TM doping modulates p–d orbital coupling to improve the OER performance of the Ni ₃ S ₂ (101) facet.

Hydrogen generation via photoelectrochemical (PEC) overall water splitting is an attractive means of renewable energy production so developing and designing the cost-effective and high-activity bifunctional PEC catalysts both for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) has been focused on. Based on first-principles calculations, we propose a feasible strategy to enhance either HER or OER performance in the monoclinic exposed BiVO₄ (110) facet by the introduction of oxygen vacancies (O_vacs). Our results show that oxygen vacancies induce charge rearrangements, which enhances charge transfer between active sites and adatoms. Furthermore, the incorporation of oxygen vacancies reduces the work function of the system, which makes charge transfer from the inner to the surface more easily; thus, the charges possess stronger redox capacity. As a result, the O_vac reduces both the hydrogen adsorption-free energy (ΔG_H*) for the HER and the overpotential for the OER, facilitating the PEC activity of overall water splitting. The findings provide not only a method to develop bifunctional PEC catalysts based on BiVO₄ but also insight into the mechanism of enhanced catalytic performance.

As a member of the two-dimensional transition metal trihalide (MX3) family, the MnI3 monolayer has recently garnered significant attention due to its unique intrinsic ferromagnetic half-metallic properties and high Curie temperature. However, its inherent in-plane magnetization preference limits its potential applications in spintronics. To address this issue, in this work, we investigate the effects of 3d transition metal V and Cr doping on the electronic structure and magnetic properties of the MnI3 monolayer. The results show that the doped systems exhibit excellent structural stability and out-of-plane ferromagnetic semiconductor properties. In the VMn2I6 and CrMn2I6 monolayer, the adsorption energy can reach −8.421 and −5.796 eV/atom, respectively, and the large magnetic anisotropy energies flip their easy magnetization axis along the z-direction successfully. Moreover, the semiconductor bandgaps can increase to 2.51 and 1.26 eV relative to half-metal MnI3 monolayer. Bader charge analysis reveals that V and Cr doping enhance charge transfer in the MnI3 monolayer and increase the magnetic moment of Mn ions to approximately 4.6 μB. The interstitial doping significantly changes the exchange interactions path between magnetic atoms, leading to a noticeable reduction in the Curie temperature. This work provides an effective approach and theoretical support for regulating the electronic properties and easy magnetization axis orientation in MnI3 two-dimensional materials.

Based on first-principles calculations, this paper presents a study on the stability, electronic structure, ferromagnetic, ferroelectric, and optical properties of Cr2SOCl2 monolayer. The calculations reveal that the Cr2SOCl2 monolayer is a typical magnetoelectric and bipolar magnetic semiconductor with a direct bandgap of 1.25 eV, where the ferromagnetic and ferroelectric ordering can coexist simultaneously below 76 K. The electronegativity difference between S and O atoms leads to a redistribution of charge, which drives the ferroelectric polarization of the Cr2SOCl2 monolayer. The application of uniaxial strain allows for the control of bandgap, light absorption, and carrier mobility in Cr2SOCl2 monolayer. Specifically, when a tensile strain is applied along the y direction, the monolayer undergoes a transition from the bipolar magnetic semiconductor to ferromagnetic half-semiconductor phase. At 12% strain, the absorptivity of Cr2SOCl2 monolayer can reach the maximum (∼8%) within the visible light range; moreover, the mobility of both electrons and holes is large in the x direction, but their difference is small, almost on the same order of magnitude. Based on these findings, we propose that Cr2SOCl2 monolayer under this strain could be a promising ferroelectric photovoltaic material for the absorption layer in solar cells.

Two-dimensional (2D) magnetic materials possess a significant potential in non-volatile information storage and logic devices. MnSiTe3 has been an outstanding candidate for permanent magnet due to its remarkable Curie temperature and large coercivity. However, the physical mechanisms on regulation of the important magnetic properties such as magnetic anisotropy and the exceptionally high Curie temperature in MnSiTe3 are still rarely studied. In this work, we investigated the electronic structure and magnetic properties of MnSiTe3 using different forms of strongly correlated electron functionals. The results indicate that the strongly constrained and appropriately normed (SCAN) functional can effectively capture the strong electron correlations presented in this system. Notably, the magnetic anisotropy energy can be greatly enhanced with a large value of 35.64 meV/unit by using SCAN functional, which is consistent with its exceptionally high Curie temperature. Furthermore, we studied the effect of hydrostatic pressure on the magnetic properties of MnSiTe3. Our calculations reveal that the ferromagnetism of MnSiTe3 initially increases and then decreases by applying a small pressure. We predict that the magnetism may vanish under a critical pressure around 40 GPa with the emergence of lattice instability. These findings reveal the magnetic characteristics of MnSiTe3 and highlight its potential for future applications in magnetic devices.