MXene-based hybrid materials for electrochemical and photoelectrochemical H_(2) generation

The conversion of solar energy to produce clean hydrogen fuel through water splitting is an emerging strategy for efficiently storing solar energy in the form of solar fuel.This aligns with the increasing global demand for the development of an ideal energy alternative to fossil fuels that does not emit greenhouse gases.Electrochemical(EC) and photoelectrochemical(PEC) water splitting technologies have garnered significant attention worldwide for advanced hydrogen solar fuel production in recent decades.To achieve sustainable green H_(2) production,it is essential to create efficient catalyst materials that are low-cost and can replace expensive noble metal-based catalysts.These characteristics make them an ideal catalyst material for the process.Two-dimensional MXenes with M_(n+1)X_(n) structure have been identified as a promising option for EC and PEC water splitting due to their superior hydrophilicity,metal-like conductivity,large surface area,and adjustable surface chemistry.Here,we present a summary of recent advancements in the synthesis and performance enhancement methods for MXene hybrid materials in hydrogen production through EC and PEC water splitting.Furthermore,we examine the challenges and insights associated with the rational design of MXene-based hybrid materials to facilitate efficient water splitting for sustainable solar fuel production.

Syntheses and Structures of Three Hybrid Materials Using Vanadium Polyoxoanions and Macrocyclic Copper Complex as Building Blocks

The reactions of the four-coordinated macrocyclic copper complex [CuL]（ClO4）2（L = 1,4,8,11-tetraazacyclotetradecane） with NH4VO3 under different conditions gave three inorganic-organic hybrid materials of [CuL][VO3]2·2.33H2O（1）, [CuL]3[V（10）O（28）]·8H2O（2） and [Cu L]3[V6O（18）]·8H2O（3）. Single-crystal X-ray diffraction analyses reveal that three diverse vanadium polyoxoanions, [V6O（18）]6- ring, [V（10）O（28）]6- cluster, and [V（12）O（35）]^10- ring, were isolated from the same reactant NH4VO3 under different conditions. The [CuL]^2＋ bridges the [V10O28]6- clusters to form a two-dimensional sheet in 2, and link the [V6O（18）]^6- rings in 1 and [V（12）O（35）]^10- rings in 3 into three-dimensional frameworks, respectively.

pH-Dependent Assembly of Hybrid Materials Based on Molybdates and Copper/imidazole Complexes

Three novel inorganic-organic hybrid materials, [Cu（imi）2（H2O）（MoO4）]n 1, [Cuz（imi）3（MoO4）E]n.nH2O 2 and [Cu3（imi）2（OH）2（MoO4）2]n 3 （imi = imidazole）, were synthesized and characterized by X-ray single-crystal structure determination. 1 crystallizes in orthorhombic, space group Pca21 with a = 13.382（4）, b = 8.527（2）, c = 9.622（3）A, V = 1098.0（5） A^3 Z = 4, C6H10CuMoN4O5, Mr = 377.66, Dc = 2.285 g/cm^3, F（000） = 740,μ（MoKa） = 3.095 mm^-1, the final R = 0.0256 and wR = 0.0722 for 1896 observed reflections with I 〉 2σ（I）. 2 crystallizes in monoclinic, space group P2t/c with a= 11.170（2）, b = 7.8244（15）, c = 22.631（4）A, β = 115.790（7）°, V = 1780.9（6）A^3 Z = 4, C9H14Cu2Mo2N6O9, Mr = 669.24, Dc= 2.496 g/cm^3, F（000）=1295,μ（MoKa） = 3.792 mm^-1, the final R = 0.0225 and wR = 0.0615 for 3838 observed reflections with I 〉 2σ（I）. 3 crystallizes in monoclinic, space group P21/c with a = 5.5599（19）, b = 23.771（8）, c = 7.3044（18）A , β = 129.356（16）°, V = 746.5（4）A^3, Z = 2, C6H10Cu3Mo2N4O10, Mr = 680.71, Dc = 3.029 g/cm^3, F（000） = 650,μ（MoKa） = 5.900 mm^-1, the final R = 0.0215 and wR = 0.0524 for 1620 observed reflections with I 〉 2σ（I）.

SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS

Mesoporous poly(styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis was achieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymer in the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template or pore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder X-ray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m(2)/g) and pore volumes (e.g. 0.6 cm(3)/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, pore volumes and pore diameters of the hybrid materials increase.

Synthesis and Characterization of Two New Photochromic Inorganic-organic Hybrid Materials Based on Keggin-type Polyoxometalates

Two new photochromic inorganic-organic hybrid materials formed from Keggin-type polyoxometalates（POMs） and metronidazole （C6H9N3O3, MNZ）, formulated as H3PMo12OaO-3MNZ·3H2O （1） and H3PW12O40.3MNZ·3H2O（2）, were synthesized and characterized by elemental analysis, IR spectra, electronic spectra, electron spin resonance （ESR） spectra and thermogravi-metry-differential thermal analysis （TG-DTA）. Reflectance spectra show the presence of weak intermolecular charge transfer between the organic and inorganic moieties in the solid state. The photochromic properties were studied by solid diffuse reflectance spectra and ESR spectra, and the photochromic reactions were found to exhibit first-order kinetics. TG-DTA showed that two hybrid materials have similar thermal behavior.

A New Method to Study the Sol-gel Transition Process of Organic/Inorganic Hybrid Materials

The sol-gel transition process of PMMA/SiO2 hybrid materials was first studied by means of the dynamic torsional vibration method. The different stages of the transition can be described by the change of torque. The temperature-dependent measurement of the gel time（ tg ） gives the possibility to determine the apparent activation energy.（ Ea ） of this transition according to Flory＇s gelation theory. The non-equilibrium thermodynamic fluctuation theory was used to predict the transition behavior. The isothermal transition experiments on hybrid sols with different TEOS（tetraethyl orthosilicate） contents were carried out. The results show that the Ea of a hybrid sol is higher than that of a non- hybrid sol of a TEOS-water-ethanol system. The increasing of TEOS content in a hybrid sol has no obvious effect on the Ea value, but it can enhance the sol-gel .reaction rate.

Polymer-based hybrid materials and their application in personal health

With unprecedented properties and functions,polymer-based hybrid materials hold extremely important position in many fields.Here in this review,we summarized applications of polymer-based hybrid materials toward personal health.Firstly,theoretical calculation and in-situ visualization used to explore the interfacial interaction and formation of hybrid materials are introduced.Secondly,applications of polymer-based hybrid materials in personal health from proactive protection(anti-bacteria and harmful gas removal),health condition monitoring(breathing and sleep)to disease diagnosis(magnetic resonance imaging),and tissue therapy(dental restoration)are discussed.Additionally,aggregation-induced emission(AIE)organic molecules based optical sensors for personal security and polymer semiconductor for organic thin film transistors are simply discussed.Finally,we present the future tendency for preparing polymer-based hybrid materials that related with personal health.

Luminescence properties of rare earth complexes bonded to novel mesoporous spherical hybrid materials

YVO_(4):Eu^(3+) phosphors have been widely used in optoelectronic integration fields of its chemical and thermal stability.However,the excitation spectrum band of VO_(4)^(3-) is too narrow for high-efficiency luminescence,restricting its further development.Herein,flower-like and linear-like YVO_(4):Eu^(3+) hollow mesoporous spheres were synthesized and connected with Eu organic ligand,to obtain a new hybrid luminescent material.The characterization shows that the pores of microspheres are in size of about 2-50 nm,sticked with regular morphology,well crystallized,and in uniform distribution.The emission intensity of hybrid luminescent material is higher than that of single YVO_(4):Eu^(3+) and single Eu co mplexes realizing the purpose of mutually reinforcing luminesce nce.This paper provides a new idea to connect rare earth complexes for a new non-silicon-based mesoporous spherical matrix.

Nanocellulose-Graphene Hybrids: Advanced Functional Materials as Multifunctional Sensing Platform

Naturally derived nanocellulose with unique physiochemical properties and giant potentials as renewable smart nanomaterials opens up endless novel advanced functional materials for multi-sensing applications.However,integrating inorganic functional two-dimensional carbon materials such as graphene has realized hybrid organic-inorganic nanocomposite materials with precisely tailored properties and multi-sensing abilities.Altogether,the affinity,stability,dispersibility,modification,and functionalization are some of the key merits permitting their synergistic interfacial interactions,which exhibited highly advanced multifunctional hybrid nanocomposites with desirable properties.Moreover,the high performance of such hybrids could be achievable through green and straightforward approaches.In this context,the review covered the most advanced nanocellulose-graphene hybrids,focusing on their synthetization,functionalization,fabrication,and multi-sensing applications.These hybrid films exhibited great potentials as a multifunctional sensing platform for numerous mechanical,environmental,and human bio-signals detections,mimicking,and in-situ monitoring.

Hierarchical porous cellulose/lanthanide hybrid materials as luminescent sensor

Photoluminescent hybrid materials containing carboxymethyl cellulose and lanthanide ions（Eu3＋, Tb3＋）were prepared by a facile method under ambient conditions. Lanthanide ions were covalently grafted to the cellulose framework through coordination with the carboxylic groups of the cellulose. Hybrid materials were fabricated as hydrogel and aerogel. As shown by SEM and pore parameters, aerogel materials which were obtained by supercritical CO2 drying show hierarchical porous structure. The photoluminescence spectrum of the hybrid materials shows the characteristic red emission of Eu3＋ ion and green emission of Tb3＋. Further luminescent investigations reveal that these hybrid materials can detect Fe3＋ with relative selectivity and high sensitivity, which suggests that the hybrid materials could be a promising luminescent probe for selectively sensing Fe3＋ ion.

SYNTHESIS AND BIOTECHNOLOGICAL APPLICATIONS OF VINYL POLYMERINORGANIC HYBRID AND MESOPOROUS MATERIALS

We describe the sol-gel synthesis of a new family of organic-inorganic hybrid materials, in which various vinyl polymers are covalently bonded to and uniformly distributed in inorganic oxide matrices. The materials can be tailored to have both good toughness and hardness while maintaining excellent optical transparency. Doping the sol-gel metal oxides with optically active compounds such as D-glucose results in new optical rotatory composite materials. Removal of the dopant compounds from the composites affords mesoporous oxide materials; which represents a new, nonsurfactant-templated route to mesoporous molecular sieves. We have successfully immobilized a series of enzymes and other bioactive agents in mesoporous materials. Catalytical activities of the enzyme encapsulated in mesoporous materials were found to be much higher than those encapsulated in microporous materials.

Multifunctional SnO2/3D graphene hybrid materials for sodium-ion and lithium-ion batteries with excellent rate capability and long cycle life

SnO2 is a promising material for both Li-ion and Na-ion batteries owing to its high theoretical capacities. Unfortunately, the electrochemical performance of SnO2 is unsatisfactory because of the large volume change that occurs during cycling, low electronic conductivity of inactive oxide matrix, and poor kinetics, which are particularly severe in Na-ion batteries. Herein, ultra-fine SnO2 nanocrystals anchored on a unique three-dimensional （3D） porous reduced graphene oxide （rGO） matrix are described as promising bifunctional electrodes for Li-ion and Na-ion batteries with excellent rate capability and long cycle life. Ultra-fine SnO2 nanocrystals of size -6 nm are well-coordinated to the graphene sheets that comprise the 3D macro-porous structure. Notably, superior rate capability was obtained up to 3 C （1In C is a measure of the rate that allows the cell to be charged/discharged in n h） for both batteries. In situ X-ray diffractometry measurements during lithiation （or sodiation） and delithiation （or desodiation） were combined with various electrochemical techniques to reveal the real-time phase evolution. This critical information was linked with the internal resistance, ion diffusivity （DLi＋ and DNa＋）, and the unique structure of the composite electrode materials to explain their excellent electrochemical performance. The improved capacity and superior rate capabilities demonstrated in this work can be ascribed to the enhanced transport kinetics of both electrons and ions within the electrode structure because of the well-interconnected, 3D macro-porous rGO matrix. The porous rGO matrix appears to play a more important role in sodium-ion batteries （SIBs）, where the larger mass/radius of Na-ions are marked concerns.

Optical Waveguides from Organic/Inorganic Hybrid Materials

Organic/inorganic material has attracted great attentions because its importance as photonic materials. We report on our recent results on organic/inorganic hybrid sol-gel materials and optical waveguides like splitter, thermo-optic switch and micro-cavity laser.

Fabrication of 2×2 Thermo-Optic Switches with Organic-Inorganic Hybrid Materials Prepared by Sol-Gel Technique

2×2 Mach-Zehnder interferometric thermo-optic switch was fabricated with organic/inorganic hybrid materials by sol-gel technique and direct UV patterning. The switching time of device was measured to be 4.2 ms and switching power 9.3 mW.

In situ preparation of visible-light-driven carbon quantum dots/NaBiO3 hybrid materials for the photoreduction of Cr(Ⅵ)

In this study,different carbon quantum dots(CQDs)/NaBiO3 hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively.These hybrid materials exhibit an enhanced photocatalytic reduction of hexavalent chromium(Cr(Ⅵ))in the aqueous medium.Zero-dimensional nanoparticles of CQDs were embedded within the two-dimensional NaBiO3 nanosheets by the hydrothermal process.Compared with that of the pure NaBiO3 nanosheets,the photocatalytic performance of the hybrid catalysts was significantly high and 6 wt.%CQDs/NaBiO3 catalyst exhibited better photocatalytic performance.We performed the first-principles density functional theory calculations to study the interfacial properties of pure NaBiO3 nanosheets and hybrid photocatalysts,and confirmed the CQDs played an important role in the CQDs/NaBiO3 composites.The experimental results indicated that the enhanced reduction of Cr(Ⅵ)was probably due to the high loading of CQDs(electron acceptor)on NaBiO3,which made NaBiO3 nanomaterials to respond in visible light and significantly improved their electron-hole separation efficiency.

Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

Layered double hydroxides(LDH)frameworks have shown significant enhancement in stability and reusability,and their tailorable architecture brings new insight into the development of the next generation of hybrid materials,which attracted considerable attention in many fields over the years.One of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition,which can accommodate a wide spectrum of potential anionic guests.This exceptional property makes the LDH system simple to adjust for various applications.However,most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating systems.In this study,LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation(PEO)treatment in the presence of ethylenediaminetetraacetic acid,thereby avoiding the use of hydrothermal autoclave conditions.This LDH system was compared with a hybrid architecture consisting of organic-inorganic self-assembly.An organic layer was fabricated on top of the LDH film using 4-Aminophenol(Aph)compound,resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion performance.At the molecular level,the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as follows.First,Localized orbit locator(LOL)-πisosurface,electrostatic potential(ESP)distribution,and average local ionization energy(ALIE)on the molecular surface were used to highlight localization region,reveal the favorable electrophilic and nucleophilic attacks,and clearly explore the type of interactions that occurred around interesting regions.Second,first-principles based on density functional theory(DFT)was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual interactions.The experimental and computational analyses suggest that the highπ-electron density and delocalization characteristics of the functional groups and benzene ring in the Aph molecule played a leading role in the synergistic effects arising from the combination of organic and inorganic coatings.This work provides a promising approach to design advanced hybrid materials with exceptional electrochemical performance.

Photoelectrochemical properties of MWCNT-TiO_2 hybrid materials as a counter electrode for dye-sensitized solar cells

The MWCNT-Ti02 hybrid materials were prepared by a simply mixing method and used as a counter electrode （CE） for dye-sensitized solar cells. Compared with the platinum CE, MWCNT-TiO2 CE has the similar redox voltage and current response in the cyclic voltammetry. The electrochemical catalytic activity was characterized by the electrochemical impedance spectroscopy and Tafel curve, including the equivalent circuit, the exchange current density, the limiting diffusion current density, and the diffusion coefficient of triiodide/iodide redox species. The results indicate that the reduction process from triiodide to iodide is determined by the kinetic-controlled and diffusion-limited processes. The device performance is optimal based on the MWCNT-TiO2 （mass ratio of 2：1） CE, such as the open-circuit voltage of 0.72 V, the short-circuit photocurrent density of 15.71 mA/cm2, the fill factor of 0.68, and the photon-to-electron conversion efficiency of 7.69%.

Hybrid graded element model for transient heat conduction in functionally graded materials

This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.

SYNTHESIS OF HYBRID MESOPOROUS POLYSTYRENE-SILICA MATERIALS WITH NON-SURFACTANT CITRIC ACID AS TEMPLATE VIA SOL-GEL PROCESS

Hybrid mesoporous polystyrene-silica materials were successfully prepared through HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and triethoxysilyl-functionalized polystyrene obtained via atom transfer radical polymerization (ATRP) of styrene, in the presence of citric acid (CA) as non-surfactant template or pore-forming agent and followed by ethanol extraction to remove template molecules. The materials were characterized by infrared spectroscopy OR), N-2 adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The results indicate that the materials prepared with 50 wt%-60 wt% template contents have average pore sizes of 2-3 nm and large surface areas (ca. 886 m(2)/g) as well as high pore volumes (ca. 0.53 cm(3)/g). The mesoporosity arises from interconnected channels and pores with disordered arrangements. The pore diameters and pore volumes increase as the template content is increased. The pore diameters show a little change upon heating at 200degreesC overnight. However, the materials do not have good hydrothermal stability.

Sonochemical Synthesis of Graphene Oxide-Wrapped Gold Nanoparticles Hybrid Materials:Visible Light Photocatalytic Activity

Graphene oxide(GO)-wrapped gold nanoparticles(Au NPs)hybrid materials are constructed via one-pot sono-chemical synthesis and self-assembly,using ethylene glycol as the reducing agent.The synthesis process above took only 1 h,and the obtained hybrid materials exist as spheres wrapped with gauze-like GO sheets via ionic in-teraction-based self-assembly.The GO sheets are helpful for the well dispersion of the Au NPs.Furthermore,these materials possess enhanced photocatalytic activity under visible light irradiation,owing to the synergistic effect of the two components in the hybrid materials.Our work may provide a convenient approach to control the size and morphology of the Au NPs for the synthesis of GO-wrapped hybrid materials,which opens up a feasible way to synthesize metal NPs/GO composites.Moreover,this method might lead to developing of a broad class of new functionalized materials wrapped with GO sheets.