First-principles Study On Adsorption Behavior Of CH₂O On Typical Two-dimensional Non-carbon Materials

Gas sensors are widely used sensors at present.Gas characteristic information can be transformed into corresponding detectable electrical signal characteristics by gas sensors,so as to achieve the detection of specific gases.With the improvement of people’s living standard and the increasing attention to environmental protection,the detection of various toxic and harmful gases,the monitoring of air pollution,and the detection of food and living environment quality have put forward higher requirements.Formaldehyde is a kind of poisonous gas with colorless and irritating odor,it can be seen almost anywhere in human activities.Therefore,the detection of formaldehyde（CH₂O）is of great significance to people’s production and life.With the successful preparation of graphene,more and more two-dimensional materials have been successfully predicted and prepared.Because of their large surface area and excellent electrical properties,two-dimensional materials have better performance than traditional metal oxides in the field of semiconductor gas sensors（Applications in MEMS and NEMS devices）.The main research content of this paper is to design a nd study semiconductor gas sensors based on two-dimensional materials by first-principles calculation method,especially for the detection of formaldehyde gas.The gas adsorption behavior of CH₂O,CO,CO₂,SO₂,O₂ and NO on the surface of penta-BP₅ has been studied by first-principles calculation method.In summary,the structure and electronic property of penta-BP₅ with adsorbed CH₂O,CO,CO₂,SO₂,O₂ and NO molecules have been investigated by first principles calculations.The results show that CH₂O,CO,CO₂ and SO₂ can be physically adsorbed on the surface of penta-BP₅.Considering that adsorptions of CH₂O and SO₂ on penta-BP₅ have considerable charge transfers and significant influence on the electronic properties of penta-BP₅,penta-BP₅ can be used for detecting CH₂O and SO₂.Besides,the two gases are easy to be removed from penta-BP₅ due to the physical adsorption,indicating that penta-BP₅ may have better performance in detecting these two gases than blue phosphorus.For O₂ and NO,their adsorptions are trend to the chemical adsorption,indicating that penta-BP₅ can be applied for detecting and catalyzing these two gases.In addition,the adsorption behaviors of formaldehyde molecules on monolayer BN,AlN,GaN,InN,BP and P surfaces have been studied by first-principles calculation.In summary,the structure,charge transfers,and electronic characteristics of CH₂O adsorbed on the BN,AlN,GaN,InN,BP,and P monolayers were investigated using first-principles calculations.For the adsorption of CH₂O on the BN,GaN,BP,and P surfaces,the gas adsorption behavior followed the trends of physical adsorption.By assessing the band structures and DOSs of the gas adsorption systems,it was found that the electronic characteristics of these materials were evidently altered by the adsorption of the CH₂O molecule,except for the BP monolayer.The GaN monolayer was considered to be the most suitable material for detecting CH₂O in o ur study because of its appreciable charge transfer and moderate adsorption energy.The adsorption of CH₂O on the surface of the AlN and InN monolayers was obs erved to follow the trends of chemical adsorption,with large charge transfers and considerable adsorption energies,revealing that AlN and InN have excellent pot ential for catalyzing C H₂O or in disposable gas sensors for CH₂O detection.