For studying gas-sensitive materials of gas sensor which is suitable for motoring the characteristic gas in the transformer oil

the adsorption mechanism of two-dimension material with a kind of transition metal to the gas characteristic of transformer oil is studied on the basis of density universal function. First

a Mn-doped SnS two-dimensional material model is set u

p

and the adsorption model of six characteristic gases (H

2

CO

CH

4

C

2

H

2

C

2

H

4

C

2

H

6

) on the modified two-dimensional material are calculated. It is found by analyzing the adsorption energy and adsorption distance that the adsorption energy of the such three gases as CO

C

2

H

2

and C

2

H

4

is larger and the adsorption distance is closer

showing stronger adsorption characteristics. While the adsorption energy of such three gases as H

2

CH

4

and C

2

H

6

is small

and the adsorption distance is longer

showing typical physical adsorption. Furthermore

the chemical mechanism of absorption is analyzed by the both density of state and frontier orbital analysis

finding that the the adsorption of such three kinds of gases as CO

C

2

H

2

and C

2

H

4

significantly changed the electronic structure of the system

showing positive overlap population density of states in the occupied orbital energy levels. At the same time

orbital coupling is formed on the frontier orbital

indicating that the adsorption process of these three characteristic gases is chemical interaction. However

the H

2

CH

4

and C

2

H

6

do not show significant orbital coupling and electronic structure change

and they are mainly physical adsorption dominated by Van Der Waals forces. Finally

the variation in conductivity and desorption time of the Mn-doped SnS two-dimensional material are analyzed through the energy gap and adsorption energy

finding that the material is a kind of gas-sensing material with excellent performance and the possibility of its application in detecting such characteristic gases as CO

C

2

H

2

and C

2

H

4

of the transformer oil.