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Article

Photocatalytic Properties of Sol–Gel Films Influenced by Aging Time for Cefuroxime Decomposition

by
Nina Kaneva
Laboratory of Nanoparticle Science and Technology, Department of General and Inorganic Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier Blvd., 1164 Sofia, Bulgaria
Crystals 2026, 16(1), 8; https://doi.org/10.3390/cryst16010008 (registering DOI)
Submission received: 9 December 2025 / Revised: 21 December 2025 / Accepted: 22 December 2025 / Published: 23 December 2025
(This article belongs to the Special Issue Functional Thin Films: Growth, Characterization, and Applications)
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Abstract

Dip-coating and sol–gel techniques are used to apply ZnO sol–gel films to glass substrates. The primary ingredient used to produce the film is zinc acetate dihydrate. The ZnO sample is prepared for 0, 1, 3, 5, 10, 15, and 30 days. To deposit nanocrystalline thin films, several gels are used. The films’ structural and photocatalytic properties are examined in relation to the ZnO solid’s aging time. UV–vis spectroscopy is used to evaluate the catalytic degradation of the antibiotic cefuroxime (CFX) in tap and distilled water, taking into account the initial solution’s aging duration. Every experiment is carried out under ultraviolet light illumination. These findings demonstrate that ZnO’s photocatalytic activity generally prolongs the initial solution. When compared to freshly prepared films, films made from a ZnO sample for 30 days showed the highest photocatalytic degradation of the medication under UV light. Overall, the photocatalytic activity of ZnO is increased by increasing the aging time of the starting solution. All samples and the photocatalytic test findings are reproducible.

1. Introduction

In recent years, pharmaceutical compounds, even at low concentrations, have been discovered in wastewater effluents, posing environmental challenges to aquatic and human life [1]. Many drugs are commonly used as antibiotics, antiseptics, disinfectants, and anti-inflammatory drugs [2]. Cefuroxime is a popular cephalosporin antibiotic and anti-pyretic drug that is used all over the world [3]. The fact that Axetine, the commercial name for the medication containing Cefuroxime, is frequently found in the environment, especially in aquatic ecosystems, suggests that it is not a completely safe medication. Its high production levels and widespread use can have harmful effects [4]. The antibiotic may increase liver enzymes, decrease platelets (cells that aid in blood clotting), and increase a type of white blood cell known as eosinophilia [4,5,6,7]. Considering these factoors, suggesting a successful treatment strategy that could transform Cefuroxime into a non-toxic product is critical. Numerous sophisticated oxidation techniques are used to eliminate such compounds, including heterogeneous photocatalysis [8], UV oxidation [9], ozonation [9], and sonolysis [10].
The concentration of pollutants is decreased in contaminated air and water by pho-tocatalytic processes that use UV-irradiated inorganic oxides. Photocatalytic degradation in solutions exposed to UV light is a useful technique for treating drug containing wastewater. Appropriate photocatalysts, such as ZnO [11,12,13,14], In2O3 [15,16], SnO2 [17,18], and TiO2 [19,20,21,22], support this process. Because of their optical and transport characteristics, these materials are excellent choices for contemporary applications when used in thin-film form. The most well-known and chemically stable of these oxides is zinc oxide, which is widely applied as a coating in optical thin films. Furthermore, ZnO attracted a lot of attention because of its superior catalytic properties. The thin films and their photocatalytic properties have not received much attention, despite the material’s importance in photocatalytic processes. Although the effects of sol–gel [23,24,25], chemical vapor deposition [26,27], thermal evaporation [28,29,30,31], oxidation [32], and nodizing [33] for producing ZnO have been documented, the effects of sol–gel on the characteristics of Zn for photocatalytic drug degradation are still poorly understood. As the sol ages, some of its properties change. Examining the effect of solving time can therefore have a significant impact on the physical and photocatalytic characteristics of the films.
This study prepares ZnO catalysts onto glass using the dip-coating, sol–gel techniques, and examines the impact of ZnO starting sol aging times (0, 1, 3, 5, 10, 15, and 30 days) on the films’ structure and photocatalytic characteristics. Cefuroxime is degraded in tap and distilled water using the ZnO thin films that are deposited. Ultraviolet light is used to illuminate photocatalytic tests. According to our earlier research, there will not be any precipitation for up to a month and the sol is stable. In each of the three cycles of the photocatalytic experiments, a fresh antiobiotic solution with the same starting concentration is used. Every test is repeatable.

2. Materials and Methods

Zinc acatate dihydrate (Zn(CH3COO)2·2H2O, ≥99.5%, Fluka, Buchs, Switzerland), 2methoxyethanol (C3H8O2, ≥99.5%, Fluka, Buchs, Switzerland), and monoethanolamine (C2H7NO, ≥99.0%, Sigma Aldrich, Bulington, MA, USA) were the substances that are used to create ZnO sol–gel films. The glass slides (76 mm by 26 mm) that were used as ZnO film substrates came from ISOLAB, Wertheim, Germany. The antibiotic solutions were made with distilled water.
For all catalytic assays, the commercial medication Cefuroxime (C20H22N4O10S, λmax = 290 nm, 99.0%) was selected as the model contaminant. To demonstrate how CFX degrades in the presence of various pollutants, precisely as it does in natural water systems, photocatalytic tests were conducted using tap and distilled water.
The dissolved salt levels in Sofia, Bulgaria’s tap water were lower than those in other tap water samples (c(Na+) = < 5.01 mg/L; c(Ca2+) = < 10.74 mg/L; c(Mn2+) = < 11 μg/L; c(Fe2+) = < 123 μg/L; c(Cl−) = 5 mg/L; c(SO42−) = 11 mg/L; c(NO3−) = 0.94 mg/L). When the mean value of the indicator “total hardness” was less than 0.75 mgeq/L, Sofia’s water delivery system was classified as “freshwater.” In compliance with European rules, the naturally clean mountainous water from the “Beli Iskar” dam had to be filtered at a treatment station. Bacteria and dissolved organic compounds were removed using a disinfection process.
ZnO sol–gel films were deposited onto glass substrates using the dip coating method, which involved a 0.9 cm/min withdrawal speed and 35 s immersion time in the solution. The initial precursor, solvent, and stabilizer were zinc acetate dehydrate, 2-methoxyethanol, and monoethanolamine (MEA). 2-methoxyethanol was preferred because of its low carbon number and strong inorganic salt-dissolving capabilities [34,35]. The solubility of zinc acetate in the chosen solvent is restricted. To finish the dissolution and create a stable solution, substances such as mono- and/or tri-ethanolamine are helpful [36]. MEA was introduced to create a transparent and stable solution. The molar ratio of Zn2+ to MEA was maintained at 1.0. Zinc acetate was first dissolved in 2-methoxyethanol at ambient temperature and stirred for an hour at 60 °C. MEA was then gradually added to the solution. Ultimately, a homogeneous, transparent solution developed and held its stability for over four months. The foundation of sol–gel chemistry is the hydrolysis and condensation reaction that turns the molecular precursor into an oxide network [37]. The following is a summary of the complex reaction equations [38]:
C H 3 ― C O O ― Z n ― O O C ― C H 3 → [ C H 3 ― C O O ― Z n ] + + [ C H 3 C O O ] ―
H 2 N ― C H 2 ― C H 2 ― O H + [ C H 3 ― C O O ― Z n ] + → H O − C H 2 ― C H 2 ― N H 2 ― Z n ― O O C ― C H 3
The next reaction procedure can be expressed as a hydrolysis and dehydration polycondensation reaction:
H O − ( C H 2 ) 2 ― N H 2 ― Z n ― O O C ― C H 3 + H 2 O → H O − C H 2 ― C H 2 ― N H 2 ― Z n ― O H + C H 3 ― C O O H
H O − C H 2 ― C H 2 ― N H 2 ― Z n ― O H + H O − C H 2 ― C H 2 ― N H 2 ― Z n ― O H →   → H O − C H 2 ― C H 2 ― N H 2 ― Z n ― O ― Z n ― N H 2 ― C H 2 ― C H 2 ― O H + H 2 O
The sol’s ages were 0, 1, 3, 5, 10, 15, and 30 days, in that order. Following a thorough cleaning and drying process, zinc oxide samples were deposited onto glass substrates by the dip-coating method. The glass substrate was dipped in the precursor solution and pulled out at a rate of 0.9 cm/min to create the glass films at room temperature. Higher withdrawal rates produced lower-quality films, according to experiments. Although this deposition technique is straightforward and affordable, it necessitates soluble chemicals. Five coatings with varying aging times were applied to the films. Each subsequent coating was followed by 30 min of drying at 80 °C. The final gel films were annealed for an hour at 500 °C to produce the ZnO films for testing. The surface morphology of ZnO thin films at various aging durations was examined using a scanning electron microscope (SEM, JEOL JSM-5510, Tokyo, Japan) with an acceleration voltage of 10 kV. Before being seen, the examined samples were coated with gold using a JFC-1200 fine coater (Tokyo, Japan). The X-ray diffraction (XRD) diffractograms were recorded at room temperature using a powder diffractometer (Karlsruhe, Germany) (Siemens D500 with CuKα reflection within a 2θ range of 30–70 degrees at a step size of 0.05 and a counting duration of 2 s/step). Scherrer’s equation was used to estimate the average size of crystallites [39]. The catalytic decomposition of Cefuroxime in tap and distilled water was used to assess the samples’ effectiveness. A standard pharmaceutical solution consists of 0.5 g of the drug dissolved in 0.5 L of water. Pure working solutions (Cefuroxime, CFX) with a 50 ppm concentration were created by dilution and membrane filtration. A 36-watt ultraviolet lamp with a wavelength of 315–400 nm provided the light. The sample was placed horizontally in a 200 mL glass reactor with a magnetic stirrer that was rotated at 500 rpm and controlled by a stroboscope as part of a standard test. Every UV-based photocatalysis experiment was conducted at room temperature, or 23 ± 2 °C. The adsorption–desorption equilibrium between the photocatalyst and Cefuroxime was achieved by shaking the drug solution in the dark for fifteen minutes prior to exposing it to illumination. Two milliliters of the treated solution were removed at regular intervals. A UV–vis spectrophotometer (Evolution 300 Thermo Scientific spectrophotometer; Madison, WI, USA) was used to measure the absorbance value at 290 nm in order to determine the relative concentration of the antibiotic in the treated solution. For usage in tests using distilled and tap water, seven series of nanostructured ZnO films were made with five coatings and obtained at different aging durations of the starting solution (0, 1, 3, 5, 10, 15, and 30 days). The photocatalysts’ stability was also evaluated.

3. Results

3.1. Structure Evaluation of Sol–Gel ZnO Films

Scanning electron microscopy is used to describe the morphology of seven different types of ZnO thin films (Figure 1). The surface modifications of the films are readily visible in these micrographs. The surface morphology of the ZnO thin film formed from gel aged for 0 days (ZnO/0 d) was extremely smooth and covered in round grains, as shown in Figure 1a. In certain applications, producing extremely smooth surfaces is crucial, but not in photocatalysis. As a result, the movies were the least active. The surface morphology of another zinc oxide layer, which was not smooth, is shown in Figure 1b. The ZnO films (ZnO sol lasted 1 day, ZnO/1 d) had a structure that resembled ganglia under a scanning electron microscope. The morphology of the wrinkles was consistent. Their thickness, size, and shape were influenced by how long the original solution aged. As ZnO sol aged longer, the ganglia-like hills (Figure 1b–g) became bigger, more dispersed, and had branches at the ends. There were more wrinkles, and the morphology was consistent. The ganglia-like structure appeared to be reproducible regardless of annealing and film decomposition conditions. The sol aging process led to the formation of films with improved surface area and a more favorable pore distribution, which increased the number of active sites for catalytic reactions. Through controlled aging and subsequent thermal treatment, surface stabilization could be achieved (e.g., by the formation of HO-zinc oxide centers), which reduced the undesirable degradation of characteristics during subsequent use [40,41]. This was also supported by the specific surface area (BET) values (ZnO/0 d had 10.7 m2/g, ZnO/15 d had 13.8 m2/g, and ZnO/30 d had 16.3 m2/g). The aging process of the sol caused a slight increase in the surface area of ZnO, indicating an increase in the number of surface sites. This was probably due to the change in surface morphology resulting from the formation of more active sites.
Figure 2b shows the XRD data of ZnO films from solutions aged for 0 and 10 days. The films showed a diffraction peak at around 34.4°, which was the reflection of the (002) plane of ZnO with a wurtzite structure. Accordingly, every sample had a hexagonal wurtzite structure and was oriented preferentially along the c-axis, which runs parallel to the substrate’s surface (PDF #96-230-0117). This outcome was verified [42]. According to Fathollahi and Amini, sol aging may encourage additional active group condensation and zinc species aggregation in the solution, which could result in a notable improvement in the zinc oxide (002) reflection [42]. Our results, together with those of Fathollahi and Amini [42], indicate that sol aging can enhance the degree of preferred crystal orientation along the c-axis without altering the orientation of crystal development.
The (002) direction was the preferred orientation of nanostructured ZnO thin films that were produced at 500 °C from a solution that had been aged for less than 10 days. Instead, the ZnO thin films that were deposited from solutions that had been aged for more than 10 days showed a preference for orientation along the (101) direction. These results are comparable to those of refs. [43,44], who used spray pyrolysis to create ZnO thin films and found that the orientation of crystal formation is significantly influenced by the stirring time of the solution. The average crystallite sizes of the ZnO/0 d, ZnO/10 d, and ZnO/30 d films were 23, 19, and 16 nm, respectively (Table 1). These findings offer additional proof that longer aging durations are associated with smaller crystallites [45,46]. The XRD data demonstrate that the ZnO sol’s aging time does not significantly alter the crystal size. The average crystallite size decreased, whereas the crystalline lattice parameters barely changed (Table 1). For instance, samples retained their hexagonal wurtzite structure, according to lattice parameters for thin films. When compared to ZnO derived from unaged sol, the microstrain in ZnO/10 d films (a.u.) and ZnO/30 d films (a.u.) exhibited a minor tensile strain magnitude.
Regardless of the differences in deposition methods, all of the studies show that the aging period of the starting solution influences the architectures and photocatalytic activity of ZnO thin films. In terms of the sol–gel process, our findings indicate that a ZnO sol aged for 30 days is the optimum for developing outstanding ZnO thin films that decompose Cefuroxime in tap and distilled water when exposed to UV light.
ZnO was detected by FTIR spectroscopy studies, which produced absorbance at roughly 450 cm−1 (Figure 3). After annealing, all organics and O-H groups were eliminated, and the sample weight decreased by around 13% as a result of a dehydration process. The absence of absorbance bands within the interval 500–3000 cm−1 indicated that there was no detectable organics.
UV–vis absorption spectroscopy was used to examine the semiconductors’ optical characteristics. The ZnO/0 d film had an absorption band in the UV region at about 362 nm, as seen in Figure 4a. The ZnO/30 d sample, on the other hand, displayed a minor shift in the absorbance band (λmax = 364 nm) due to the sol’s aging duration. The transformation of the molecular precursor into oxide networks was the cause of this interaction. UV–visible absorption spectroscopy is a common approach for investigating materials’ optical properties. Figure 4b depicts the numbers obtained from the Kubelka–Munk extrapolation of the gel’s energy band gap. The calculated band gaps for the films were ZnO/0 d (3.23 eV), ZnO/15 d (3.19 eV), and ZnO/30 d (3.17 eV). It is worth noting that the band gap values decreased as the sol aged. Microstrain may increase in tandem with a decrease in the band gap (EG). A prior study discovered that strain could alter the interatomic spacing of semiconductors, influencing the energy gap value [47]. Our findings are consistent with other researchers’ findings that the optical band gap decreases as tensile strength increases [48,49]. Furthermore, Rao et al. [50] demonstrated that roughness had little effect on the optical properties of ZnO films. The band gap in ZnO film was not much influenced by roughness.
Photoluminescence emission spectra were used to study the effectiveness of charge carrier trapping, charge transfer, and surface imperfections. Furthermore, the produced metal oxide semiconducting material’s photo-induced electron–hole pair behavior was shown by PL spectra. Photoluminescence was carried out at room temperature using an excitation wavelength of 325 nm (UV-A light), as seen in the Figure 5. The electron–hole pairs recombined following photon emission during photocatalysis due to the reverse radiative deactivation of zinc species.
The PL spectra showed that the ZnO sol’s peak intensity decreased with aging time. The ZnO valence and conduction bands thus developed defect states [51]. By lowering the rate of electron–hole pair recombination, the photocatalyst made it possible to degrade a variety of contaminants, including Cefuroxime. Charge transfer from zinc ions to oxygen vacancies is represented by the emission peak at 447 nm in Figure 6 [52]. The defect electronic states brought on by oxygen vacancies in ZnO are responsible for the stronger peaks at 496 and 520 nm, which indicate green emission. Charge carriers trapped around surface oxygen vacancies are the cause of photoluminescence emission spectra seen in the green region, between 500 and 550 nm [53,54]. Notably, the intensity of ZnO’s PL characteristic reduced as the sol aged. This indicates that the ZnO/30 d film had the maximum photocatalytic activity by preventing photogenerated electron–hole pair recombination.

3.2. Photocatalytic Activity of Sol–Gel ZnO Films—Effect of Sol Aging Time

We examined the photocatalytic efficiency of Cefuroxime, a commonly produced cephalosporin antibiotic. The distilled water solution of xetine was initially left in the dark for 50 min to ensure the drug’s adsorption and desorption on the samples. Figure 6 illustrates how ZnO films made of various materials with varying drying times break down antibiotics when exposed to UV light.
The calculated k values of sol–gel films, as well as the change in ln(C/C0) with irradiation time, are shown in Figure 6b. ZnO/30 d had a k value that was 3.07 times greater than ZnO/0 d in terms of xetine degradation. As a result, ZnO/30 d showed higher photocatalytic activity than ZnO/0 d. Figure 6c shows the proportion of Axetine degradation, which clarifies the constant values. Because photogenerated electrons and holes are known to stimulate the photocatalytic reaction, the response and transfer of photogenerated electron–hole pairs often depend on the photocatalytic activity of a catalyst. Cefuroxime degradation was tracked at 500 rpm using UV–vis spectroscopy, which was utilized to observe the absorption maximum at 290 nm. To determine the activity of the three types of ZnO films during the photocatalytic process, spectral changes in the degradation of the cephalosporin antibiotic were examined. The UV–vis spectrum and the percentage of axetine degradation are shown in Figure 6d.
These graphs show that Cefuroxime breaks down more quickly as the aged solution rises. Our findings indicate that films with a higher level of surface roughness degraded Cefuroxime more effectively than films with a lower level of surface roughness. As demonstrated by Prile et al. [55], the porous surface increases the active surface sites, which enhances the films’ catalytic efficiency. Based on this, we can deduce that the formation of spatial structures increases photocatalytic activity by extending the exposed area and improving the lifetime of the photogenerated holes. Higher constant values indicate a greater degradation of CFX because UV light can stimulate catalyst electrons and oxidize the organic pollutant (Table 2).

3.3. Photocatalytic Activity of Sol–Sel ZnO Films—Tap Water’s Impact

Cefuroxime breakdown in tap water showed a consistent pattern: ZnO films deposited from a solution that was left for 30 days showed the highest photocatalytic activity, as shown by the largest k value (Figure 7). It should be noted that a variety of factors, such as surface area, might impact photocatalytic efficiency. Higher surface porosity, for example, increases the quantity of active surface sites, which improves catalytic performance. A rougher surface is more effective than a smooth one at degrading drugs. The growth and orientation of nanorods, which offer a higher photocatalytic efficiency because of their large surface area and special porous surface structure, may therefore account for the highest rate.
Cefuroxime degradation in distilled water is lower than in drinking water for all sol–gel ZnO film types. The variations in pH provide an explanation for this observation. pH controls the photocatalytic process, as we know. The pH values of tap water and distilled water differ somewhat (pHtap = 7.39 and pHdistilled = 6.8). Ramsamy et al. [56] looked into the impact of pH and found that the rate of drug degradation increased as the pH rose from 4 to 8.5. The maximum Cefuroxime rate constant of 0.7853 h−1 is recorded when the pH of the drinking water is 7.39. The ratio constant (k) falls to 0.248 h−1 with even a slight change in pH. According to prior research, our findings are consistent [57].

3.4. Photocatalytic Activity of Sol–Gel ZnO Films—Effect of Initial Concentration of Drug

Increasing the initial drug concentration usually leads to a decrease in the efficiency and rate of photocatalytic degradation. This is shown in Figure 8. The trend is that with increasing antibiotic concentration (3, 5, and 10 ppm), the catalytic activity decreases in the films [58].
This effect is explained by several main factors, including (i) saturation of the active sites. At higher concentrations, more drug molecules adsorb onto the surface of the photocatalyst. This leads to saturation of the available active sites, due to which the free radicals required for degradation become insufficient to process all the molecules. (ii) Limited light penetration (screening effect) is another main factor. Higher solute concentration can lead to the absorption of more photons by the liquid itself before they reach the catalyst surface. As a result, less light reaches the catalyst, which reduces the generation of electron-hole pairs and, consequently, the reaction rate [59].

3.5. Photocatalytic Efficiency of Sol–Gel ZnO Films—Effect of Photostability

For photocatalysts to be used in environmental applications, they must have high photocatalytic properties throughout time. Therefore, photocatalytic tests were conducted under UV light to demonstrate the cycling stability of several types of catalysts for the degradation of cefuroxime in distilled and tap water. Figure 9 displays the findings of research on film regeneration and repurposing, demonstrating that catalytic quality steadily decreases with each cycle. The photocatalytic breakdown of xetine by the catalysts decreased by approximately 2% in both types of water after three cycles. Nevertheless, following three experimental cycles, the nanostructures derived from the 30-day-aged sol showed enhanced catalytic activity.

4. Conclusions

The sol–gel method, which uses zinc acetate dehydrate soaked in 2-methoxyethanol and monoethanolamine to examine the effects of sol aging time, produces nanostructured ZnO films. This straightforward and affordable technique produces smooth-surfaced samples from unstayed sol. This could be the result of insufficient stability in the produced sol, which causes uneven colloidal particle sizes and distribution. As a result, the as-synthesised sol is deposited as a relatively low-quality film. The ZnO thin films should be aged for 30 days to gradually improve their optical and structural qualities. The aging time of the starting solution has a major impact on how quickly Cefuroxime breaks down in tap and distilled water. The rate at which Cefuroxime degrades in distilled and tap water is significantly influenced by the aging period of the initial solution. ZnO thin films show promise for water-cleansing applications based on photocatalysis processes.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The author declares no conflicts of interest.

References

  1. Matheen, I.; Tajudeen, S.; Raza, A. Efficient photocatalytic degradation of cefuroxime and tetracycline antibiotics using a novel triazine based covalent organic framework grafted with Cu/CuO nanoparticles. Inorg. Chem. Commun. 2025, 181, 115262. [Google Scholar] [CrossRef]
  2. Naseem, A.; Alneghery, L.; Al-Zharani, M.; Nasr, F.; Jawad, S.; Umer, M.; Sayyed, R.; Ilyas, N. An insight into the impacts of pharmaceutical pollutants on the ecosystem and the potential role of bioremediation in mitigating pharmaceutical pollutants. Int. J. Pharm. 2025, 680, 125791. [Google Scholar] [CrossRef]
  3. Segal, N.; Leibovitz, E.; Dagan, R.; Leiberman, A. Acute otitis media-diagnosis and treatment in the era of antibiotic resistant organisms: Updated clinical practice guidelines. Int. J. Ped. Otorhin. 2005, 69, 1311–1319. [Google Scholar] [CrossRef] [PubMed]
  4. Li, D.; Zhou, B.; Lv, B. Antibacterial Therapeutic Agents Composed of Functional Biological Molecules. J. Chem. 2020, 2020, 6578579. [Google Scholar] [CrossRef]
  5. British Infection Association. The epidemiology, prevention, investigation and treatment of Lyme borreliosis in United Kingdom patients: A position statement by the British Infection Association. J. Infect. 2011, 62, 329–338. [Google Scholar] [CrossRef] [PubMed]
  6. Bansal, C. Cephalosporin in the management of children with acute otitis media. Int. J. Health Sci. 2021, 5, 14104. [Google Scholar] [CrossRef]
  7. Snodgrass, A.; Motaparthi, K. 9-Systemic Antibacterial Agents. Comp. Dermatol. Drug Ther. 2021, 69–98.e13. [Google Scholar]
  8. Mergenhagen, K.A.; Wattengel, B.A.; Skelly, M.K.; Clark, C.M.; Russo, T.A. Fact versus Fiction: A Review of the Evidence behind Alcohol and Antibiotic Interactions. Antimicrob. Agents Chemother. 2020, 64. [Google Scholar] [CrossRef]
  9. Rizzo, L.; Meric, S.; Kassinos, D.; Guida, M.; Russo, F.; Belgiorno, V. Degradation of diclofenac by TiO2 photocatalysis: UV absorbance kinetics and process evaluation through a set of toxicity bioassays. Water Res. 2009, 43, 979–988. [Google Scholar] [CrossRef]
  10. Andreozzi, R.; Caprio, V.; Marotta, R.; Vogna, D. Paracetamol oxidation from aqueous solutions by means of ozonation and H2O2/UV system. Water Res. 2003, 37, 993–1004. [Google Scholar] [CrossRef]
  11. Benzarti, Z.; Saadi, H.; Abdelmoula, N.; Hammami, I.; Pedro, M.; Graça, F.; Alrasheedi, N.; Louhichi, B.; Seixas de Melo, J. Enhanced dielectric and photocatalytic properties of Li-doped ZnO nanoparticles for sustainable methylene blue degradation with reduced lithium environmental impact. Ceram. Int. 2025, 51, 47170–47184. [Google Scholar] [CrossRef]
  12. Resmi, V.; Soney, J.; Dhannia, T. Photocatalytic activity of ZnO nanoparticle and ZnO-TiO2 nanocomposite synthesized using egg-white mediated co-precipitation technique with microwave irradiation. Opt. Mater. 2025, 168, 117440. [Google Scholar] [CrossRef]
  13. Kumari, P.; Misra, K.; Chattopadhyay, S.; Samanta, S. A brief review on transition metal ion doped ZnO nanoparticles and its optoelectronic applications. Mater. Proceed. 2021, 43, 3297–3302. [Google Scholar] [CrossRef]
  14. Hamrouni, A.; Moussa, M.; Fessi, N.; Palmisano, N.; Ceccato, R.; Rayes, A.; Parrino, F. Solar Photocatalytic Activity of Ba-Doped ZnO Nanoparticles: The Role of Surface Hydrophilicity. Nanomaterials 2023, 23, 2742. [Google Scholar] [CrossRef]
  15. Hakki, H.; Sillanpää, M. Comprehensive analysis of photocatalytic and photoreactor challenges in photocatalytic wastewater treatment: A case study with ZnO photocatalyst. Mater. Sci. Semicond. Process. 2024, 181, 108592. [Google Scholar] [CrossRef]
  16. Chang, P.; Wang, Y.; Wang, Y.; Zhu, Y. Current trends on In2O3 based heterojunction photocatalytic systems in photocatalytic application. Chem. Eng. J. 2022, 450, 137804. [Google Scholar] [CrossRef]
  17. Friedmann, D.; Caruso, R. Indium Oxides and Related Indium-based Photocatalysts for Water Treatment: Materials Studied, Photocatalytic Performance, and Special Highlights. Sol. RRL 2021, 5, 2100086. [Google Scholar] [CrossRef]
  18. Letifi, H.; Dridi, D.; Litaiem, Y.; Ammar, S.; Dimassi, W.; Chtourou, R. High Efficient and Cost Effective Titanium Doped Tin Dioxide Based Photocatalysts Synthesized via Co-precipitation Approach. Catalysts 2021, 11, 803. [Google Scholar] [CrossRef]
  19. Nipa, S.T.; Akter, R.; Raihan, A.; Rasul, S.; Som, U.; Ahmed, S.; Alam, J.; Khan, M.; Enzo, S.; Rahman, W. State-of-the-art biosynthesis of tin oxide nanoparticles by chemical precipitation method towards photocatalytic application. Environ. Sci. Pollut. Res. 2022, 29, 10871–10893. [Google Scholar] [CrossRef]
  20. Thuan, D.; Ngo, H.; Thi, H.; Chu, T. Photodegradation of hazardous organic pollutants using titanium oxides -based photocatalytic: A review. Environ. Res. 2023, 229, 116000. [Google Scholar] [CrossRef]
  21. Hoai, P.; Huong, N. Latest avenues on titanium oxide-based nanomaterials to mitigate the pollutants and antibacterial: Recent insights, challenges, and future perspectives. Chemosphere 2023, 324, 138372. [Google Scholar] [CrossRef] [PubMed]
  22. Arora, I.; Chawla, H.; Chandra, A.; Sagadevan, S.; Garg, S. Advances in the strategies for enhancing the photocatalytic activity of TiO2: Conversion from UV-light active to visible-light active photocatalyst. Inorg. Chem. Comm. 2022, 143, 109700. [Google Scholar] [CrossRef]
  23. Joshi, B.; Chaudhri, A. Sol–Gel-Derived Cu-Doped ZnO Thin Films for Optoelectronic Applications. ACS Omega 2022, 7, 21877–21881. [Google Scholar] [CrossRef] [PubMed]
  24. Li, Y.; Xu, L.; Li, X.; Shen, X.; Wang, A. Effect of aging time of ZnO sol on the structural and optical properties of ZnO thin films prepared by sol–gel method. Appl. Surf. Sci. 2010, 256, 4543–4547. [Google Scholar] [CrossRef]
  25. Xu, L.; Li, X.; Chen, Y.; Xu, F. Structural and optical properties of ZnO thin films prepared by sol–gel method with different thickness. Appl. Surf. Sci. 2011, 257, 4031–4037. [Google Scholar] [CrossRef]
  26. Badoni, A.; Sharma, R.; Prakash, J. Titanium Dioxide Based Functional Materials for Antibacterial and Antiviral Applications. ACS Publ. 2024, 8, 257–280. [Google Scholar]
  27. Swathi, S.; Babu, E.; Yuvakkumar, R.; Ravi, G.; Chinnathambi, A.; Alharbi, S.; Velauthapillai, D. Branched and unbranched ZnO nanorods grown via chemical vapor deposition for photoelectrochemical water-splitting applications. Ceram. Int. 2021, 47, 9785–9790. [Google Scholar] [CrossRef]
  28. Vega, N.; Straube, B.; Marin-Ramirez, O.; Comedi, D. Low temperature chemical vapor deposition as a sustainable method to obtain c-oriented and highly UV luminescent ZnO thin films. Mater. Lett. 2023, 333, 133684. [Google Scholar] [CrossRef]
  29. Alshoaibi, A. The Influence of Annealing Temperature on the Microstructure and Electrical Properties of Sputtered ZnO Thin Films. Inorganics 2024, 12, 236. [Google Scholar] [CrossRef]
  30. Zou, X.; Ke, J.; Hao, J.; Yan, X.; Tian, Y. A new method for synthesis of ZnO flower-like nanostructures and their photocatalytic performance. Phys. Cond. Matter. 2022, 624, 413395. [Google Scholar] [CrossRef]
  31. Abdallah, B.; Kakhia, M.; Obaide, A. Morphological and Structural Studies of ZnO Nanotube Films Using Thermal Evaporation Technique. Plasmonics 2021, 16, 1549–1556. [Google Scholar] [CrossRef]
  32. Zeid, S.; Leprince-Wang, Y. Advancements in ZnO-Based Photocatalysts for Water Treatment: A Comprehensive Review. Crystals 2024, 14, 611. [Google Scholar]
  33. Yavaş, A.; Güler, S.; Erol, M. Growth of ZnO nanoflowers: Effects of anodization time and substrate roughness on structural, morphological, and wetting properties. J. Australas. Ceram. Soc. 2020, 56, 995–1003. [Google Scholar] [CrossRef]
  34. Speaks, D.T. Effect of concentration, aging, and annealing on sol gel ZnO and Al-doped ZnO thin films. Int. J. Mech. Mater. Eng. 2020, 15, 2. [Google Scholar] [CrossRef]
  35. Mahroug, A.; Mahroug, I.; Berra, S.; Allali, D.; Hamrit, S.; Guelil, A.; Zoukel, A.; Ullah, S. Optical, luminescence, photocurrent and structural properties of sol-gel ZnO fibrous structure thin films for optoelectronic applications: A combined experimental and DFT study. Opt. Mater. 2023, 142, 114043. [Google Scholar] [CrossRef]
  36. Ebrahimifard, R.; Abdizadeh, H.; Golobostanfard, M.R. Controlling the extremely preferred orientation texturing of sol–gel derived ZnO thin films with sol and heat treatment parameters. J. Sol-Gel Sci. Technol. 2020, 93, 28–35. [Google Scholar] [CrossRef]
  37. Guglielmi, M.; Carturan, G. Precursors for sol-gel preparations. J. Non-Cryst. Solids 1988, 100, 16–30. [Google Scholar] [CrossRef]
  38. Liu, Z.; Jin, Z.; Li, W.; Qiu, J. Preparation of ZnO porous thin films by sol–gel method using PEG template. Mater. Lett. 2005, 59, 3620–3625. [Google Scholar] [CrossRef]
  39. Cullity, B.; Stock, S. Elements of X-Ray Diffraction, 2nd ed.; Prentice-Hall, Inc.: Saddle River, NJ, USA, 2001; p. 388. [Google Scholar]
  40. Abdullin, K.; Gabdullin, M.; Zhumagulov, S.; Ismailova, G.; Gritsenko, L.; Kedruk, Y.; Mirzaeian, M. Stabilization of the Surface of ZnO Films and Elimination of the Aging Effect. Materials 2021, 14, 6535. [Google Scholar] [CrossRef]
  41. Folawewo, A.; Bala, M. Nanocomposite Zinc Oxide-Based Photocatalysts: Recent Developments in Their Use for the Treatment of Dye-Polluted Wastewater. Water 2022, 14, 3899. [Google Scholar] [CrossRef]
  42. Fathollahi, V.; Amini, M. Sol–gel preparation of highly oriented gallium-doped zinc oxide thin films. Mater. Lett. 2001, 50, 235–239. [Google Scholar] [CrossRef]
  43. Tirado-Guerra, S.; Olvera, M.; Maldonado, A.; Castaneda, L. Chemically sprayed ZnO: F thin films deposited from diluted solutions: Effect of the time of aging on physical characteristics. Sol. Energy Mater. Sol. Cells 2006, 90, 2346–2355. [Google Scholar] [CrossRef]
  44. Rozati, S.; Moradi, S.; Golshahi, S.; Martins, R.; Fortunato, E. Electrical, structural and optical properties of fluorine-doped zinc oxide thin films: Effect of the solution aging time. Thin Solid. Films 2009, 518, 1279–1282. [Google Scholar] [CrossRef]
  45. Toubane, M.; Tala-Ighil, R.; Bensouici, F.; Bououdina, M.; Cai, W.; Liu, S.; Souier, M.; Iratni, A. Structural, optical and photocatalytic properties of ZnO nanorods: Effect of aging time and number of layers. Ceram. Int. 2016, 42, 9673–9685. [Google Scholar] [CrossRef]
  46. Muchuweni, E.; Sathiaraj, T.; Nyakotyo, H. Synthesis and characterization of zinc oxide thin films for optoelectronic applications. Heliyon 2017, 3, e00285. [Google Scholar] [CrossRef]
  47. Pankove, J. Optical processes in semiconducting thin films. Thin Solid. Films 1982, 80, 172. [Google Scholar] [CrossRef]
  48. Ghosh, R.; Basak, D.; Fujihara, S. Effect of substrate-induced strain on the structural, electrical, and optical properties of polycrystalline ZnO thin films. J. Appl. Phys. 2004, 96, 2689–2692. [Google Scholar] [CrossRef]
  49. Srikant, V.; Clarke, D. Optical absorption edge of ZnO thin films: The effect of substrate. J. Appl. Phys. 1997, 81, 6357–6364. [Google Scholar] [CrossRef]
  50. Rao, T.; Santhoshkumar, M. Effect of thickness on structural, optical and electrical properties of nanostructured ZnO thin films by spray pyrolysis. Appl. Surf. Sci. 2009, 255, 4579–4584. [Google Scholar] [CrossRef]
  51. Taunk, P.; Das, R.; Bisen, D.; Tamrakar, R. Structural characterization and photoluminescence properties of zinc oxide nano particles synthesized by chemical route method. J. Radiat. Res. Appl. Sci. 2015, 8, 433–438. [Google Scholar] [CrossRef]
  52. Abdallah, B.; Jazmati, A.; Refaai, R. Oxygen effect on structural and optical properties of ZnO thin films deposited by rf magnetron sputtering. Mater. Res. 2016, 20, 0478. [Google Scholar] [CrossRef]
  53. Abdallah, B.; Zetoun, W.; Tello, A. Deposition of ZnO thin films with different powers using RF magnetron sputtering method: Structural, electrical and optical study. Heliyon 2024, 10, e27606. [Google Scholar] [CrossRef]
  54. Akazawa, H. Photoluminescence studies of transparent conductive ZnO films to identify their donor species. AIP Adv. 2019, 9, 045202. [Google Scholar] [CrossRef]
  55. Aprile, C.; Corma, A.; García, H. Enhancement of the photocatalytic activity of TiO2 through spatial structuring and particle size control: From subnanometric to submillimetric length scale. Phys. Chem. Chem. Phys. 2008, 10, 769–783. [Google Scholar] [CrossRef]
  56. Ramasamy, B.; Jeyadharmarajan, J.; Chinnaiyan, P. Novel organic assisted Ag-ZnO photocatalyst for atenolol and acetaminophen photocatalytic degradation under visible radiation: Performance and reaction mechanism. Environ. Sci. Pollut. Res. 2021, 28, 39637–39647. [Google Scholar] [CrossRef]
  57. Wang, S.; Wu, J.; Lu, X.; Xu, W.; Gong, Q.; Ding, J.; Dan, B.; Xie, P. Removal of acetaminophen in the Fe2+/persulfate system: Kinetic model and degradation pathways. Chem. Eng. J. 2019, 358, 1091–1100. [Google Scholar] [CrossRef]
  58. Ali, A.; Alwared, A. Photocatalytic continuous degradation of pharmaceutical pollutants by zeolite/Fe3O4/CuS/CuWO4 nanocomposite under direct sunlight. Res. Eng. 2024, 24, 103234. [Google Scholar] [CrossRef]
  59. Hanafi, M.; Sapawe, N. Effect of initial concentration on the photocatalytic degradation of remazol brilliant blue dye using nickel catalyst. Mater. Today 2020, 31, 318–320. [Google Scholar] [CrossRef]
Crystals 16 00008 g001aCrystals 16 00008 g001b
Figure 1. SEM pictures of (a) ZnO/0 d, (b) ZnO/1 d, (c) ZnO/3 d, (d) ZnO/5 d, (e) ZnO/10 d, (f) ZnO/15 d, and (g) ZnO/30 d thin films.
Figure 1. SEM pictures of (a) ZnO/0 d, (b) ZnO/1 d, (c) ZnO/3 d, (d) ZnO/5 d, (e) ZnO/10 d, (f) ZnO/15 d, and (g) ZnO/30 d thin films.
Crystals 16 00008 g001aCrystals 16 00008 g001b
Crystals 16 00008 g002
Figure 2. XRD pattern of the prepared (a) ZnO/0 d, (b) ZnO/10 d, and (c) ZnO/30 d thin films.
Figure 2. XRD pattern of the prepared (a) ZnO/0 d, (b) ZnO/10 d, and (c) ZnO/30 d thin films.
Crystals 16 00008 g002
Crystals 16 00008 g003
Figure 3. Fourier transform infrared (FTIR) spectra of ZnO/30 d film in the region 350–950 cm−1 after annealing at 500 °C for 1 h.
Figure 3. Fourier transform infrared (FTIR) spectra of ZnO/30 d film in the region 350–950 cm−1 after annealing at 500 °C for 1 h.
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Crystals 16 00008 g004
Figure 4. (a) UV–visible patterns and (b) energy band gap calculated from Tauc’s equation for ZnO films obtained from sols with varying aging times.
Figure 4. (a) UV–visible patterns and (b) energy band gap calculated from Tauc’s equation for ZnO films obtained from sols with varying aging times.
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Crystals 16 00008 g005
Figure 5. Room temperature of PL spectra of ZnO/0 d, ZnO/10 d, and ZnO/30 d films.
Figure 5. Room temperature of PL spectra of ZnO/0 d, ZnO/10 d, and ZnO/30 d films.
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Crystals 16 00008 g006
Figure 6. (a) Photobleaching of Cefuroxime in distilled water by ZnO/0 d, ZnO/1 d, ZnO/3 d, ZnO/5 d, ZnO/10 d, ZnO/15 d and ZnO/30 d thin films, (b) pseudo-first-order kinetic plot, (c) decomposition of Cefuroxime under UV light illumination, and (d) absorbance spectra of the degradation of drug after 4 h photocatalysis.
Figure 6. (a) Photobleaching of Cefuroxime in distilled water by ZnO/0 d, ZnO/1 d, ZnO/3 d, ZnO/5 d, ZnO/10 d, ZnO/15 d and ZnO/30 d thin films, (b) pseudo-first-order kinetic plot, (c) decomposition of Cefuroxime under UV light illumination, and (d) absorbance spectra of the degradation of drug after 4 h photocatalysis.
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Crystals 16 00008 g007
Figure 7. (a) Photobleaching of Cefuroxime in tap water by ZnO/0 d, ZnO/1 d, ZnO/3 d, ZnO/5 d, ZnO/10 d, ZnO/15 d, and ZnO/30 d thin films, (b) pseudo-first-order kinetic plot under UV light illumination.
Figure 7. (a) Photobleaching of Cefuroxime in tap water by ZnO/0 d, ZnO/1 d, ZnO/3 d, ZnO/5 d, ZnO/10 d, ZnO/15 d, and ZnO/30 d thin films, (b) pseudo-first-order kinetic plot under UV light illumination.
Crystals 16 00008 g007
Crystals 16 00008 g008
Figure 8. Bleaching kinetics of Cefuroxime in distilled water by ZnO films with different initial concentrations: (a) 3, (b) 5, and (c) 10 ppm.
Figure 8. Bleaching kinetics of Cefuroxime in distilled water by ZnO films with different initial concentrations: (a) 3, (b) 5, and (c) 10 ppm.
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Crystals 16 00008 g009
Figure 9. Photostabillity of sol–gel ZnO films in (a) distilled and (b) tap water under ultraviolet light illumination.
Figure 9. Photostabillity of sol–gel ZnO films in (a) distilled and (b) tap water under ultraviolet light illumination.
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Table 1. Crystallite size and the parameters of the crystalline lattice of ZnO films obtained from sol aged for 0, 10, and 30 days.
Table 1. Crystallite size and the parameters of the crystalline lattice of ZnO films obtained from sol aged for 0, 10, and 30 days.
FilmsCrystallite
a.u.		Microstraine,
size		Characteristics of the Crystalline Lattice, ÅR Values
ZnO/0 d23 nm0.7 × 10−3a, b = 3.2389 Å
c = 5.1924 Å		Rp = 5.46 Rwp = 7.17 Rexp = 0.03
ZnO/10 d19 nm0.6 × 10−3a, b = 3.2424 Å
c = 5.1972 Å		Rp = 5.53 Rwp = 7.32 Rexp = 0.03
ZnO/30 d16 nm0.5 × 10−3a, b = 3.2442 Å
c = 5.1993 Å		Rp = 5.57 Rwp = 7.39 Rexp = 0.14
Table 2. Cefuroxime degradation rates and percentages in distilled and tap water using sol–gel ZnO sheets.
Table 2. Cefuroxime degradation rates and percentages in distilled and tap water using sol–gel ZnO sheets.
FilmsDistilled Water
k, h−1 D, %		Tap Water
k, h−1 D, %
ZnO/0 d0.199554.120.24861.29
ZnO/1 d0.283165.590.334171.68
ZnO/3 d0.337471.860.337475.45
ZnO/5 d0.398677.420.428381.00
ZnO/10 d0.457181.540.498785.30
ZnO/15 d0.501884.230.614791.40
ZnO/30 d0.601890.140.785396.24
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Kaneva, N. Photocatalytic Properties of Sol–Gel Films Influenced by Aging Time for Cefuroxime Decomposition. Crystals 2026, 16, 8. https://doi.org/10.3390/cryst16010008

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Kaneva N. Photocatalytic Properties of Sol–Gel Films Influenced by Aging Time for Cefuroxime Decomposition. Crystals. 2026; 16(1):8. https://doi.org/10.3390/cryst16010008

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Kaneva, Nina. 2026. "Photocatalytic Properties of Sol–Gel Films Influenced by Aging Time for Cefuroxime Decomposition" Crystals 16, no. 1: 8. https://doi.org/10.3390/cryst16010008

APA Style

Kaneva, N. (2026). Photocatalytic Properties of Sol–Gel Films Influenced by Aging Time for Cefuroxime Decomposition. Crystals, 16(1), 8. https://doi.org/10.3390/cryst16010008

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