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Solar photocatalytic hydrogen production is attracting great attention for addressing the environmental and energy challenges, while the low solar-to-hydrogen (STH) efficiency of photocatalysts hinders its industrial implementation. To enhance the STH efficiency, the construction of single-atom photocatalyst and direct Z-scheme heterojunctions (HJs) is deemed as promising strategies. This work has thoroughly studied the photocatalytic properties of WSe 2 /ZrS 2 , GaTe/ZrS 2 van der Waals HJs, as well as these HJs anchored by single atoms (Pt@WSe 2 /ZrS 2 , Pt@GaTe/ZrS 2) using the first-principles calculations. The results indicate that appropriate bandgaps, band edge positions and internal electric field effectively accelerate photogenerated carrier migration via direct Z-scheme path in WSe 2 /ZrS 2 and GaTe/ZrS 2 HJs. After anchoring Pt atoms onto the reducing agent layer of these HJs, the hydrogen evolution performance of both Pt@WSe 2 /ZrS 2 and Pt@GaTe/ZrS 2 systems are significantly enhanced, enabling spontaneous redox reactions. Furthermore, these HJs exhibit excellent light absorption capacity, with their optical absorption spectra even expanding into the near-infrared range. Especially, the STH efficiency of Pt@GaTe/ZrS 2 HJ reaches 12.94%, surpassing the threshold necessary for future industrial applications. Therefore, this study presents a novel strategy for precisely modulating photocatalytic performance and predicts that Pt@WSe 2 /ZrS 2 and Pt@GaTe/ZrS 2 HJs are promising direct Z-scheme systems for overall water splitting. [Display omitted] • A novel strategy is introduced for precisely modulating photocatalytic performance. • WSe 2 /ZrS 2 and GaTe/ZrS 2 heterojunctions possess ideal band edges and band gaps. • Single-atom Pt anchored heterojunctions further enhance hydrogen evolution. • These anchored heterojunctions efficiently harness light from visible to near-infrared. • These heterojunctions are promising Z-scheme photocatalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

CaMnO3 is a promising starting point for the search of perovskites which are suitable as electrode materials for the hydrogen evolution reaction (HER). In a previous theoretical study [Phys. Status Solidi B 2022, 260, 2200427], it was established that the global hybrid functional PW1PW is well suited to obtain structural, energetic, and electronic bulk properties. Herein, the focus is extended to surface properties of CaMnO3. All symmetry‐inequivalent low‐index surfaces of CaMnO3 are investigated with PW1PW. Based on the experience with polar surfaces, it is decided to employ stoichiometric and symmetric models, in some cases with Schottky defects. From the calculated surface energies, the crystal morphologies are predicted based on the Gibbs–Wulff theorem. The (101), (100), (011), (001), and (010) surfaces (space group no. 62) and the (010), (110), (011), and (101) surfaces (space group no. 20) dominate the surfaces of respective single crystals and should be considered in future theoretical calculations of the HER. Furthermore, it is found that the modification with space group no. 20 is significantly more stable than space group no. 62 for nanoparticles with a diameter below 10 nm. [ABSTRACT FROM AUTHOR]

CaMnO3 is a promising starting point for the search of perovskites which are suitable as electrode materials for the hydrogen evolution reaction (HER). In a previous theoretical study [Phys. Status Solidi B 2022, 260, 2200427], it was established that the global hybrid functional PW1PW is well suited to obtain structural, energetic, and electronic bulk properties. Herein, the focus is extended to surface properties of CaMnO3. All symmetry‐inequivalent low‐index surfaces of CaMnO3 are investigated with PW1PW. Based on the experience with polar surfaces, it is decided to employ stoichiometric and symmetric models, in some cases with Schottky defects. From the calculated surface energies, the crystal morphologies are predicted based on the Gibbs–Wulff theorem. The (101), (100), (011), (001), and (010) surfaces (space group no. 62) and the (010), (110), (011), and (101) surfaces (space group no. 20) dominate the surfaces of respective single crystals and should be considered in future theoretical calculations of the HER. Furthermore, it is found that the modification with space group no. 20 is significantly more stable than space group no. 62 for nanoparticles with a diameter below 10 nm. [ABSTRACT FROM AUTHOR]

A computational methodology is briefly described, which appears to be able to accurately describe the mechanisms of redox active enzymes. The method is built on hybrid density functional theory where the inclusion of a fraction of exact exchange is critical. Two examples of where the methodology has been applied are described. The first example is the mechanism for water oxidation in photosystem II, and the second one is the mechanism for N2 activation by nitrogenase. The mechanism for PSII has obtained very strong support from subsequent experiments. For nitrogenase, the calculations suggest that there should be an activation process prior to catalysis, which is still strongly debated. [ABSTRACT FROM AUTHOR]

Sustainable hydrogen production is one of the most important topics in modern energy economics. Of technological relevance are, for example, electrochemical and thermal splitting of water. For such processes anode materials with a variable concentration of oxygen defects are required. Herein, the oxygen defect thermochemistry of a possible anode material, the perovskite CaMnO3, is investigated theoretically. The aim of this work is to identify reliable quantum chemical methods for the calculation of oxygen defect formation enthalpies and entropies, including configuration entropy, which is usually neglected. All possible defect configurations in a supercell are computed to obtain the configuration entropy using Boltzmann statistics. Various generalized gradient approximation (GGA), meta‐GGA, and hybrid functionals as implemented in the solid‐state programs CRYSTAL and VASP are evaluated for the calculation of structure parameters, electronic and magnetic properties, and reaction energies of CaMnO3. The global hybrid functional PW1PW gives the most accurate overall description of CaMnO3 and is therefore recommended for future theoretical studies of more efficient water‐splitting catalysts based on calcium manganate. [ABSTRACT FROM AUTHOR]

The presence of cubic PuH2 and PuH3, the products of hydrogen corrosion of Pu, during long-term storage is of concern because of the materials' pyrophoricity and ability to catalyse the oxidation reaction of Pu to form PuO2. Here, we modelled cubic PuH2 and PuH3 using Density Functional Theory (DFT) and assessed the performance of the PBEsol+U+SOC (0 ≤ U ≤ 7 eV) including van der Waals dispersion using the Grimme D3 method and the hybrid HSE06sol+SOC. We investigated the structural, magnetic and electronic properties of the cubic hydride phases. We considered spin–orbit coupling (SOC) and non-collinear magnetism to study ferromagnetic (FM), longitudinal and transverse antiferromagnetic (AFM) orders aligned in the <100>, <110> and <111> directions. The hybrid DFT confirmed that FM orders in the <110> and <111> directions were the most stable for cubic PuH2 and PuH3, respectively. For the standard DFT, the most stable magnetic order is dependent on the value of U used, with transitions in the magnetic order at higher U values (U > 5 eV) seen for both PuH2 and PuH3. [ABSTRACT FROM AUTHOR]

Boron‐containing III‐nitride heterostructures have recently attracted significant attention for improving the efficiency of visible and UV light emitters. However, the fundamental material properties of wurtzite (WZ) boron nitride (BN) are largely unexplored. Here, highly accurate first‐principles calculations are used to gain insight into internal strain, elastic constants, and electronic band structure deformation potentials. These parameters are key ingredients for simulating, and thus predicting, electronic and optical properties of boron‐containing III‐nitride‐based light emitters. The ab initio calculations show, for instance, that the quasi‐cubic approximation for deformation potentials is a poor approximation for WZ BN. [ABSTRACT FROM AUTHOR]

This work investigates, using density functional theory (DFT), the localization of electrons and holes produced by irradiation in LiF crystals doped with Ti. We show that the Ti can act either as an electron trap, when located at an interstitial position of the LiF lattice, or as a trap for holes by substituting a Li atom. We also observe that an excess electron is localized in a Ti p-state while a hole localizes in a Ti d-state. The localization of the hole in this state when the Ti substitutes a Li is supported by results reported in the literature where it was assumed that the Ti substitute is a hole trap. The defect energy levels obtained in this work agree quite well with those reported in experiments. • Electronic structure calculations of Ti-doped LiF are performed from first principles. • Ti impurity shows a dual character behaving as an electron trap when interstitial and a hole trap when substitutional. • Excess electron is localized in a Ti p-state while a hole localizes in a Ti d-state. [ABSTRACT FROM AUTHOR]

The presence of cubic PuH2 and PuH3, the products of hydrogen corrosion of Pu, during long-term storage is of concern because of the materials’ pyrophoricity and ability to catalyse the oxidation reaction of Pu to form PuO2. Here, we modelled cubic PuH2 and PuH3 using Density Functional Theory (DFT) and assessed the performance of the PBEsol+U+SOC (0 ≤ U ≤ 7 eV) including van der Waals dispersion using the Grimme D3 method and the hybrid HSE06sol+SOC. We investigated the structural, magnetic and electronic properties of the cubic hydride phases. We considered spin–orbit coupling (SOC) and non-collinear magnetism to study ferromagnetic (FM), longitudinal and transverse antiferromagnetic (AFM) orders aligned in the , and directions. The hybrid DFT confirmed that FM orders in the and directions were the most stable for cubic PuH2 and PuH3, respectively. For the standard DFT, the most stable magnetic order is dependent on the value of U used, with transitions in the magnetic order at higher U values (U > 5 eV) seen for both PuH2 and PuH3.

Using hybrid density functional theory calculations, we systematically study the biaxial strain and electric field modulated electronic properties of g-ZnO/SnS 2 , g-ZnO/SnSe 2 , and g-ZnO/SnSSe S-scheme van der Waals heterostructures (vdWHs). g-ZnO/SnS 2 and g-ZnO/SnSSe are found to be promising photocatalysts for water splitting with high solar-to-hydrogen efficiencies, even under acidic, alkaline, and high-stress conditions. The strain effect on the bandgaps of g-ZnO/SnXY is explained in detail according to the correlation between geometry structure and orbital hybridization of SnXY, which could help understand the strain-induced band structure evolutions in other SnXY (X, Y = S, Se)-based vdWHs. It is surprising that under an external electric field, g-ZnO/SnS 2 , g-ZnO/SnSe 2 , and g-ZnO/SnSSe can offer the occupied nearly free-electron (NFE) states. In many materials, NFE states are usually unoccupied and is not conducive to the charge transport. The NFE state in g-ZnO/SnSe 2 is the most sensitive to the electric field and might be promising electron transport channel in nanoelectronic devices. g-ZnO/SnSe 2 might also have application potential in gas sensors and high-temperature superconductors.