive hybrid photocatalysts on hydrogen evolution. Physica Scripta, 99(7): 076015.
📄Bakır, R., Orak, C., Yüksel, A., 2024b. Optimizing hydrogen evolution prediction: A unified approach using random forests, light GBM, and Bagging Regressor ensemble model. International Journal of Hydrogen Energy, 67:101-110.
📄Balnan, İ., Horoz, S., Kaya, K.K., Orak, C., 2025. Europium incorporation in ZnS and CDS: structural modifications, optical transitions, and photocatalytic efficiency. Journal of the Australian Ceramic Society, 1-13.
📄Batur, E., Baytar, O., Horoz, S., Şahin, Ö., Kutluay, S., 2022. Enhancement in incident photon-to-current conversion efficiency of manganese-decorated activated carbon-supported cadmium sulfide nanocomposite. Journal of Materials Science: Materials in Electronics, 33(20): 6286–16296.
📄Batur, E., Kutluay, S., Baytar, O., Şahin, Ö., Horoz, S., 2023. Superior incident photon-to-current conversion efficiency of Mo-doped activated carbon supported CdS-sensitized solar cells. Environmental Science and Pollution Research International, 30(8): 19766–19775.
📄Batur, E., Şahin, Ö., Baytar, O., Horoz, S., Kutluay, S., 2023. High solar cell efficiency of lanthanum-alloyed activated carbon–supported cadmium sulfide as a promising semiconductor nanomaterial. Journal of the Australian Ceramic Society, 59(1): 9–18.
📄Baytar, O., Sahin, O., Kilicvuran, H., Horoz, S., 2018a. Synthesis, structural, optical and photocatalytic properties of Fe-alloyed CdZnS nanoparticles. Journal of Materials Science: Materials in Electronics, 29(6): 4564–4568.
📄Ca, N.X., Bau, N.Q., Phan, T.L., Lien, V.T. K., Lieu, N.T.T., Nghia, N.X., 2017. Temperature-dependent photoluminescent and raman studies on type-II CdS/ZnSe core/shell and CdS/CdZnS-ZnCdSe/ZnSe core/intermediate/shell nanoparticles. Journal of Alloys and Compounds, 697:401–408.
📄Dervishi, E., Ji, Z., Htoon, H., Sykora, M., Doorn, S.K., 2019. Raman spectroscopy of bottom-up synthesized graphene quantum dots: size and structure dependence. Nanoscale, 11(35): 16571–16581.
📄Doğan, V., Yılmaz, S., Tomakin, M., Töreli, S.B., Polat, İ., Bacaksız, E., 2024. Improving photovoltaic characteristics of CdS-based hybrid solar cells through Mn incorporation. Journal of Photochemistry and Photobiology A: Chemistry, 453: 115678.
📄Ganguly, A., Srivastava, V.M., 2020. Synthesis and characterization of Fe doped CdS quantum dot. IEEE VLSI Device Circuit and System, 1–4.
📄Haste, Z.Ö., Horoz, S., Orak, C., Biçer, E., 2024. Green-Synthesized SnO2 derived from kombucha tea and assessment of its photocatalytic activity for the degradation of procion red MX-5B. Chemistry Select, 9(43): e202403264.
📄Horoz, S., 2017. Investigation of semiconductor quantum dots for quantum sensitized solar cells (QDSSCs). Cumhuriyet Science Journal, 38(4): 121–129.
📄Horoz, S., Orak, C., Biçer, E., 2025. Green synthesis of ZnO and Ni-doped ZnO from okra stalks for the photocatalytic degradation of Procion Red MX-5B. International Journal of Phytoremediation, 27(2): 206-214.
📄Horoz, S., Sahin, O., 2017a. Investigations of structural, optical, and photovoltaic properties of Fe-alloyed ZnS quantum dots. Journal of Materials Science: Materials in Electronics, 28(13): 9559–9565.
📄Horoz, S., Sahin, O., 2017b. Synthesis, characterization and photovoltaic properties of Mn-doped Sb2S3 thin film. Materials Science- Poland, 35(4): 861–867.
📄Horoz, S., Sahin, O., Ekinci, A., 2018. Synthesis of Fe alloyed PbS thin films and investigation of their photovoltaic properties. Journal of Materials Science: Materials in Electronics, 29(16):13442–13448.
📄Karakaş, D.E., Horoz, S., Durap, F., Orak, C., Kaya, M., 2025. Integrated catalytic and energy storage performance of grass waste derived ni-based catalyst. Arabian Journal for Science and Engineering, 50(6): 4209-4221.
📄Kaya, K.K., Orak, C., Horoz, S., 2025. PVDF@SnO₂ Composite Thin Films: A Durable and Efficient Photocatalyst for Wastewater Treatment. Waste and Biomass Valorization, 1-11.
📄Kostić, R., Romčević, N., 2004. Raman spectroscopy of CdS nanoparticles. Physica Status Solidi (c), 1(11): 2646-2649.
📄Liu, X., Jiang, Y., Fu, F., Guo, W., Huang, W., Li, L., 2013. Facile synthesis of high-quality ZnS, CdS, CdZnS, and CdZnS/ZnS core/shell quantum dots: characterization and diffusion mechanism. Materials Science in Semiconductor Processing, 16(6): 1723–1729.
📄Ma, H., Guan, L., Chen, M., Zhang, Y., Wu, Y., Liu, Z., Wang, D., Wang, F., Li, X., 2023. Synthesis and enhancement of carbon quantum dots from Mopan persimmons for Fe3+ sensing and anti-counterfeiting applications. Chemical Engineering Journal, 453: 139906.
📄Maran, M.A., Zheng, A.L.T., Tan, H.Y., Sarbini, S.R., Tan, K.B., Boonyuen, S., Wong, K.K.S., Chung, E.L.T., Lease, J., Andou, Y., 2025. Assessing the photocatalytic performance of hydrothermally synthesized fe-doped BiVO4 under low-intensity UV irradiation. Arabian Journal for Science and Engineering, 1-19.
📄Mehrabanpour, N., Nezamzadeh-Ejhieh, A., Ghattavi, S., 2023. Cefotaxime degradation by the coupled binary CdS-PbS: characterization and the photocatalytic process kinetics. Environmental Science and Pollution Research, 30(12): 33725–33736.
📄Mehrabanpour, N., Nezamzadeh-Ejhieh, A., Ghattavi, S., Ershadi, A., 2023. A magnetically separable clinoptilolite supported CdS-PbS photocatalyst: Characterization and photocatalytic activity toward cefotaxime. Applied Surface Science, 614:156252.
📄Mekidiche, M., Khaldi, K., Lerari-Zinai, D., Bachari, K., 2025. Montmorillonite-supported Cu-tripeptide complex for efficient Congo red degradation. Materials Chemistry and Physics, 339: 130640.
📄Mmelesi, O.K., Mguni, L.L., Li, F., Nkosi, B., Liu, X., 2024. Recent development in fluorescent carbon quantum dots-based photocatalysts for water and energy applications. Materials Science in Semiconductor Processing, 181:108661.
📄M Naziruddin Khan Abdullah, A., M.A. Majeed, K., Muhammad Ali, S., 2020. Metals doped CdS quantum dots: structural, optical and photocatalytic properties under visible light irradiation. International Journal of Metallurgy and Metal Physics, 5(1): 049.
📄Moslem, S.S., El komy, G.M., El-Khawas, E.H., Azab, A.A., 2025. Effect of Fe doping on structural, optical and magnetic properties of CdS quantum dots. Physica Scripta, 100(3): 035916.
📄Nair, P.S., Radhakrishnan, T., Revaprasadu, N., Kolawole, G., O’Brien, P., 2002. Cadmium ethylxanthate: A novel single-source precursor for the preparation of CdS nanoparticles. Journal of Materials Chemistry, 12(9): 2722–2725.
📄Nan, Z., Hao, C., Zhang, X., Liu, H., Sun, R., 2020. Carbon quantum dots (CQDs) modified ZnO/CdS nanoparticles based fluorescence sensor for highly selective and sensitive detection of Fe (III). Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 228: 117717.
📄Nar, S., Şahin, Ö., Horoz, S., 2019. Fabrication of Pure Sb2S3 and Fe (2.5%): Sb2S3 Thin Films and Investigation Their Properties. Journal of Inorganic and Organometallic Polymers and Materials, 29(4): 1331–1336.
📄Onat, E., Horoz, S., Şahin, Ö., İzgi, M.S., 2024. Revolutionary carbon quantum dot supported-Co catalyst for record-breaking hydrogen production rate. Journal of the Australian Ceramic Society, 61: 117-126.
📄Onat, E., Şahin, Ö., İzgi, M.S., Horoz, S., 2021. An efficient synergistic Co@CQDs catalyst for hydrogen production from the hydrolysis of NH3BH3. Journal of Materials Science: Materials in Electronics, 32(23): 27251–27259.
📄Orak, C., 2024a. Enhanced degradation of procion red MX-5B using Fe-doped corn cob ash and Fe-doped g-C3N4. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 46(1): 14244–14258.
📄Orak, C., 2024b. Treatment of sugar industry wastewater via fenton oxidation with zero-valent iron. Cumhuriyet Science Journal, 45(1): 100–104.
📄Orak, C., Atalay, S., Ersöz, G., 2016. Degradation of ethylparaben using photo-Fenton-like oxidation over BiFeO3. Anadolu University Journal of Science and Technology A-Applied Sciences and Engineering, 17(5): 915.
📄Orak, C., Ersöz, G., 2024. Heterogeneous photo-fenton-like degradation of oxytetracycline containing wastewater. Journal of Advanced Research in Natural and Applied Sciences, 10(1): 182–189.
📄Orak, C., Horoz, S.,2025. Multifunctional α-MnO2 and Cr/Ni-Doped α-MnO2: a green approach to dye degradation and energy storage. Ionics, 31: 6483–6493.
📄Orak, C., Oğuz, T., Horoz, S., 2024. Facile synthesis of Mn-doped CdS nanoparticles on carbon quantum dots: towards efficient photocatalysis. Journal of the Australian Ceramic Society, 5: 1657-1667.
📄Orak, C., Yüksel, A., 2021a. Graphene-supported LaFeO3 for photocatalytic hydrogen energy production. International Journal of Energy Research, 45(9): 12898–12914.
📄Orak, C., Yüksel, A., 2021b. Photocatalytic hydrogen energy evolution from sugar beet wastewater. Chemistry Select, 6(43): 12266–12275.
📄Orak, C., Yüksel, A., 2022a. Box-behnken design for hydrogen evolution from sugar industry wastewater using solar-driven hybrid catalysts. ACS Omega, 7(46): 42489–42498.
📄Orak, C., Yüksel, A., 2022b. Comparison of photocatalytic performances of solar-driven hybrid catalysts for hydrogen energy evolution from 1,8–Diazabicyclo[5.4.0]undec-7-ene (DBU) solution. International Journal of Hydrogen Energy, 47(14): 8841–8857.
📄Quintanilla-Villanueva, G.E., Sicardi-Segade, A., Luna-Moreno, D., Núñez-Salas, R.E., Villarreal-Chiu, J.F., Rodríguez-Delgado, M.M., 2025. Recent Advances in Congo Red Degradation by TiO2-Based Photocatalysts Under Visible Light. Catalysts, 15(3).
📄Tungare, K., Bhori, M., Racherla, K.S., Sawant, S., 2020. Synthesis, characterization and biocompatibility studies of carbon quantum dots from Phoenix dactylifera. 3 Biotech, 10(12): 540.
📄Xu, S., Wang, Y., Wu, Y., Li, M., 2024. Nitrogen and sulfur co-doped coal-based carbon quantum dots enhance the photocatalytic hydrogen evolution of Co-Fe-P derived from MOF. Surfaces and Interfaces, 44: 103576.
📄Yang, K., Yang, Z., Zhang, C., Gu, Y., Wei, J., Li, Z., Ma, C., Yang, X., Song, K., Li, Y., Fang, Q., Zhou, J., 2021. Recent advances in CdS-based photocatalysts for CO2 photocatalytic conversion. Chemical Engineering Journal, 418: 129344.
📄Zheng, Z., Han, F., Xing, B., Han, X., Li, B., 2022. Synthesis of Fe3O4@CdS@CQDs ternary core–shell heterostructures as a magnetically recoverable photocatalyst for selective alcohol oxidation coupled with H2O2 production. Journal of Colloid and Interface Science, 624: 60–470.
