Adsorption of gas molecules on group III atoms adsorbed g-C3N4: A first-principles study

The first-principles based on density functional theory are used to calculate the adsorption of gas (CO, NO) molecules on group III (B, Al, Ga, In) atoms adsorbed g-C3N4. It is revealed that the B, Al, Ga, and In-g-C3N4 adsorption systems exhibit magnetic semiconducting behavior, while pristine g-C3N4 is a non-magnetic semiconductor. Next, adsorption of the gas molecules on g-C3N4 was investigated. The results show that the charge transfer amount of NO/g-C3N4 is larger than that of CO/g-C3N4. The CO/g-C3N4 system exhibits non-magnetic semiconductor. However, the NO/g-C3N4 system exhibits magnetic semiconductor behavior. Lastly, adsorption of the gas molecules on III-g-C3N4 was also investigated. It is revealed that all gas molecule adsorbed III-g-C3N4 exhibit a magnetic semiconductor. Interestingly, all the gas/III-g-C3N4, except NO/Al-g-C3N4, NO/Ga-g-C3N4, and NO/In-g-C3N4 systems, can promote the charge (electron) transfer from gas molecule to the III-g-C3N4 system, which is conducive to gas sensing. The absorption spectrums of gas molecules adsorbed III-g-C3N4 systems have many strong visible light absorption peaks. Especially, the absorption peak intensity of NO adsorbed In-g-C3N4 system at 436 nm reached 1.19 x 10(5) cm(-1). Thus, above results indicate that the gas molecules adsorption systems will facilitate design of spintronics, gas sensing and high efficiency photocatalytic device.