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The radiation shielding properties of different samples of borate-tellurite glass were investigated using WO3 modifiers. Geometric optimization and modification of pristine borate-tellurite with WO3 were carried out based on density functional theory calculations using plane wave basis sets and pseudo-potentials. It was observed that the changes in the physical properties of the white box testing glass (WBTG) systems were determined by WO3 content. Analysis of the linear attenuation coefficient of the sampled glasses, which yielded a value of 7.43 cm for WBTG1 at 20 keV, indicated that WBTG1 was able to stop gamma radiation from Cs-137 and Th-237 sources. Both the µ and µm values were zero above 0.15 MeV, indicating that the WBTG composite was only able to attenuate low-energy photons such as gamma rays. It was found that the characteristic behavior of the WBTG was generally determined primarily by oxygen content, which is in good agreement with theoretical and experimental data. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the capability of CO2 capture by single-walled, carbon-deficient silicon carbide nanotubes (Si12C12-X; X = 1; 2). All calculations of the properties of the investigated systems were performed using density functional theory with plane wave basis sets and pseudopotentials. Electronic interactions were determined using the generalized gradient approximation method in terms of the Perdew-Burke-and Ernzerhof exchange–correlation functional. The analysis of the photoabsorption properties of the investigated systems was based on structural, electronic and optical properties. Analysis of the structural properties revealed that as number of C vacancy increases, bond length decreases, which agrees well with previous literature. Regarding the CO2 overpotential value, both Si12C11:Vc1 and Si12C10:Vc2 showed band edges of -1.5 eV and -1.45 eV, respectively, which are more negative than the standard overpotential value (-1.4 eV) for CO2 reduction. Analysis of the optical absorption spectra revealed good photon absorption by Si12C11:Vc1 (4.16% defect) and Si12C10:Vc2 (8.33% defect) in the visible region accompanied by negligible electron–hole recombination, while pristine SWSiCNT showed absorption in the UV region accompanied by strong electron–hole recombination. This study found that Si12C11:Vc1 and Si12C10:Vc2 are well-suited for CO2 capture and storage, while underlining the CO2 capture capability of pristine SWSiCNT. [ABSTRACT FROM AUTHOR]

Studies of the effects of SiO2 and CO2 absorption on pristine single walled magnesium oxide nanotube (SWMgONT) were done by means of density functional theory. This research considered SiO2 and CO2 gases as our case study because literature studies revealed that SWMgONT acted against CO and NO gases. Based on the results calculated, it has been found that the band gap of SWMgONT is closed as a result of absorption of either SiO2 or CO2 which transformed it from semiconductor state to conductor state. The general decrease in the HOMO–LUMO energy gap of SWMgONT upon absorption of these gases exposes SWMgONT as a promising candidate for sensor applications. In terms of optical absorption, the calculated optical band gap of 2.5 eV which fell in the range 1.2 eV – 2.8 eV exposed the pristine SWMgONT as better photocatalyst. SWMgONT showed higher absorptions with SiO2 and CO2, higher optical refractions and transmissions were also observed as a results of interactions with these gases. So there are significant differences in the absorption spectra for SWMgONT, SiO2MgONT and CO2@MgONT even thou they have the same geometric configurations. The presence of absorption peaks above 2 eV revealed that SiO2@MgONT and CO2@MgONT are potential candidates for the next generations UV–Vis sustainability science and technology such as LED, TMTs and optical lens applications. [ABSTRACT FROM AUTHOR]

This study investigated the photocatalytic properties of MoS 2 -doped boron nitride nanotubes (BNNTs) for overall water splitting using popular density functional theory (DFT). Calculations of the structural, mechanical, electronic, and optical properties of the investigated systems were performed using both the generalized gradient approximation and the GW quasi-particle correction methods. In our calculations, it was observed that only (10, 10) and (12, 12) single-walled BNNTs (SWBNNTs) turned out to be stable toward MoS 2 doping. Electronic property calculations revealed metallic behavior of (10, 10)-MoS 2 -doped SWBNNTs, while the band gap of (12, 12) SWBNNT was narrowed to 2.5 eV after MoS 2 doping, which is within the obtained band gaps for other photocatalysts. Hence, MoS 2 influences the conduction band of pure BNNT and improves its photocatalytic properties. The water-splitting photocatalytic behavior is found in (12, 12) MoS 2 -doped SWBNNT, which showed higher water oxidation (OH - /O 2 ) and reduction (H + /H 2 ) potentials. In addition, optical spectral calculations showed that MoS 2 -doped SWBNNT had an optical absorption edge of 2.6 eV and a higher absorption in the visible region. All of the studied properties confirmed MoS 2 -doped SWBNNT as a better candidate for next-generation photocatalysts for hydrogen evolution through the overall water-splitting process., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)