2D nanocrystals of metal oxides and hydroxides with nanosheet/nanoflake morphology in biomedicine, energy and chemistry

Wang W., Shen J., Meng Y., Ye M., Lin S., Zhao Q., Wang L., Cheung K.M., Wu S., Zheng Y., Liu X., Chu P.K., Yeung K.W., Zhang Z.

[This corrects the article DOI: 10.1016/j.bioactmat.2021.08.027.].

Qi Y., Sadi M.A., Hu D., Zheng M., Wu Z., Jiang Y., Chen Y.P.

Strain engineering is a promising way to tune the electrical, electrochemical, magnetic, and optical properties of two-dimensional (2D) materials, with the potential to achieve high-performance 2D-material-based devices ultimately. This review discusses the experimental and theoretical results from recent advances in the strain engineering of 2D materials. We summarize some novel methods to induce strain and then highlight the tunable electrical, and optical/optoelectronic properties of 2D materials via strain engineering including particularly the previously less discussed strain tuning of superconducting, magnetic, and electrochemical properties. Also, the future perspectives of strain engineering are given for its potential applications in functional devices. The state of the survey presents the ever-increasing advantages and popularity of strain engineering for tuning properties of 2D materials. It provides suggestions and insights for further research and applications in optical, electronic, and spintronic devices. This article is protected by copyright. All rights reserved

Gulina L.B., Skripnyak P.O., Tolstoy V.P.

The surfactant-free synthesis of a solid film of ceria was carried out at the air–water interface from an aqueous solution of Ce(NO3)3 and gaseous NH3 as reactants. The synthesized CeO2−x • n H2O film consists of 2D nanocrystals with a fluorite structure. The film can form a planar coating on the surface of a solid substrate or transform into curved fragments upon drying, depending on the synthesis conditions.

Zhang S., Song P., Zheng Y., Ding Y., Wang Q.

Ethanol, as one of the common volatile organic compounds (VOCs), has serious harm to the human central nervous system. The high-efficiency detection of ethanol gas at room temperature (RT) has attracted widespread attention in the field of current gas-sensing detection. Here, we designed and prepared ternary nanocomposites constructed with two-dimensional MXene and MoO 2 /MoO 3 nanosheets, which can be used in the field of low-concentration ethanol detection at RT. The MoO 2 /MoO 3 /MXene nanocomposites make full use of the excellent electrical conductivity and large specific surface area of MXene, which provides more active adsorption sites and reaction centers. Moreover, the construction of n-n heterojunctions between uniformly grown MoO 2 and MoO 3 nanosheets significantly enhances the response of the sensor. The gas sensing results revealed that MoO 2 /MoO 3 /MXene nanocomposites showed high response (Ra/Rg = 19.77@200 ppm) to ethanol at RT, with a detection limit of 5 ppm (Ra/Rg = 2.07). At the same time, the sensor also has excellent selectivity and fast response-recovery to ethanol (46 s/276 s). Further, the possible gas sensing mechanism of the composites was proposed and discussed. This work suggests the promising applications of metal oxides heterojunctions/2D hybrid materials for VOCs gas sensing detection at RT. • MoO 2 /MoO 3 /MXene ternary nanocomposites were rapidly synthesized via a one-step hydrothermal method. • The synergistic effects allow MoO 2 /MoO 3 /MXene ternary nanocomposites exhibit high ethanol-sensing performance at room temperature. • The construction of metal oxide heterojunction/2D hybrid materials for VOCs gas detection at room temperature.

Li J., Zhang W., Zheng W.

The highly booming of grid-scale and intermittent energy system pressurizes fast reaction dynamics in energy storage and conversion systems. Construction of aqueous rechargeable multivalent metal-ion batteries is a promising solution as the ionic diffusivity in aqueous electrolyte is generally elevated with 1–2 orders of magnitude as compared with the organic electrolyte. Supplementarily, the aqueous electrolyte is commonly safe free of explosion and inexpensiveness. Layer-structured compounds are regarded as one of the ascendent active materials for aqueous multivalent metal-ion batteries owing to their steerable interlayer spacing. However, their practical implementation is hindered by the existing inevitable challenges, such as active materials dissolution, structural collapse, low electrical conductivity, etc. This review highlights on the application of layer-structured materials in aqueous rechargeable multivalent metal-ions batteries, furthermore, primarily focusing on clarification of the reaction mechanism and improved strategies are also discussed in detail, which thereof offers an insightful guideline for the future development of layer-structured compounds in electrochemical energy storage.

Liu W., Wei D., Zhao X., Xiao F., Yang C.

• Hierarchical hetero-structures of interconnected In-doped NiO nanosheets and layered montmorillonite were constructed. • In doping and MMT hybridization could regulate the initial resistance of the NiO sensor. • The coupling synergistic effect of In doping and MMT hybridization could greatly enhance the sensing performance. Here, hierarchical hetero-structures of montmorillonite (MMT) supported In-doped NiO (In−NiO/MMT) were constructed and evaluated as gas sensors for the response to gaseous volatile organic compounds in air. The cross-linking growth of In-doped NiO nanosheets on the MMT platelet was achieved by a facile deposition–precipitation and subsequent calcination process. By the MMT hybridization and In doping, the surface area, surface defects, and electric conductivity of NiO was somewhat increased, whereas its crystallite size decreased. Gas sensing tests showed that the selective response of NiO/MMT to xylene was significantly enhanced by the In doping. Specifically, the response to 100 ppm xylene for the optimal sensor based on In(5%)−NiO/MMT was 36.2 at 370 ℃, which was 21.8 times of that for NiO alone. In addition, the In(5%)−NiO/MMT based sensor demonstrated excellent repeatability and stability. The enhanced gas response by the MMT hybridization and In doping may be attributed to the decrease in hole concentration of NiO in air as well as the increase in surface defects. These results show a potential for aluminosilicate clays to developing highly sensitive and low-cost gas sensors through the construction of hierarchical hetero-structures with metal oxides.

Loy S., Xiang J., Yang W., Di Y., Zhao R., Wu F., Ma D., Li M., Li J.

Promising hydrothermal synthesis and calcination strategy is used in manufacturing the 3D hierarchical MnCo 2 O 4 @NiO nanosheets. This paper is a preliminary attempt to prepare a novel MnCo 2 O 4 @NiO electrode through an effectual hydrothermal procedure, in which the nickel foam is used as a backbone structure. At a current density of 1 A g −1 , the positive electrode material reveals a maximum specific capacitance of 1914 F g −1 . The specific capacitance of MnCo 2 O 4 @NiO remains 95.4% irrespective of 8000 cycles. The as-assembled supercapacitor (SC) exhibits an energy density of 40.04 Wh kg −1 at a power density of 770 W kg −1 . The result of this research highlights the evidence of the 3D hierarchical MnCo 2 O 4 @NiO structure for being an encouraging candidate for the forthcoming energy storage utilization. • The MnCo 2 O 4 @NiO composite electrode is synthesized via hydrothermal-calcination method. • The MnCo 2 O 4 @NiO composite electrode provides high specific capacitance of 1914 F g −1 . • The electrode exhibits exceptional cycling stability of 95.4% even after 10,000 cycles. • The MnCo 2 O 4 @NiO//AC ASCs device possesses high energy density and power density.

Zakaria S.A., Ahmadi S.H., Amini M.H.

A wide range of materials and nanomaterials have been considered gas sensors due to the growing needs of developed and developing societies. It has been more than six decades since Taguchi introduced the first commercial gas sensor, yet the development of sensors has grown exponentially and has not slowed down. Researchers always look for new materials with more efficient morphologies. It can probably be said that one of the newest materials discussed is LDH nanosheets, which has been discussed for less than two decades. Thus, in this review, after defining the general structure of LDH and giving a general description of nanomaterials, we have discussed the relevant terms and various methods of synthesis. The film preparation of nanomaterial sensor is then discussed in detail as a scalable approach in line with the various methods of nanomaterial synthesis (especially with a focus on LDH nanosheets). The following is discussed the unique properties of LDH nanosheets and their effect on the detection of various contaminants. Since LDH nanomaterials fall into both n- and p-type categories, the pollutant (gas) measurement approach has been investigated in both categories. This creates a specific comparative approach for the reader. Concisely, this study describes the use of LDH nanosheets in the field of gas sensors and may provide the idea for more extensive and practical research on LDHs.

Ren Y., Yan Y., Qi H.

Photothermal therapy (PTT) is a promising alternative therapy for benign or even malignant tumors. To improve the selective heating of tumor cells, target-specific photothermal conversion agents are often included, especially nanoparticles. Meanwhile, some indirect methods by manipulating the radiation and heat delivery are also adopted. Therefore, to gain a clear understanding of the mechanism, and to improve the controllability of PTT, a few issues need to be clarified, including bioheat and radiation transfer, localized and collective heating of nanoparticles, etc. In this review, we provide an introduction to the typical bioheat transfer and radiation transfer models along with the dynamic thermophysical properties of biological tissue. On this basis, we reviewed the most recent advances in the temperature control methods in PTT from macroscale to nanoscale. Most importantly, a comprehensive introduction of the localized and collective heating effects of nanoparticle clusters is provided to give a clear insight into the mechanism for PPT from the microscale and nanoscale point of view. • Recent advances in the light and heat transfer during PTT were summarized. • Localized and collective heating effects induced by nanoclusters were analyzed. • Insights into the mechanism for PTT from microscale and nanoscale were provided. • Temperature manipulation methods in micro and nanoscale should be further studied. • Thermal damage mechanism due to nanoparticle-cell interaction needs further investigation.

Zhang Y., Elsayed-Ali H.E.

The melting of Bi nanoparticles embedded in nanometer-thick amorphous Al film was studied by electron diffraction. The Bi nanoparticles were prepared by sputtering an Al-Bi-Al multilayer followed by annealing at 60 K above the Bi bulk melting point, Tm. For heating at a rate of ~ 3 K/min, the onset melting of the Bi nanoparticles was ~ 120 K below the Tm of Bi, as observed by the change of the unit cell volume with temperature. Lattice contraction with an anisotropic thermal expansion coefficient was observed. The large depression of the melting point is mainly attributed to the incoherent Al-Bi interfaces with defects at the interface of the Bi nanoparticles and surrounding Al.

Jia G., Hupfer M., Schulz M., Schmidl G., Dellith A., Diegel M., Müller R., Dellith J., Lindner F., Dietzek‐Ivanšić B., Plentz J.

Wang M., Feng Y., Zhang Y., Li S., Wu M., Xue L., Zhao J., Zhang W., Ge M., Lai Y., Mi J.

Three-dimensional hollow Ni-Co LDH with staggered nanosheets as the shell is synthesized from ZIF-67 template via the microwave treatment. The Ni-Co LDH electrode exhibits an ultrahigh high specific capacitance (2369.0F/g at 0.5 A/g) and the Ni-Co LDH//AC device delivers excellent cycling stability with 83.6% capacitance retention after 10,000 cycles. This work provides a promising way for fabricating unique and complex 3D hollow structure with satisfactory electrochemical performance from MOF templates. • Three-dimensional hollow Ni-Co LDH nanocages are successfully synthesized from ZIF-67 template via microwave heating treatment. • Its unique architecture can promote the free diffusion and lessen the transfer distance for electrons and ions during the process of electrochemical reactions. • The synergistic effects of Ni and Co ions can provide multiple redox reactions during the electrochemical charge/discharge process. • The Ni-Co LDH electrode exhibits a superior capacitance of 2369.0F/g at 0.5 A/g and excellent rate capability. • The Ni-Co LDH//AC asymmetric supercapacitor delivers excellent cycling stability with 83.6% capacitance retention after 10,000 cycles. Ni-Co layered double hydroxides (LDHs) have been extensively applied as promising supercapacitor materials due to their ultra-high theoretical capacitance and excellent redox activity. Herein, three-dimensional hollow Ni-Co LDH with staggered nanosheets as the shell was synthesized from ZIF-67 template via the microwave treatment. The Ni-Co LDH revealed a high specific capacitance (2369.0F/g at 0.5 A/g) and a satisfactory rate capability when used as the electrode materials, which could be attributed to its high specific surface area, more exposed active sites, and the synergistic effects between nickel and cobalt ions for promoting mass transfer. Moreover, the asymmetric supercapacitor device possessed the energy density and power density as high as 21.28 Wh/kg and 3741.0 W/kg, respectively. Meanwhile, the Ni-Co LDH//AC device delivered excellent cycling stability with 83.6% capacitance retention after 10,000 cycles. This strategy is promising to be applied in other devices for energy storage, such as Li/Na/K-ion batteries, fuel cells, solar cells, etc.

Lobinsky A.A., Popkov V.I.

• We proposed novel direct synthesis route of ultrathin amorphous CoCr-LDH nanosheets. • For synthesis was used facile and low-cost SILD technique. • Electrodes based on CoCr-LDH showed high specific capacity and cycling stability. • The synthesized material exhibit good electrocatalytic performance of HER in alkaline media. In this work, we present a novel facile route to direct the synthesis of amorphous CoCr-LDH nanosheets via the Successive Ionic Layer Deposition (SILD) method. The results showed that the as-synthesized product is formed as ultrathin amorphous CoCr-LDH nanosheets with a thickness of 6–8 nm. Electrochemical characterization of the electrode based on the CoCr-LDH nanolayers deposited on nickel foam shows a pseudocapacitive behavior with the high specific capacity (1080F/g at a current density of 1 A/g) and also low hydrogen evolution reaction (HER) overpotential (-175 mV at 10 mA/cm 2 ) in alkaline media. We believe that these nanomaterials are can be promising candidates for application in high-effeciency pseudocapacitors and electrocatalysts for water splitting in alkaline media.

Xu H., Wang C., He G., Chen H., Du Y.

Rational design and construction of well-defined hollow heterostructured nanomaterials assembled by ultrathin nanosheets overtakes crucial role in developing high-efficiency oxygen evolution reaction (OER) electrocatalysts. Herein, a reliable metal-organic framework-mediated and cation-exchange strategy to tune the geometric structure and multicomponent heterostructures has been proposed for the fabrication of hollow CoWO4-Co(OH)2 hierarchical nanoboxes assembled by rich ultrathin nanosheets. Benefiting from the hierarchical hollow nanostructure, the CoWO4-Co(OH)2 nanoboxes offer plenty of metal active centers available for reaction intermediates. Moreover, the well-defined nanointerfaces between CoWO4 and Co(OH)2 can function as the bridge for boosting the efficient electron transfer from CoWO4 to Co(OH)2. As a consequence, the optimized CoWO4-Co(OH)2 nanoboxes can exhibit outstanding electrocatalytic performance toward OER by delivering 10 mA cm-2 with a low overpotential of 280 mV and a small Tafel slope of 70.6 mV dec-1 as well as outstanding electrochemical stability. More importantly, this CoWO4-Co(OH)2 heterostructured nanocatalyst can couple with Pt/C to drive overall water splitting to achieve 10 mA cm-2 with a voltage of 1.57 V.

Suzuki R., Yamauchi Y., Sugahara Y.

During the past decade, various inorganic material-based Janus nanosheets have been prepared and their applications have been proposed. Inorganic material-based Janus nanosheets have various advantages over polymer-based Janus nanosheets, including the maintenance of their characteristic two-dimensional shape, and are expected to be applied as unique functional materials. Methods for regioselective functionalization of the two sides of the individual nanosheets are extremely important for the development of inorganic material-based Janus nanosheets. In this review, the preparation methods and applications of inorganic material-based Janus nanosheets are summarized from the point of view of inorganic nanosheet functionalization.

Gulina L.B., Shilovskikh E.E., Kasatkin I.A., Danilov D.V., Meleshko A.A., Tolstoy V.P.

Gulina L.B., Shilovskikh E.E., Tolstoy V.P.

Tolstoy V.P., Gulina L.B., Shilovskikh E.E.

The paper shows for the first time that 2D ZnO nanocrystals with the structure of wurtzite and Mn3O4 hausmanite and morphology of perforated nanoflakes can be obtained on the basis of compounds that are formed as a result of reactions occurring on the surface of aqueous solutions of acetates of the corresponding metals when it is treated in air atmosphere with gaseous NH3. Application of the marked nanocrystals on the silicon surface makes it hydrophobic in the case of ZnO and superhydrophilic in the case of Mn3O4. Using the proposed synthesis technique, sequential and multiple deposition of these compounds on the substrate surface can be performed and such “multilayers” can exhibit new properties.

Malygin A.A., Malkov A.A., Sosnov E.A.

The current state of research conducted within the framework of the leading scientific school of V.B. Aleskovskii “Chemistry of Highly Organized Substances” is presented, including both new fundamental and applied results on the synthesis of innovative solid-phase materials by molecular layering and the most promising areas of their implementation in industry, as well as achievements in the development of hardware and technological design of the molecular layering process.

Malygin A.A., Malkov A.A., Sosnov E.A.

The current state of research carried out by Valentin Borisovich Aleskovskii’s leading scientific school “Chemistry of Highly Organized Substances” is studied, including both new fundamental and applied results on the molecular layering synthesis of innovative solid-phase materials, and the most promising areas of their implementation in industry, as well as achievements in the equipment design for the molecular layering process.

Tolstoi V.P., Gulina L.B., Shilovskikh E.E.

We are the first to show that 2D ZnO nanocrystals with the wurtzite structure and Mn3O4 nanocrystals with the hausmannite structure having perforated nanosheet (PNS) morphology can be prepared on the basis of compounds that are formed in reactions occurring on the surface of aqueous solutions of corresponding metal acetates exposed to gaseous NH3. Application of these nanocrystals on silicon makes the silicon surface hydrophobic in the case of ZnO and superhydrophilic in the case of Mn3O4. The proposed synthetic method can provide sequential and multiple deposition of these compounds on a substrate. Such “multilayers” can exhibit new properties.

Alekseev Roman F., Saraev Andrey A., Kurenkova Anna Yu., Kozlova Ekaterina A.

The interest of the global scientific community in the problems of CO2 utilization and returning to the carbon cycle has markedly increased in recent years. Among various CO2 transformation processes, photocatalytic reduction is one of the most promising. Currently, much attention is paid to photocatalysts based on graphitic carbon nitride, since the use of g-C3N4 makes it possible to perform CO2 reduction under visible or solar light irradiation. To increase the reduction efficiency, g-C3N4 is subjected to various modifications with the most popular and promising approach being the synthesis of composite photocatalysts based on g-C3N4 with other semiconductors to form heterostructures. Depending on the type of semiconductor, transfer of photogenerated charge carriers in these systems can occur by various mechanisms, which largely determine the course of the process and the rates of formation of reaction products. This review addresses studies on the synthesis of composite photocatalysts based on g-C3N4, with emphasis being placed on the mechanisms of charge carrier transfer and the distribution of products of CO2 reduction.The bibliography includes 235 references.

Rempel Andrey A., Ovchinnikov Oleg V., Weinstein Ilya A., Rempel Svetlana V., Kuznetsova Yulia V., Naumov Andrei V., Smirnov Mikhail S., Eremchev Ivan Yu., Vokhmintsev Alexander S., Savchenko Sergey S.

Quantum dots are the most exciting representatives of nanomaterials. They are synthesized using advanced methods of nanotechnology pertaining to both inorganic and organic chemistry. Quantum dots possess unique physical and chemical properties; therefore, they are used in very different fields of physics, chemistry, biology, engineering and medicine. It is not surprising that the Nobel Prize in chemistry in 2023 was given for discovery and synthesis of quantum dots. This review addresses modern methods for the synthesis of quantum dots and their optical properties and practical applications. In the beginning, a short insight into the history of quantum dots is given. Many gifted scientists, including chemists and physicists, were engaged in these studies. The synthesis of quantum dots in solid and liquid matrices is described in detail. Quantum dots are well-known owing to their unique optical properties; that is why the attention in the review is focused on the quantum-size effect. The causes for fascinating blinking of quantum dots and techniques for observation of a single quantum dot are considered. The last part of the review describes mportant applications of quantum dots in biology, medicine and quantum technologies.The bibliography includes 772 references.

Meleshko A.A., Afinogenova A.G., Afinogenov G.E., Galushka V.V., Gulina L.B., Tolstoy V.P.

Ag(0)–ZnFeOH 0D–2D nanocomposite can be prepared by successive ionic layer deposition (SILD) on the titanium surface. The nanocomposite consists of 10–20 nm silver nanoparticles located on the surface of ZnFeOH 2D nanocrystals of the ultrathin nanosheet morphology. The morphology, composition, and crystal structure of the compound synthesized were studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. As shown by the method of diffusion into agar, the nanocomposite, compared to the initial nanocomponents, exhibits increased antibacterial activity and prolonged action toward Staphylococcus aureus and Escherichia coli bacterial strains.