RESUMEN
CONTEXT: The performance of pristine and Pd-doped WO3 acetone gas sensors is calculated theoretically and compared with available experimental results. Temperature, humidity, and acetone concentration variation are considered in the present work. Transition state theory calculates Gibbs free energy of transition, including its components enthalpy and entropy of transition or activation. The variation of Pd doping concentration is used to obtain the maximum response and lowest response time for the optimum performance of the gas sensor. The present theory considers the reduction of acetone gas concentration as acetone reaches its autoignition temperature. Acceptable agreement between theory and experiment is obtained. The acceptance includes the decrease of Gibbs free energy with doping percentage, variation of temperature exponent to the power twelve in the considered reactions, and reduction of response time with the increase of temperature. METHODS: Density functional theory at the B3LYP level is used. 6-311G** basis set (for O atoms) and SDD (for heavy Pd and W atoms) are used to optimize the structures examined in the present work. The Gaussian 09 program and accompanying software were used to perform the current tasks.
RESUMEN
CONTEXT: In this work, we explore the potential of 2D materials, particularly graphene and its derivatives, for eco-friendly electricity generation and air pollution reduction. Leveraging the significant surface area of graphene nanomaterials, the susceptibility of these graphene-based nanostructures to hazardous substances and their applicability in clean solar cell (SSC) devices were systematically investigated using density functional theory (DFT), as implemented within Gaussian 5.0 code. Time-dependent DFT (TD-DFT) was employed to characterize the UV-visible spectrum of unstrained nanostructures. Herein, we considered three potentially harmful gases-CO, NH3, and Br2. Adsorption calculations revealed a notable interaction between the pure graphene nanostructure and Br2 gas, while the S-doped counterpart exhibited reduced interaction. Saturated S-doped nanostructures demonstrated an enhanced affinity for NH3 and CO gases compared to their pure S-doped counterparts, attributed to the sulfur (S) atom facilitating gas molecule binding to the nanostructure's surface. Furthermore, simulations of the SSC device architecture indicated the superior performance of the pure graphene nanostructure in terms of light-harvesting efficiency, injection energy, and electron injection into the lower conduction band of CBM titanium dioxide (TiO2). These findings suggest a potential avenue for developing nanostructures tailored for SSC devices and gas sensors, offering a dual solution to address air pollution concerns. METHODS: Density function theory was used to compute the ground and excited state properties for pure and sulfur-doped graphene nanostructures. The hybrid function B3LYP with a 6-31G* basis set was utilized to describe the exchange correlation. Gauss Sum 2.2 software is used to estimate the density of state (DOS) for all structures under investigation.
RESUMEN
CONTEXT: In the present work, we investigated the adsorption mechanism of natural sodium (Na), potassium (K), and lithium (Li) atoms and their respective ion on two nanostructures: boron-nitride nanotubes (BNNTs) and beryllium-oxide nanotubes (BeONTs). The main goal of this research is to calculate the gain voltage for Na, K, and Li ionic batteries. Density function theory (DFT) calculations indicated that the adsorption energy between Na + is higher than that of the other cations, and this is particularly clear in the BeONT. Furthermore, gain voltage calculations showed that BNNTs generate a higher potential than BeONTs, with the most significant difference observed in BNNT/Na + . This research provides theoretical insights into the potential uses of these nanostructures as anodes in Na, K, and Li-ion batteries. METHOD: Density function theory used to compute the ground state properties for BeONT and BNNT with and without selected atoms and their ions (Li, K, and Na). B3LYP used for exchange correlation between electrons and ions, and 6-31G* basis set used for all atoms and ions. Gauss Sum 2.2 software used for estimate the density of state (DOS) for all structure under investigation.