ABSTRACT
We investigate mechanical, structural and electronic properties of CO2 adsorbed graphitic carbon nitride (g-C3N4) system under biaxial tensile strain via first-principles calculations. The results show that the stress of CO2 adsorbed g-C3N4 system increases and then decreases linearly with the increasing biaxial strain, reaching maximum at 0.12 strain. This is primarily caused by the plane N-C stretching of the g-C3N4. Furthermore, both the Perdew-Burke-Ernzerhof (PBE) and Heyd- Scuseria-Ernzerhof screened hybrid functional (HSE06) band gaps show direct-indirect transitions under biaxial tensile strain and have the maximum also at 0.12 strain. It is found that there is large dipole transition matrix element around Γ point, leading high optical absorption coefficients of the deformed adsorption system, which would be of great use for the applications of new elastic nanoelectronic and optoelectronic devices.
ABSTRACT
We report first-principles calculations on the structural, mechanical, and electronic properties of O2 molecule adsorption on different graphenes (including pristine graphene (G-O2), N(nitrogen)/B(boron)-doped graphene (G-N/B-O2), and defective graphene (G-D-O2)) under equibiaxial strain. Our calculation results reveal that G-D-O2 possesses the highest binding energy, indicating that it owns the highest stability. Moreover, the stabilities of the four structures are enhanced enormously by the compressive strain larger than 2%. In addition, the band gaps of G-O2 and G-D-O2 exhibit direct and indirect transitions. Our work aims to control the graphene-based structure and electronic properties via strain engineering, which will provide implications for the application of new elastic semiconductor devices.
ABSTRACT
According to the disadvantages of current methane sensor in coal mine, the infrared methane concentration detection system based on the principle of infrared spectrum absorption was designed using differential absorption technology. In the system single light beam absorbing cell and single light beam and double wavelengths technology are adopted. Differential amplifier circuit serves as the core of faint signal processing circuit that detects the output signal of methane concentration, and linear formula fits the curve of methane concentration and output voltage, which realizes accurate and full range detection of gas concentration. Experiment shows that measurement error is less than 2%, and the system has very high measurement precision and possesses the basis of industrial applications.
