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The CO2 conversion to methanol (CO2-to-CH3OH conversion) is a promising way to resolve greenhouse gas emissions and global energy shortage. Many catalysts are of interest in improving the efficiency of the conversion reaction. The PdCo alloy is a potential catalyst, but no research is available to clarify the CO2-to-CH3OH reaction mechanism of this alloy. Here, using density functional theory combined with the thermodynamic model, we elucidated the reaction mechanism of the CO2-to-CH3OH conversion on the Pd-skin/PdCo alloy catalyst via thermo- and electro-catalytic processes. The adsorption of CO2-to-CH3OH intermediates with key stable intermediates such as HCOO, COOH, and CO was explored. Free-energy diagrams for the CO2-to-CH3OH conversion were constructed. We found that the formate pathway is the most favorable one. The charge transfer plays a crucial role in the substrate–adsorbate interaction via electronic structure analysis. This work provides valuable guidance for designing Pd-based catalysts for the CO2-to-CH3OH conversion. [ABSTRACT FROM AUTHOR]

We present a systematic investigation of polyethylenimine (PEI) doping mechanism and its effects on the multilayer MoS2 field effect transistors (FETs). The threshold voltages of MoS2 FETs before (i.e., pristine) and PEI doping are observed at 3.7 and 0.72 V, respectively. This negative threshold voltage shift clearly reveals that the PEI molecules effectively act as n-type dopants. The electrical properties are improved by absorption of PEI molecules onto MoS2 channel because the width of Schottky barrier (SB) is narrowed by the induced interfacial dipole between PEI molecules and MoS2 layers. Through the density function theory (DFT) calculation and X-ray photoelectron spectroscopy (XPS) analysis, we confirm that formation of MoN bond generates new energy state into the bandgap. Consequently, the hole carriers can easily tunnel through the barrier under negative gate voltage. Furthermore, PEI doping improve photoresponsivity and time-resolved photo-switching characteristics because of the new energy state. Our studies demonstrate the PEI doping method has a great potential for improving electrical and optical properties of MoS2-based devices. [ABSTRACT FROM AUTHOR]

We employed Density Functional Theory (DFT) to investigate the electronic, magnetic, and optical characteristics of armchair graphene nanoribbons (AGNRs) decorated with neptunium (Np) and plutonium (Pu). Our analysis delves deeply into the intricate orbital hybridizations associated with C-Np, C-Pu, C-C, Np-Np, and Pu-Pu chemical bonds. Through this approach, we explore the electronic band structure, band-decomposed charge densities, spin-charge distributions, and Van Hove singularities in the density of states. Furthermore, our examination successfully correlates optical excitation with electronic band energy. Our results indicated that these rare-earth atoms are strongly bound to the edge structure of AGNRs, significantly altering their electronic, magnetic, and optical properties. Theoretical exploration not only reveals the intriguing physical and chemical properties of rare-earth (Np/Pu) decorated AGNRs but also presents a practical pathway for synthesizing novel materials., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)

CO 2 capture is a crucial strategy to mitigate global warming and protect a sustainable environment. Metal-organic frameworks with large surface area, high flexibility, and reversible adsorption and desorption of gases are good candidates for CO 2 capture. Among the synthesized metal-organic frameworks, the MIL-88 series has attracted our attention due to their excellent stability. However, a systematic investigation of CO 2 capture in the MIL-88 series with different organic linkers is not available. Therefore, we clarified the topic via two sections: (1) elucidate physical insights into the CO 2 @MIL-88 interaction by van der Waals-dispersion correction density functional theory calculations, and (2) quantitatively study the CO 2 capture capacity by grand canonical Monte Carlo simulations. We found that the 1π g , 2σ u /1π u , and 2σ g peaks of the CO 2 molecule and the C and O p orbitals of the MIL-88 series are the predominant contributors to the CO 2 @MIL-88 interaction. The MIL-88 series, i.e. , MIL-88A, B, C, and D, has the same metal oxide node but different organic linkers: fumarate (MIL-88A), 1,4-benzene-dicarboxylate (MIL-88B), 2,6-naphthalene-dicarboxylate (MIL-88C), and 4,4'-biphenyl-dicarboxylate (MIL-88D). The results exhibited that fumarate should be the best replacement for both the gravimetric and volumetric CO 2 uptakes. We also pointed out a proportional relationship between the capture capacities with electronic properties and other parameters., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Researchers investigated the modification of the LaAlO 3 /SrTiO 3 interface with Au overlayers and nanoparticles, which led to the change of various physical properties. However, no research is available to elucidate insights into the interaction of Au with the LaAlO 3 /SrTiO 3 substrate. Therefore, this study is devoted to solving the question using density functional theory calculations. We also studied the optical properties of the LaAlO 3 /SrTiO 3 system before and after the Au adsorption. We found that an additional optical peak occurs with significant intensity in the wavelength region of 600 nm to 1200 nm depending on the LaAlO 3 film thickness. This peak is attributed to the increase in the hole states in the presence of Au adsorption with the increase in the LaAlO 3 film thickness., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

MoS 2 is one of the well-known transition metal dichalcogenides. The moderate bandgap of monolayer MoS 2 is fascinating for the new generation of optoelectronic devices. Unfortunately, MoS 2 is sensitive to gases in the environment causing its original electronic properties to be modified unexpectedly. This problem has been solved by coating MoS 2 with polymers such as polyethyleneimine (PEI). Furthermore, the application of pressure is also an effective method to modify the physical properties of MoS 2 . However, the effects of polyethyleneimine and pressure on the electronic and optical properties of monolayer MoS 2 remain unknown. Therefore, we elucidated this matter by using density functional theory calculations. The results showed that the adsorption of the PEI molecule significantly reduces the width of the direct bandgap of the monolayer MoS 2 to 0.55 eV because of the occurrence of the new energy levels in the bandgap region due to the contribution of the N-2p z state of the PEI molecule. Remarkably, the transition from semiconductor to metal of the monolayer MoS 2 and the MoS 2 /PEI system occurs at the tensile pressure of 24.95 and 21.79 GPa, respectively. The bandgap of these systems approaches 0 eV at the corresponding pressures. Importantly, new peaks in the optical spectrum of the clean MoS 2 and MoS 2 /PEI appear in the ultraviolet region under compressive pressures and the infrared region under tensile strains., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)