First-principles investigation of CO adsorption on pristine, C-doped and N-vacancy defected hexagonal AlN nanosheets

• Published in: Applied surface science 2018-05, Vol.439, p.196-201
• Main Authors: Ouyang, Tianhong, Qian, Zhao, Ahuja, Rajeev, Liu, Xiangfa
• Format: Article
• Language: English
• Subjects: AlN nanosheet; CO sensing; DFT-D2; Doping; Electronic structure; First-principles
• ISSN: 0169-4332; 1873-5584; 1873-5584
• DOI: 10.1016/j.apsusc.2018.01.040

•Adsorptions of CO on pure and defected h-AlN nanosheets are studied by DFT-D2 method.•C-doping is promising to improve CO detection capability of pure h-AlN monolayer.•N-vacancy design is inferior to C-doping but can also enhance the CO adsorption.•Electronic structure origin has been analyzed to understand the adsorption physics. The optimized atomic structures, energetics and electronic structures of toxic gas CO adsorption systems on pristine, C-doped and N-vacancy defected h-AlN nanosheets respectively have been investigated using Density functional theory (DFT-D2 method) to explore their potential gas detection or sensing capabilities. It is found that both the C-doping and the N-vacancy defect improve the CO adsorption energies of AlN nanosheet (from pure −3.847 eV to −5.192 eV and −4.959 eV). The absolute value of the system band gap change induced by adsorption of CO can be scaled up to 2.558 eV or 1.296 eV after C-doping or N-vacancy design respectively, which is evidently larger than the value of 0.350 eV for pristine material and will benefit the robustness of electronic signals in potential gas detection. Charge transfer mechanisms between CO and the AlN nanosheet have been presented by the Bader charge and differential charge density analysis to explore the deep origin of the underlying electronic structure changes. This theoretical study is proposed to predict and understand the CO adsorption properties of the pristine and defected h-AlN nanosheets and would help to guide experimentalists to develop better AlN-based two-dimensional materials for efficient gas detection or sensing applications in the future.