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Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods

Institute of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania
Author to whom correspondence should be addressed.
Crystals 2021, 11(8), 943;
Received: 4 August 2021 / Accepted: 12 August 2021 / Published: 13 August 2021
Functional inorganic materials are an indispensable part of innovative technologies, which are essential to the development of many fields of industry. The use of new materials, nanostructures, or multicomponent composites with specific chemical or physical properties promotes technological progress in electronics, optoelectronics, catalysis, biomedicine, and many other areas that are concerned with plenty of aspects of human life. Due to the broad and diverse range of the potential applications of functional inorganic materials, the development of superior synthesis pathways, reliable characterization, and a deep understanding of the structure–property relationships in materials, are rightfully considered to be fundamentally important scientific issues. Only synergetic efforts of scientists dealing with the synthesis, functionalization, and characterization of materials will lead to the development of future technologies. The Special Issue on “Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods” covers a broad range of preparation routes, characterization, and the application of functional inorganic materials, as well as hybrid materials that are important in the fields of electronics, optics, biomedicine, and others.
The sol-gel method is a simple, time- and cost-effective synthetic approach providing high homogeneity and stoichiometry control of the products. These reasons make it highly suitable for the preparation of mixed-metal oxide materials and different solid solutions. For instance, Grazenaite et al. [1] employed an aqueous sol-gel method for the preparation of Ga-substituted cobalt–chromium spinels as ceramic pigments. The ion substitution resulted in significant color tuning. This demonstrated that the full substitution of Cr3+ by Ga3+ ions led to the formation of light blue powders, which yielded a violet blue color for the corresponding ceramic glaze. Karoblis et al. [2] utilized the sol-gel method for the synthesis of (1−x)SrTiO3-xBiMnO3 solid solutions in order to obtain new multiferroic material. The results indicated that single-phase perovskites with a cubic structure can only be synthesized up to x = 0.3. A higher BiMnO3 content led to the formation of a negligible amount of the neighboring Mn3O4 phase. Nevertheless, some compositional trends were observed in this range. The grain size increased drastically with an increase of BiMnO3, moreover, the gradual increase of the BiMnO3 content resulted in noticeably higher magnetization values. Finally, using the sol-gel method, Inkrataite et al. [3] prepared cerium and chromium co-doped gadolinium–aluminum–gallium garnet (GAGG, Gd3Al2Ga3O12). The remarkable feature of this study is that an exceptionally intense emission in the near-infrared region (NIR) was achieved with an extremely low doping level. The chromium content in the obtained materials reached only 15 ppm. Another example of optical materials was provided by Buyer et al. [4]. The authors were able to synthesize Eu3+-substituted NaY[SO4]2 H2O under hydrothermal conditions. The anhydrated version of this material (NaY[SO4]2) was obtained by the post-annealing of as-prepared species. The structural and thermal properties of the synthesized compound were investigated in detail. Both compounds exhibited a strong emission in red region.
Wet chemical methods allow not only crystalline to synthesize, but also amorphous materials, which can be very attractive for medical applications. A hydrothermal approach was employed by Anh Tuan et al. [5] for the preparation of bioactive glass 58SiO2-33CaO-9P2O5. The proposed synthetic approach avoided the use of harmful acid catalysts and was confirmed as one of the ideal methods for the preparation of ternary bioactive glass. For specific medical applications more complex hybrid organic–inorganic structures can be used. For example, the successful preparation of the biocompatible nanohybrid of ciprofloxacin-Ag/TiO2/chitosan was demonstrated by Zafar et al. [6]. The obtained nanaheterostructures were shown to be effective against mastitis causing E. coli.
Titanium dioxide, besides being used in heterostructures for biomedical applications, is a very technologically important material, which can be utilized for a broad range of applications. In this light, simple and cost-effective methods for the synthesis of TiO2 are highly desirable. Serga et al. [7] demonstrated for the first time the possibilities of the extraction–pyrolytic method (EPM) for the production of nanocrystalline TiO2 powders. It was observed that the EPM permitted the production of both monophase (anatase or rutile polymorph) and biphase (mixed anatase–rutile polymorphs) nanocrystalline TiO2. The influence of poly(titanium oxide) obtained using the sol-gel method on the viscoelastic and thermophysical properties of interpenetrating polymer networks (IPNs) based on cross-linked polyurethane (PU) and poly(hydroxyethyl methacrylate) (PHEMA), was studied by Tsebriienko and Popov [8]. It was found that an increase in poly(titanium oxide) content led to a decrease in the intensity of the relaxation maximum for PHEMA phase and an increase in the effective crosslinking density due to the partial grafting of the inorganic component to acrylate.
Carbon-supported MnO2 nanocomposites for the application of supercapacitors were fabricated by Jablonskiene et al. [9] using the microwave-assisted heating method. For comparison, the nanocomposites were synthesized by one-step and two-step approaches. The high specific capacitance of 980.7 F g−1 was achieved from cyclic voltammetry measurements, whereas the specific capacitance of 949.3 F g−1 at 1 A g−1 was obtained from a galvanostatic charge/discharge test. The specific capacitance retention was 93% after 100 cycles at 20 A g−1, indicating good electrochemical stability.
Zeng et al. [10] utilized hydrothermally synthesized ZnO nanowires for the fabrication of 2D Bi2Se3/ZnO heterojunction, which was employed for the broadband photodetection. The fabricated heterojunction device demonstrated not only an enhanced photoresponsivity of 0.15 A/W at 377 nm, which was three times higher than that of bare ZnO nanowire (0.046 A/W), but also achieved a broadband photoresponse from UV to near-infrared region was achieved.
The present Special Issue on “Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods” demonstrates the versatility of wet chemical methods for the preparation of functional materials for a broad range of applications. It can be considered as a status report reviewing the progress that has been achieved in the processing of inorganic materials.

Author Contributions

Conceptualization, A.Z., A.K. and L.T.-T.; writing—original draft preparation, A.Z., A.K. and L.T.-T.; writing—review and editing, A.Z., A.K. and L.T.-T.; funding acquisition, A.Z. and A.K. All authors have read and agreed to the published version of the manuscript.


This project has received funding from European Social Fund (project No. 09.3.3-LMT-K-712-19-0069) under grant agreement with the Research Council of Lithuania (LMTLT).

Conflicts of Interest

The authors declare no conflict of interest.


  1. Grazenaite, E.; Garskaite, E.; Stankeviciute, Z.; Raudonyte-Svirbutaviciene, E.; Zarkov, A.; Kareiva, A. Ga-substituted cobalt-chromium spinels as ceramic pigments produced by sol-gel synthesis. Crystals 2020, 10, 1078. [Google Scholar] [CrossRef]
  2. Karoblis, D.; Diliautas, R.; Raudonyte-Svirbutaviciene, E.; Mazeika, K.; Baltrunas, D.; Beganskiene, A.; Zarkov, A.; Kareiva, A. The Synthesis and characterization of sol-gel-derived SrTiO3-BiMnO3 solid solutions. Crystals 2020, 10, 1125. [Google Scholar] [CrossRef]
  3. Inkrataite, G.; Laurinavicius, G.; Enseling, D.; Zarkov, A.; Jüstel, T.; Skaudzius, R. Characterization of GAGG doped with extremely low levels of chromium and exhibiting exceptional intensity of emission in NIR region. Crystals 2021, 11, 673. [Google Scholar] [CrossRef]
  4. Buyer, C.; Enseling, D.; Jüstel, T.; Schleid, T. Hydrothermal synthesis, crystal structure, and spectroscopic properties of pure and Eu3+-doped NaY [SO4]2 H2O and Its Anhydrate NaY [SO4]2. Crystals 2021, 11, 575. [Google Scholar] [CrossRef]
  5. Anh Tuan, T.; Guseva, E.V.; Anh Tien, N.; Tan Dat, H.; Vuong, B.X. Simple and acid-free hydrothermal synthesis of bioactive glass 58SiO2-33CaO-9P2O5 (wt%). Crystals 2021, 11, 283. [Google Scholar] [CrossRef]
  6. Zafar, N.; Uzair, B.; Niazi, M.B.K.; Samin, G.; Bano, A.; Jamil, N.; Un-Nisa, W.; Sajjad, S.; Menaa, F. Synthesis and characterization of potent and safe ciprofloxacin-loaded Ag/TiO2/CS nanohybrid against mastitis causing E. coli. Crystals 2021, 11, 319. [Google Scholar] [CrossRef]
  7. Serga, V.; Burve, R.; Krumina, A.; Romanova, M.; Kotomin, E.A.; Popov, A.I. Extraction–pyrolytic method for TiO2 polymorphs production. Crystals 2021, 11, 431. [Google Scholar] [CrossRef]
  8. Tsebriienko, T.; Popov, A.I. Effect of poly(titanium oxide) on the viscoelastic and thermophysical properties of interpenetrating polymer networks. Crystals 2021, 11, 794. [Google Scholar] [CrossRef]
  9. Jablonskiene, J.; Simkunaite, D.; Vaiciuniene, J.; Stalnionis, G.; Drabavicius, A.; Jasulaitiene, V.; Pakstas, V.; Tamasauskaite-Tamasiunaite, L.; Norkus, E. Synthesis of carbon-supported mno2 nanocomposites for supercapacitors application. Crystals 2021, 11, 784. [Google Scholar] [CrossRef]
  10. Zeng, Z.; Wang, D.; Wang, J.; Jiao, S.; Liu, D.; Zhang, B.; Zhao, C.; Liu, Y.; Liu, Y.; Xu, Z.; et al. Broadband detection based on 2D Bi2Se3/ZnO nanowire heterojunction. Crystals 2021, 11, 169. [Google Scholar] [CrossRef]
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Zarkov, A.; Kareiva, A.; Tamasauskaite-Tamasiunaite, L. Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods. Crystals 2021, 11, 943.

AMA Style

Zarkov A, Kareiva A, Tamasauskaite-Tamasiunaite L. Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods. Crystals. 2021; 11(8):943.

Chicago/Turabian Style

Zarkov, Aleksej, Aivaras Kareiva, and Loreta Tamasauskaite-Tamasiunaite. 2021. "Advances in Functional Inorganic Materials Prepared by Wet Chemical Methods" Crystals 11, no. 8: 943.

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