Adsorption properties of Cr modified GaN monolayer for H2, CO, C2H2 and C2H4

Adsorption Mechanism of SO2 on Transition Metal (Pd, Pt, Au, Fe, Co and Mo)-Modified InP3 Monolayer

Using the first-principles theory, this study explored the electronic behavior and adsorption effect of SO2 on an InP3 monolayer doped with transition metal atoms (Pd, Pt, Au, Fe, Co and Mo). Through calculation and analysis, the optimum doping sites of TM dopants on the InP3 monolayer were determined, and the adsorption processes of SO2 by TM-InP3 monolayers were simulated. In the adsorption process, all TM-InP3 monolayers and SO2 molecules were deformed to some extent. All adsorption was characterized as chemical adsorption, and SO2 acted as an electron acceptor. Comparing Ead and Qt, the order of the SO2 adsorption effect was Mo-InP3 > Fe-InP3 > Co-InP3 > Pt-InP3 > Pd-InP3 > Au-InP3. Except for the Au atom, the other five TM atoms as dopants all enhanced the adsorption effect of InP3 monolayers for SO2. Furthermore, the analysis of DCD and DOS further confirmed the above conclusions. Based on frontier orbital theory analysis, it is revealed that the adsorption of SO2 reduces the conductivity of TM-InP3 monolayers to different degrees, and it is concluded that Pd-InP3, Pt-InP3, Fe-InP3 and Mo-InP3 monolayers have great potential in the application of SO2 resistive gas sensors. This study provides a theoretical basis for further research on TM-InP3 as a SO2 sensor.

Pd-GaSe and Pd3-GaSe Monolayers: Two Promising Candidates for Detecting Dissolved Gases in Transformer Oil

In this paper, the adsorption behaviors of three gases (H2, CO, and C2H2) decomposed by the transformer oil on Pd-GaSe and Pd3-GaSe monolayers were calculated by density functional theory. Compared with Pd single-atom doping, Pd3 cluster doping changed the original structure and charge distribution to a greater extent, and more obviously improved the conductivity. According to the analysis of adsorption energy, charge transfer and deformation charge density, the results show that the two doped structures have better adsorption performance for the three gas molecules (H2, CO, and C2H2) than the intrinsic GaSe monolayer. Compared with Pd-GaSe, Pd3-GaSe showed stronger adsorption property for the three gases. Analysis of frontier molecular orbitals and recovery characteristics shows that Pd3-GaSe can be used as an ideal gas sensitive material for H2 detection because of its good desorption properties and obvious conductivity changes. Pd-GaSe can be used as a disposable resistive sensor for CO. Pd3-GaSe is a kind of sensing material suitable for disposable resistance sensors for CO and C2H2. These two doped structures have great application potential in gas adsorption and detection, and provide indications for further study on gas sensor detection by means of metal-doped GaSe monolayer.

A model of FeN-decorated BeO layer particle for CO gas adsorption

Carbon monoxide (CO) is known as a deathful gas produced by burning of hydrocarbons in a lack of enough oxygen, in which breathing CO leads to serious issues on human life health quality. Therefore, adsorption of CO gas is an essential task for diagnosis or removal of this dreadful gas in environment. To do this, a HEME-like model of iron-nitrogen-doped beryllium oxide (FeNBeO) monolayer was investigated for adsorbing CO gas by performing density functional theory (DFT) calculations. Two models were obtained for this process, in which relaxation of CO with C-head or O-head towards Fe region of monolayer. The results indicated that the formation of FeNBeO-CO model could be achieved more favorable than the formation of FeNBeO-OC model. The obtained optimized geometers and energies all approved this achievement for favorability of FeNBeO-CO model formation. Moreover, molecular orbital based electronic features indicated variations of such features for the models upon adsorption of CO substance, in which the models could be detectable in a sensor function for the existence of CO gas in the environment. As a consequence, the investigated FeNBeO monolayer could be proposed useful for adsorption of CO gas at least for the CO deathful gas diagnosis purposes.

Adsorption Characteristics of Carbon Monoxide on Ag- and Au-Doped HfS2 Monolayers Based on Density Functional Theory

A large amount of power equipment works in closed or semi-closed environments for a long time. Carbon monoxide (CO) is the most prevalent discharge gas following a fault in the components. Based on the density functional theory of first principles, the adsorption behavior of CO gas molecules on intrinsic, Ag-doped and Au-doped hafnium disulfide (HfS2) monolayers was systematically studied at the atomic scale. Firstly, the intrinsic HfS2 monolayer, Ag-doped HfS2 (Ag-HfS2) monolayer and Au-doped HfS2 (Au-HfS2) monolayer, with different doping sites, were created. The structural stability, dopant charge transfer, substrate conductivity and energy band structure of different doping sites of the Ag-HfS2 and Au-HfS2 monolayer structures were calculated. The most stable doping structure was selected with which to obtain the best performance on the subsequent gas adsorption test. Then, the CO adsorption models of intrinsic HfS2, Ag-HfS2 and Au-HfS2 were constructed and geometrically optimized. The results show that the adsorption energy of the Ag-HfS2 monolayer for CO gas is −0.815 eV, which has good detection sensitivity and adsorption performance. The adsorption energy of CO on the Au-HfS2 monolayer is 2.142 eV, the adsorption cannot react spontaneously, and the detection sensitivity is low. The research content of this paper provides a theoretical basis for the design and research of gas sensing materials based on HfS2, promoting the development and application of HfS2 in gas sensing and other fields.

Adsorption and Sensing Properties of Dissolved Gas in Oil on Cr-Doped InN Monolayer: A Density Functional Theory Study

Dissolved gas analysis (DGA) is recognized as one of the most reliable methods in transformer fault diagnosis technology. In this paper, three characteristic gases of transformer oil (CO, C2H4, and CH4) were used in conjunction with a Cr-decorated InN monolayer according to first principle calculations. The adsorption performance of Cr–InN for these three gases were studied from several perspectives such as adsorption structures, adsorption energy, electron density, density of state, and band gap structure. The results revealed that the Cr–InN monolayer had good adsorption performance with CO and C2H4, while the band gap of the monolayer slightly changed after the adsorption of CO and C2H4. Additionally, the adsorption property of the Cr–InN monolayer on CH4 was acceptable and a significant response was simultaneously generated. This paper provides the first insights regarding the possibility of Cr-doped InN monolayers for the detection of gases dissolved in oil.