gas-sensitive characteristics and applications
Due to surface effect, when the environment changes, the ion valence state of particle on the surface or interface and electronic changes with the change of external environment, can be made sensitive sensors, nanometer alpha Fe2O3 studies have found that they have a good of flammable or toxic gas detection of gas sensitive properties, used for hydrogen, ethanol, carbon monoxide and other toxic gas detection. Zhang et al.  studied the sensing characteristics of ethanol with a human-fe2o3 nanometer material, and found that the reaction time of 50ppni ethanol at 28℃ required only 1s.
electrochemical characteristics and applications
Studies have found that li-fe2o3 nanomaterials can be used as anode materials for lithium ion batteries, and the shape has a great impact on its electrochemical performance. The embedding performance of lithium ions is related to the structure of the crystal, which can be embedded into the inner layer, tunnel, channel, etc. . For nanoscale nano-fe2o3 materials, holes in the crystal surface allow other atoms or molecules, such as lithium ions, to enter. The embedding performance of lithium ions can be better improved by increasing the specific surface area of nanoscale nanopown-fe2o3 material or making it porous. Therefore, many research groups have recently carried out research on the application of nano-fe2o3 materials in lithium ion batteries. Wang et al. prepared a -fe2o3 hollow sphere using the template method and used it as a material for lithium ion electrode. After testing, it was found that its capacitance remained unchanged after 100 cycles of charge/discharge.
magnetic properties and applications
L-fe2o3 is often used as raw material for the synthesis of magnetic materials Fe3O4 and 6-fe2o3, which cannot be directly used as magnetic materials. We know that the magnetism of a material depends on many factors, such as the shape of the material, the size of the material, the crystal structure of the material and so on. Compared with the carbon-fe2o3 of block materials, carbon-fe2o3 at the nanometer level often exhibits unusual magnetic behavior due to its different morphology and particle size. Recent work suggests that there may be some strong dependence on the magnetic properties of g-fe2o3 nanomaterials on their morphology and structure, which may have important significance for further understanding the source and mechanism of magnetism. [19-23]
catalytic characteristics and applications
Carbon-fe2o3, a semiconductor material, has attracted increasing attention from researchers both inside and outside U as a photocatalyst. Qiu  people such as the size prepared by microwave-assisted hydrothermal method is about 5 nm alpha Fe2O3 nanoparticles, used in catalytic CO, 2 – propanol into CO2, it is found that when the gas flow rate for 10 min – 1, reaction temperature reaches 170 ℃ can make CO completely into the CCh, even if the reaction yield remain unchanged after 16 h, and after the catalytic reaction of alpha Fe2O3 nanomaterials characterized by TEM, found that alpha Fe2O3 hardly changes in morphology of nanomaterials, It indicates that the catalytic reaction system with Fe2O3 has maintained good stability. Wang et al.  photocatalyzed the degradation of red storage T and mollification yellow with scavenging -fe2o3 nanoparticles, and the results showed that the scavenging -fe2o3 nanoparticles had a good catalytic degradation function on both of them.
conclusions and prospects
In addition to the previously mentioned oxidation precipitation, sol-gel method, homogeneous precipitation, microemulsion method, forced hydrolysis, hydrothermal method, boiling reflux hydrolysis, microwave hydrolysis, the preparation of ferric oxide nano-powder methods, including air oxidation method, template method, reverse extraction method, etc. The above methods of preparing ferric oxide nanometer powder have advantages and disadvantages: forced hydrolysis method has low hydrolysis concentration and requires high energy consumption under boiling; Nanometer oxidized powders prepared by homogeneous precipitation and oxidized precipitation have mild reaction conditions, low cost, and are easy to be industrialized. Although colloidal chemistry method can effectively prevent the particles from accumulating, but this method of organic solvents flammable, toxic, high product cost; Microemulsion method has low energy consumption, easy operation, good dispersion, interfacial and stability, and is easy to control particle size compared with other methods. Therefore, it is necessary to select a suitable method to prepare ferric oxide nanometer powder, and further study the preparation method with simple process equipment and low cost. Nanometer ferric oxide has excellent performance and low cost of nanomaterials, and has a broad application and development prospect in photocatalysis, lithium ion batteries, supercapacitors, etc. With the development of science and technology and the urgent demand for synthetic materials, the preparation methods of nano-ferric oxide have been constantly innovative, and various methods have been cross-permeating, drawing on each other’s strengths to make up for each other’s weaknesses, and strive to produce nano-ferric oxide particles with excellent performance.