What are the preparation methods and properties of one-dimensional carbide nanomaterials?

Tech 2023-07-05 17:42:58 Source: Network

Canned Green OrangeEditor | Canned Green OrangeCarbides are divided into three types based on their bond types, namely ionic carbides, covalent carbides, and interstitial carbides. Currently, research on one-dimensional carbides mainly focuses on material types, preparation methods, material properties, and related applications

Canned Green Orange

Editor | Canned Green Orange

Carbides are divided into three types based on their bond types, namely ionic carbides, covalent carbides, and interstitial carbides. Currently, research on one-dimensional carbides mainly focuses on material types, preparation methods, material properties, and related applications.

The related applications mainly focus on the fields of field emission devices, catalytic materials, superconducting materials, energy storage materials, and absorbing materials.

Although the types of one-dimensional carbide nanomaterials have been expanded and explored in related applications, overall, there is a lack of systematic summary of research on one-dimensional carbide nanomaterials.

Ionic carbides are generally composed of metal elements and carbon elements with lower Electronegativity and are easy to hydrolyze, such as Calcium carbide, carbonization plating, carbonization, zinc carbide, magnesium carbide, Aluminium carbide, etc.

There are various types of ionic carbides, which can be divided into alkali metal carbides and alkali metal carbides based on different metal elements. According to the different types of carbon bonds, they can be further divided into three categories: ethylcarbides, which contain carbon dumbbell pairs, such as CaC2, Li2C2, and ZnC2.

Methane compounds contain Methanation anions, and allylamine compounds contain allylic ions, such as Mg2C3 and Al4C3.

At present, there is relatively little research on ionic carbides, mainly focusing on their hydrolysis to produce various products. However, research on their formation mechanism, structural morphology, performance applications, and other aspects is not in-depth enough.

Acetylated carbides exhibit polymorphism and exhibit disordered crystal structures at high temperatures. The pressure state during the preparation process is considered to be the inducing factor for the structural transformation of acetylated carbides, and relevant studies have also confirmed this.

At a pressure of about 5GPa, the dumbbell units in Li2C2 are expected to aggregate into serrated carbon atomic chains. We found that monoclinic CaC2 is unstable at pressures above 2GPa, while tetragonal CaC2 may undergo slight structural changes between 10-12GPa.

The pressure during the preparation process affects the final structure of partially acetylated carbides, while Al4C3 is more stable. As a type of ionic carbides, Al4C3 belongs to the allylamine class of compounds with stable properties and no active functions. It has long been used only as a structural material, limiting its application fields. However, research on its properties and applications at the nanoscale has never stopped.

We prepared Al4C3 nanowires coated with a thin layer of Al2O3 through a gas-solid growth mechanism. This type of Al4C3 nanowire structure serves as an electron emission material and has good emission current stability with fluctuations of less than 15%.

In order to better expand the application field of Al4C3 nanowires, Al4C3 and Al4O4C nanowire arrays can be successfully synthesized using a gas-liquid solid growth mechanism and highly oriented pyrolytic stone as a substrate. This allows for large-scale array arrangement of nanowires, providing data support for the application of one-dimensional carbide materials of this type in micro/nano devices, which is of great significance.

In summary, ionic carbides can be classified according to different metal elements or carbon bond types. However, there are few reports on ionic one-dimensional carbide nanomaterials, and further research is needed on the formation mechanism, structural morphology, performance and application of this material.

Covalent carbides, mainly silicon and boron carbides, are Network covalent bonding with carbon atoms bonded to silicon atoms or boron atoms by Covalent bond. Generally, they do not react with water or nitric acid, and are characterized by chemical stability, high melting point and high hardness. For example, silicon carbide (SiC) and Boron carbide (B4C) can be used as refractories and grinding powders.

As a new generation of wide bandgap semiconductor materials, SiC has high strength, high-temperature stability, and excellent thermal conductivity, which can be used for functional ceramics and refractory materials.

One-dimensional silicon carbide nanomaterials not only inherit the properties of SiC, but also possess high toughness, high elastic modulus, high-temperature oxidation resistance, and good optoelectronic properties due to their nanoscale size and structural characteristics. They have broad application prospects in ceramic composites, field effect transistor materials, and electronic and optical nanodevice materials.

So far, the methods for preparing one-dimensional silicon carbide nanomaterials include chemical vapor deposition, carbon nanotube assisted reaction, carbothermal reduction, polymer precursor pyrolysis, and thermal evaporation. The carbon sources we use usually come from traditional fossil carbon sources, which are mostly expensive and cannot be regenerated, which is not conducive to sustainable development.

With the gradual deepening of scientific research, people are gradually turning their attention to nature, hoping to obtain inspiration for material preparation from nature. Plant resources are abundant in nature, with diverse structures and rich elements, making it an ideal green carbon source for synthesizing carbide materials.

Among them, bamboo has unique advantages in many plant materials, such as many varieties, wide distribution and fast growth. It is an environmentally friendly Renewable resource. In addition, bamboo has a hierarchical porous structure, which has adsorption function and can be used as a template.

Researchers successfully prepared SiC nanowire materials using bamboo as a plant template using a one-step carbothermal reduction method. The SiC nanowire prepared by this method has metal catalyst particles at the top, which is a typical VLS growth mechanism.

In summary, whether using bamboo or cotton fibers, the carbon source comes from nature, and inspiration is drawn from nature to prepare this type of carbide nanomaterial, providing a reference for the preparation of other materials.

Further research on this pair of natural materials has found that some of them not only provide carbon sources and structural templates, but also provide the chemical elements required for synthesizing carbides, achieving elemental inheritance, which further expands the use width of natural biomaterials.

For example, rice husk is a typical agricultural waste. Research has found that rice husk itself contains not only a large amount of organic matter, but also a small amount of SiO2 and other inorganic elements, which can be used to produce silicon or carbon based materials.

In addition, we can use rice husks as plant templates and use molten salt assisted electrochemical methods to synthesize SiCNW/C composites in one step without templates. The successful preparation of this composite material indicates that by selecting appropriate natural biomaterials, it is possible to inherit specific elements from natural biomaterials into the prepared material.

The SiCNW/C composite material synthesized using this method also has a special porous structure, which increases the specific surface area of the composite material, facilitates ion conduction and transportation, and exhibits excellent adsorption and catalytic performance.

Interstitial carbides are also called metal carbides, such as Niobium carbide (NbC), Tantalum carbide (TaC), Titanium carbide (TiC), tungsten carbide (WC), silver carbide (Ag2C2), Hafnium carbide (HfC), etc. This type of carbide is ionic bond and Covalent bond.

NbC is one of the most important transition metal carbides, which has attracted great attention due to its excellent properties such as high thermal stability, corrosion resistance, wear resistance, good catalytic performance, high conductivity, and high melting point. It is widely used in heating elements of resistance furnaces and hard alloys.

Carbon thermal method is a common method for preparing one-dimensional NbC nanomaterials. Inspired by natural biodiversity, DU et al. [14] successfully synthesized NbC nanowire arrays using natural bamboo chips as carbon sources and templates, greatly simplifying the synthesis process of NbC nanowires and reducing economic costs. They applied biomaterials for the first time in the process of preparing NbC nanowires, Further validated the feasibility of using natural biomaterials to prepare carbide nanowires.

Based on the excellent electrical performance of NbC nanowires, we can load Pt nanoparticles as high-performance catalysts for Direct methanol fuel cell.

Compared with Pt/C catalyst and Pt/bamboo charcoal catalyst, Pt/NbCNW catalyst has significant catalytic activity. The forward peak current density of its CV curve is 766.1mA/mgPt, which is significantly higher than that of Pt/C catalyst (221.7mA/mgPt) and Pt/bamboo charcoal catalyst (53.5mA/mgPt).

As shown in the figure, the peak potential of Pt/NbCNW catalyst remains stable after 200 cycles, and the peak current density only loses 2.4%, which is much smaller

The above results indicate that NbC nanowires have application value in the field of catalysis, accounting for 19.4% of the loss of Pt/C catalyst and 12.4% of the loss of Pt/bamboo charcoal catalyst.

TiC, as another representative transition metal carbide, has many excellent properties, such as high hardness, low density, high melting point, high elastic modulus, and low thermal expansion coefficient. It is a good conductor of electricity and heat, commonly used in hard alloys and high-temperature materials, and has broad application prospects in catalysis, electronics, and other fields.

Single crystal TiC nanorods were successfully synthesized using cotton fiber as a carbon source and template biological template method. This method has many advantages such as simplicity, convenience, and low cost. The growth mechanism of the prepared TiC nanorods is halide assisted VLS growth mechanism, and the activation energy Ea is measured to be 259kJ/mol, which is similar to most TiC thin filmsEaSimilar.

On this basis, Pt nanoparticles can also be loaded onto TiCNWs using the urea ethylene glycol hydrothermal reduction method. The catalyst Pt/TiCNWs prepared has good electrocatalytic activity, and its peak current density is measured to be 348.3mA/mgPt, which is much higher than the peak current density of Pt/C catalyst (94.1mA/mgPt).

Its corrosion resistance is also outstanding, and after 500 cycles, the electrochemical activity specific surface area of Pt/TiCNWs catalyst remains basically unchanged.

HfC, as a transition metal carbide, is an ultra-high temperature ceramic material with many excellent physical and chemical properties, such as high melting point, high hardness, good chemical stability at high temperatures, low resistivity, good wear resistance, low work function, and field emission stability at high temperatures. It has ideal application prospects in ultra-high temperature anti ablation coatings and high-performance field emitters.

At present, there are various methods for preparing one-dimensional HfC nanomaterials, such as CVD method [38] and precursor polymer pyrolysis method [39],

The CVD method is widely used due to its advantages of simple equipment, convenient operation, and more suitable for field emission applications. TIAN et al. [38] synthesized HfC nanowires using the CVD method, which is a typical VLS growth mechanism.

With the introduction of HfC nanowires, the Thermal diffusivity and thermal conductivity of C/C composites increased by 83.3% and 31.3%, respectively, and the thermal expansion coefficient also increased, showing excellent ablation resistance.

We use a catalyst assisted low-pressure chemical vapor deposition method to vertically grow HfC nanowires on the surface of carbon fibers as carriers for NiCo2O4 nanosheets.

This composite material exhibits a high specific capacitance of 2102F/g, good rate capability (maintaining 85% capacitance at 20A/g), and excellent cycling stability (maintaining 98% capacitance after 5000 cycles at 10A/g) at a current density of 1A/g. It exhibits excellent electrochemical performance and is used as a supercapacitor material.

Transition metal one-dimensional carbides, as the main representative of interstitial one-dimensional carbides, mainly focus on material types, synthesis methods, growth mechanisms, structural characteristics, and related applications. The introduction of natural biomaterials in the synthesis methods has expanded the source of raw materials for this type of material.

The study of the mechanical and electrical properties of a single nanowire provides data support for the practical application of this material.

In addition to the above research, in order to fully achieve the large-scale application of this material, the ordered and controllable large-scale synthesis of this type of one-dimensional carbide can also be considered in the future.

There are three main aspects of research on one-dimensional carbide nanomaterials: the first aspect is to improve the preparation methods, add some new concepts on the basis of existing preparation methods, such as the concept of biomass, and introduce biomaterials as carbon sources and templates to prepare one-dimensional carbide nanomaterials.

The second aspect is to increase the variety of one-dimensional carbide nanomaterials and prepare as many types of one-dimensional carbide nanomaterials as possible by utilizing or improving existing synthesis methods.

The third aspect is to explore the properties and applications of one-dimensional carbide nanomaterials, use existing testing methods to test the microstructure and properties of the prepared one-dimensional carbide nanomaterials, and based on the results, study the possibility of applying them in related fields.

In the future, research on one-dimensional carbide nanomaterials will develop towards the following aspects: low-cost synthesis methods, environmental protection, high efficiency, precise control of material preparation, ordered scaling, single to integrated material properties, and material application theory to practice.

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