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GaN is an emerging 2D material with a wide direct bandgap and high carrier concentration. By using computational methods to introduce Ga defects in GaN, we have made a structure with extremely high chemical activity. After that, Ag, Pt, and Rh are used to repair Ga defects to reasonably suppress the overactive defect sites. In this way, the Ga defect GaN repaired by metal atoms was made. We used density functional theory for dispersion correction for calculation. Specifically, the Perdew–Berke–Ernzerhof generalized gradient approximation method was used. Through the analysis of geometric structure, adsorption energy, electron transfer, deformation charge density, density of states, and band structure, it was screened that Rh@GaN could effectively adsorb SOF2 (adsorption energy −0.78 eV) and be accompanied by a high electron transfer (0.186e). Finally, through the analysis of recovery time and sensitivity, it is verified that Rh@GaN can adsorb SOF2 with high selectivity at room temperature and can generate up to 191.75% response signal to SOF2. [ABSTRACT FROM AUTHOR]

As one of the most important electrical equipment in power system, the stable operation of transformer is the key factor to ensure the safety of power grid system. Winding deformation is the most common fault of transformer, which will seriously affect the reliable operation of the whole power system. Therefore, the detection of transformer winding deformation is of great significance to prevent transformer accidents. In order to further improve the reliability of transformer winding deformation detection, this paper proposes a transformer winding deformation detection method based on oscillation wave method. Firstly, the equivalent circuit model of transformer winding is established, and the transformer winding fault is simulated by changing the inductance and capacitance parameters in the model, and the law between the change of oscillation wave curve and the change of related performance indexes and equivalent parameters is obtained. Finally, the field test verification is carried out on a 10 kV transformer in the laboratory. The results show that the oscillation wave method can diagnose the transformer winding deformation and can be used for the actual transformer winding deformation detection. [ABSTRACT FROM AUTHOR]

With the increasing demand for electricity, voltage measurement has been applied in various fields of the power grid, especially in low-voltage distribution networks and household appliances. However, in low-voltage distribution networks, traditional contact measurement cannot be used due to technical limitations such as the need to damage the insulation layer. Non contact voltage measurement is becoming the main voltage measurement method, A major technical challenge in non-contact measurement is the interference of external electric fields. In order to solve the above problems, this article develops a new type of non-contact low-voltage measurement equipment, which can overcome the interference of external electric fields on measurement and achieve high-precision non-contact voltage measurement. The experimental results indicate that the sensor designed in this paper has high measurement accuracy. The ratio error at power frequency is within ± 0.9%, and the phase error is within 3°. In addition, the sensor also has the advantages of low cost, small size, and convenient manufacturing. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs) are sets of carbon quantum dots derived from graphene or graphene oxide, and they have obvious graphene lattice properties. The number of layers in GQDs is generally no more than five layers, and the diameter size of GQDs is generally less than 10 nm. GQDs have stable photoluminescence characteristics, high specific surface areas, high conductivity levels and adjustable band gaps, and they can be used in sensing systems such as ion detection sensing, optical biosensing, electrochemical biosensing and electronic sensing. Based on the research status of GQDs in recent years and the application background of sensing systems, this review paper focuses on the synthesis strategies, sizes, chemical compositions, crystal structures, optical properties and sensor applications of GQDs. [ABSTRACT FROM AUTHOR]

With the development of two-dimensional materials such as graphene, transition metal dichalcogenides (TMDs), MXenes and MBenes, these materials have received extensive attention from scholars in the field of gas sensing due to their unique and superior properties. Based on first-principles calculations, the adsorption energy, charge transfer, density of states and deformation charge density of CrB, an MBene successfully synthesized under laboratory conditions, were investigated for the adsorption of the decomposition components (CF4, C3F6 and COF2) of an insulating medium, C4F7N. The calculation results revealed strong chemisorption with an adsorption energy as high as −3.336 eV between CrB and COF2, as well as physical adsorption with CF4 and C3F6. However, the excessive interaction strength makes it difficult for COF2 molecules to escape from the binding of the CrB substrate, making CrB more suitable as an adsorbent to remove COF2 gas. Compared with COF2 and CF4, CrB has appropriate adsorption energy and charge transfer for C3F6 adsorption, and its theoretical recovery performance is acceptable, indicating its potential as a sensor for detecting C3F6. [ABSTRACT FROM AUTHOR]