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The development of high-performance direct-Z Scheme heterojunctions as photocatalysts is the focus of current research, and it is also an effective way to improve the performance of photocatalysts. Based on this, we use density functional theory (DFT) to predict two-dimensional (2D) XSe2/SiH (X = Zr, Sn) van der Waals (vdW) heterojunction as a potential direct Z-scheme heterojunction photocatalyst. The results indicate that both heterojunctions exhibit a typical Type-II band edge arrangement. Furthermore, the small band gap and built-in electric field of the heterojunctions facilitate electronic transitions between the valence band (VB) and conduction band (CB), thereby increasing the probability of interlayer electron–hole (e−-h+) recombination within the heterojunction. This process is beneficial for the formation of direct-Z Scheme heterojunctions. In addition, the XSe2/SiH (X = Zr, Sn) heterojunction exhibits remarkable photogenerated electron and hole driving forces, along with exceptional light-trapping capabilities. Therefore, XSe2/SiH (X = Zr, Sn) heterojunction is a potential new photocatalyst. [ABSTRACT FROM AUTHOR]

The aggravation of the energy crisis makes it particularly important to develop catalysts that can efficiently enhance visible-light-catalyzed water splitting. We predict the potential of a type II van der Waals (vdW) g-ZnO/Ga2SSe heterostructure as an efficient photocatalyst based on density functional theory and analyze its optoelectronic and structural properties in this study. The results indicate that the g-ZnO/Ga2SSe heterostructure is a direct bandgap semiconductor, and the redistribution of charges on the layer interface will form a weak built-in electric field, which effectively inhibits the recombination of photon–hole pairs and improves the carrier mobility. More deeply, its suitable band gap and band edge positions can meet the requirements of water split oxidation and reduction reactions in the common pH range. This indicates that the g-ZnO/Ga2SSe vdW heterostructure has great potential to become an efficient photocatalyst for water splitting, which can provide a certain basis for the development of novel visible light-catalyzed water splitting catalysts. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysts are hampered by carriers' recombination problems that hinder their practical application. The rational design of direct Z-scheme heterojunctions based on two-dimensional (2D) materials is one of the effective ways to solve this problem. Therefore, we predicted 2D CrS2/boron phosphide (BP) van der Waals heterojunction as a potential direct Z-scheme photocatalyst based on density functional theory. The CrS2/BP heterojunction has a small direct band gap, which is favorable for light absorption. In addition, the built-in electric field promotes the separation and transfer of the desired carriers. Photogenerated electrons and holes are localized in the conduction band of the BP component and the valence band of the CrS2 component, respectively. In addition, it was found that the heterojunction obtained a relatively small band gap and a wide optical absorption range at + 4% and + 5% strains. Therefore, the CrS2/BP heterojunction is a new photocatalyst satisfying the direct Z-scheme charge transfer mechanism, which has a certain application value. [ABSTRACT FROM AUTHOR]

In the field of photocatalytic water splitting, the direct Z-scheme heterostructure is regarded as a promising photocatalyst configuration. In this paper, we use density functional theory to predict the Ti2CO2/CrSSe heterostructure as a potential direct Z-scheme heterojunction photocatalyst and investigate its electronic, optical, and heterojunction interface properties. The results show that the Ti2CO2/CrSSe heterojunction has a strong electrostatic attraction between the electrons in the conduction band of Ti2CO2 and the holes in the valence band of CrSSe due to the small interlayer band gap, which can realize the rapid interlayer electron-hole (e−–h+) recombination. The redistribution of charge results in a built-in electric field that prevents unwanted electron and hole migration. In addition, the Ti2CO2/CrSSe van der Waals (vdW) heterojunction exhibits excellent light absorption, and its redox ability has been improved. These properties indicate that Ti2CO2/CrSSe heterostructure is a promising photocatalyst. [ABSTRACT FROM AUTHOR]

Direct Z-scheme based on biomimetic artificial photosynthesis is a promising strategy to enhance photocatalytic activity. The search for direct Z-scheme photocatalysts is imperative, and the photocatalytic efficiency is mainly influenced by the separation rate of photogenerated electron–hole (e--h+) pairs and the light capture ability. Herein, a two-dimensional (2D) van der Waals (vdW) heterostructure consisting of a monolayer of CrS2 and Sc2CF2 is predicted based on density functional theory (DFT) as a promising direct Z-scheme photocatalyst for water splitting. The CrS2/Sc2CF2 heterojunction possesses a large energy band interleaving arrangement and a small interlayer band gap, and the orientation of the built-in electric field promotes interlayer carrier complexes, with electrons and holes localized at the highest redox energy level, respectively. In addition, the CrS2/Sc2CF2 heterojunction possesses a high overpotential driving force and excellent light harvest ability. Our calculations indicate that the CrS2/Sc2CF2 heterojunction is a promising new photocatalyst. [ABSTRACT FROM AUTHOR]

A triphenylamine-based dye sensitizer–the electron donor, added with the embellishment, was designed and analyzed, to serve as a backup molecule for the sensitized solar cells (DSSCs). For a more realistic performance, five sensitizer molecules (ND, NDSH-1∼4) with triphenylamine (TPA) units as election donors (D), 4-benzo[c] [1, 2, 5] thiadiazol segment as acting as auxiliary acceptors (A), 4-ylethynyl as bridge (π) and benzoic acid as the electron acceptor (A) were explored in dichloromethane solvent by the methods of Density functional theory (DFT) and Time-dependent density functional theory (TD-DFT). Meanwhile, to understand the working process of DSSCs more systematically, these dyes adsorbed on (TiO2)16 were further explored. Finally, the effects of triphenylamine modification are summarized and disclosed from the phenomenon of simulation. The results show that the nitrogen-substituted hexyloxy dye exhibits a very narrow band gap and has a distinct red-shifted absorption band compared to the experimental dye ND. [ABSTRACT FROM AUTHOR]

[Display omitted] • WSeTe/XS 2 (X = Hf, Sn, Zr) heterojunctions have direct Z-scheme band alignment and satisfy overall water splitting. • It has a high light absorption capacity and a wide light absorption range. • Photo-generated carriers interlayer recombine under the action of the built-in electric field. • Under the action of the vertical intrinsic electric field, the redox capacity is further improved. Finding photocatalytic materials with high hydrogen production efficiency is an effective way to solve the problem of the energy crisis. We use density functional theory (DFT) to predict the 2D WSeTe/XS 2 (X = Hf, Sn, Zr) van der Waals (vdW) heterojunctions as the potential direct Z-scheme heterojunction photocatalysts and discuss the mechanism of photocatalytic water splitting under the interaction of vertical intrinsic electric field and built-in electric field. The WSeTe/XS 2 heterojunctions have large band-edge staggered alignment, small interlayer bandgap, and good interlayer carrier recombination, which predict the direct Z-scheme charge transfer path formation. Meanwhile, the small bandgap of the 2D WSeTe/XS 2 direct Z-scheme heterojunctions enables it to obtain a wide light absorption range. The built-in electric field from WSeTe to XS 2 changes the charge transfer mode of the heterojunction and improves the separation efficiency of photo-generated carriers, and the vertical intrinsic electric field not only improves the hydrogen evolution reaction (HER) ability but also reduces the bandgap limitation of photocatalytic materials. In this paper, the 2D WSeTe/XS 2 heterojunctions show significant advantages as photocatalytic materials, providing unique insights for researching and developing this kind of heterojunction. [ABSTRACT FROM AUTHOR]

• Five dihydroindolocarbazole-based organic dyes were investigated with DFT and TD-DFT. • Molecular absorption spectra, charge transfer characteristics, etc., were analyzed. • The changes in dyes' properties before and after absorbing on TiO2 were studied. • Several key parameters were calculated to show the photovoltaic performances. In recent years, organic dye molecules as photosensitizers have played a significant role in the field of dye-sensitized solar cells. In this context, two primary dihydroindolocarbazole-based organic dyes (sk201 and sk202), which were synthesized recently by Song et al., and three further designed dyes (DMZ1-3) were theoretically investigated based on density functional theory and time-dependent density functional theory. Molecular geometries, absorption spectra, charge transfer, molecular electrostatic potential and nonlinear optical properties were quantificationally studied and visually presented to reveal the relationships between the molecular structures and performances of dyes. The effects of joining the isolated dyes and TiO 2 on the molecular absorption spectra and energy levels were analyzed. Moreover, several parameters, such as efficiency of light-harvesting, driving forces of electron regeneration and injection, excited-state lifetime and vertical dipole moment, were calculated to give the multi-angle demonstrations of the photovoltaic performances for these dyes. [ABSTRACT FROM AUTHOR]