composites, congo red, dye, photocatalyst, titanium dioxide, zinc oxide


The development of new efficient photocatalysts is an important task for solving problems related to the purification of water and air from organic pollution. Composite materials based on ZnO and TiO2 exhibit high photocatalytic activity, which makes them promising for this application. In this work, we present the synthesis and study of the photocatalytic activity of ZnO/TiO2 composites obtained by the method of intermediate hydroxide deposition. The synthesis was carried out on the surface of Evonik P25 TiO2 with three different mass ratios of ZnO to TiO2: 1:3, 1:1, and 3:1. The resulting composites were studied by X-ray diffraction (XRD), spectroscopy to determine the optical band gap, and subjected to photocatalytic decomposition under circulating conditions. It was confirmed by XRD that ZnO crystallizes in the wurtzite phase of hexagonal syngony, and TiO2 is contained in the form of two modifications: anatase and rutile. The effect of the mass ratio of ZnO to TiO2 on the optical band gap has been studied. The optical band gap of ZnO/TiO2 composites was determined using the Kubelka-Munk algorithm. For the composites (1)ZnO/TiO2 and (3)ZnO/TiO2, the bandgap was 3.22 eV, and the lowest value (2.99 eV) was obtained for the composite with an equal ratio of ZnO to TiO2 - (2)ZnO/TiO2. The photocatalytic activity of ZnO/TiO2 composites was studied under circulating conditions with congo red dye in the presence of four different composite weights: 0.2, 0.4, 0.6, and 2 g. The maximum efficiency of photocatalytic decomposition of the dye was observed for the composite with an equal ratio of ZnO to TiO2 at a dosage of 2 g of the composite per 0.075 g of dye. The synthesized ZnO/TiO2 composites exhibit high photocatalytic activity, which makes them promising materials for water and air purification from organic pollution. The optimum mass ratio of ZnO to TiO2 for the photocatalytic decomposition of congo red dye is 1:1.


Abebe, B.; Zereffa, E. A.; Tadesse, A.; Murthy, H. C. A. A Review on Enhancing the Antibacterial Activity of ZnO: Mechanism and Microscopic Investigation. Nanoscale Res. Lett. 2020, 15(1), 190.

Ahmed, M. A.; Abou-Gamra, Z. M.; ALshakhanbeh, M. A.; Medien, H. Control synthesis of metallic gold nanoparticles homogeneously distributed on hexagonal ZnO nanoparticles for photocatalytic degradation of methylene blue dye. Environ. Nanotechnology, Monit. Manag. 2019, 12, 100217.

Banerjee, S.; Gopal, J.; Muraleedharan, P.; Tyagi, A. K.; Raj, B. Physics and chemistry of photocatalytic titanium dioxide: Visualization of bactericidal activity using atomic force microscopy. Curr. Scien. 2006, 90, 1378–1383.

Dhanalakshmi, R.; Pandikumar, A.; Sujatha, K.; Gunasekaran, P. Photocatalytic and antimicrobial activities of functionalized silicate sol-gel embedded ZnO-TiO2 nanocomposite materials. Mater. Express. 2013, 3(4), 291–300.

El Mragui, A.; Daou, I.; Zegaoui, O. Influence of the preparation method and ZnO/(ZnO + TiO2) weight ratio on the physicochemical and photocatalytic properties of ZnO-TiO2 nanomaterials. Catal. Today. 2019, 321–322, 41–51.

Firdaus, C. M.; Shah Rizam, M. S. B.; Rusop, M.; Rahmatul Hidayah, S. Characterization of ZnO and ZnO: TiO2 thin films prepared by sol-gel spray-spin coating technique. Procedia Eng. 2012, 41, 1367–1373.

Georgakopoulos, T.; Todorova, N.; Pomoni, K.; Trapalis, C. On the transient photoconductivity behavior of sol-gel TiO2/ZnO composite thin films. J. Non-Cryst. Solids, 2015, 410, 135–141.

Hasnidawani, J. N.; Azlina, H. N.; Norita, H., Bonnia, N. N.; Ratim, S.; Ali, E. S. Synthesis of ZnO Nanostructures Using Sol-Gel Method. Proced. Chemistry. 2016, 19, 211–216.

Hutsul, K.; Stepanova, A.; Byts, O.; Ivanenko, I. Photocatalytic activity of ZnO under near-real conditions. Mater. Today: Proceedings. 2022, 62(15), 7654–7659.

Ivanenko, I.; Hutsul, K.; Fedenko, Y. Nanocomposite TiO2/ZnO for Dyes Photocatalytic Degradation. Proceedings of the 2021 IEEE 11th International Conference “Nanomaterials: Applications and Properties”, NAP 2021, 2021.

Lavand, A. B.; Malghe, Y. S. Synthesis, characterization and visible light photocatalytic activity of nitrogen-doped zinc oxide nanospheres. J. Asian Ceram. Soc. 2015, 3(3), 305–310.

Liu, Q.; Liu, E.; Li, J.; Qiu, Y.; Chen, R. Rapid ultrasonic-microwave assisted synthesis of spindle-like Ag/ZnO nanostructures and their enhanced visible-light photocatalytic and antibacterial activities. Catal. Today. 2020, 339, 391–402.

Moradi, S.; Aberoomand-Azar, P.; Raeis-Farshid, S.; Abedini-Khorrami, S.; Givianrad, M. H. The effect of different molar ratios of ZnO on characterization and photocatalytic activity of TiO2/ZnO nanocomposite. J. Saudi Chem. Soc. 2016, 20(4), 373–378.

Phuruangrat, A.; Siri, S.; Wadbua, P.; Thongtem, S.; Thongtem, T. Microwave-assisted synthesis, photocatalysis and antibacterial activity of Ag nanoparticles supported on ZnO flowers. J. Phys. Chem. Solids. 2019, 126, 170–177.

Qi, K.; Xing, X.; Zada, A.; Li, M.; Wang, Q.; Liu, S.; Lin, H., Wang, G. Transition metal doped ZnO nanoparticles with enhanced photocatalytic and antibacterial performances: Experimental and DFT studies. Ceram. Int. 2020, 46(2), 1494–1502.

Raza, W.; Faisal, S. M.; Owais, M.; Bahnemann, D.; Muneer, M. Facile fabrication of highly efficient modified ZnO photocatalyst with enhanced photocatalytic, antibacterial and anticancer activity. RSC Adv. 2016, 6(82), 78335–78350.

Samadi, M.; Zirak, M.; Naseri, A.; Khorashadizade, E.; Moshfegh, A. Z. Recent progress on doped ZnO nanostructures for visible-light photocatalysis. Thin Solid Films. 2016, 605, 2–19.

Singh, J.; Soni, R. K. Controlled synthesis of CuO decorated defect enriched ZnO nanoflakes for improved sunlight-induced photocatalytic degradation of organic pollutants. Appl. Surf. Science. 2020, 521, 146–420.

Siuleiman, S. A.; Raichev, D. V.; Bojinova, A. S.; Dimitrov, D. T.; & Papazova, K. I. Nanosized composite ZnO/TiO2 thin films for photocatalytic applications. Bulgarian Chem. Commun., 2013, 45(4), 649–654.

Swati, Verma, R.; Chauhan, A.; Shandilya, M.; Li, X.; Kumar, R.; Kulshrestha, S. Antimicrobial potential of ag-doped ZnO nanostructure synthesized by the green method using moringa oleifera extract. J. Environ. Chem. Eng. 2020, 8(3), 103730.

Tian, J.; Chen, L.; Yin, Y.; Wang, X.; Dai, J.; Zhu, Z.; Liu, X.; Wu, P. Photocatalyst of TiO2/ZnO nano composite film: Preparation, characterization, and photodegradation activity of methyl orange. Surf. Coating. Technol. 2009, 204(1–2), 205–214.

Zhan, J.; Zhang, W.; Wang, M.; Guan, W.; Yan, X.; Zhang, Q.; Wang, H.; Wang, Z.; Zhang, Y.; Zou, L. Fabrication, characterization and antibacterial properties of ZnO nanoparticles decorated electrospun polyacrylonitrile nanofibers membranes. Mater. Today Communications. 2022, 103958.

Zhao, L.; Xia, M.; Liu, Y.; Zheng, B.; Jiang, Q.; Lian, J. Structure and photocatalysis of TiO2/ZnO double-layer film prepared by pulsed laser deposition. Mater. Trans. 2012, 53(3), 463–568.