Phosphorene is a new two-dimensional material that has recently attracted much attention owing to its fascinating electrical, optical, thermal and chemical properties. Here, we report on high-quality exfoliation of black phosphorus nanosheets, with controllable size produced in large quantities by liquid-phase exfoliation using N -methyl-2-pyrrolidone (NMP) as a solvent under ambient conditions. The as-synthesized few layers show a great potential for solar energy conversion based on the optical results shown in this work.

The electronic and electrochemical investigations of a Na-adsorbed BC₂N/Blue phosphorene van der Waals heterostructure show that it may operate as a promising anode material for sodium-ion batteries.

Combining multiple degrees of freedom in strongly correlated materials such as transition-metal oxides would lead to fascinating magnetic and magnetocaloric features. Herein, the strain effects are used to markedly tailor the magnetic and magnetocaloric properties of PrVO₃ thin films. The selection of an appropriate thickness and substrate enables us to dramatically decrease the coercive magnetic field from 2.4 T previously observed in sintered PVO₃ bulk to 0.05 T for compressive thin films making from the PrVO₃ compound a nearly soft magnet. This is associated with a marked enhancement of the magnetic moment and the magnetocaloric effect that reaches unusual maximum values of roughly 4.86 μ_B and 56.8 J/kg K with the magnetic field change of 6 T applied in the sample plane in the cryogenic temperature range (3 K), respectively. This work strongly suggests that taking advantage of different degrees of freedom and the exploitation of multiple instabilities in a nanoscale regime is a promising strategy for unveiling unexpected phases accompanied by a large magnetocaloric effect in oxides.

MnFe₂O₄ ferrite nanoparticle was synthesized via the sol–gel method, and structural, morphology and magnetic characteristics were investigated. X-ray diffraction analysis showed that the synthesized sample was in a single phase with a spinel-ferrite-like structure (space group Fd-3m). The scanning electron microscopy displayed homogenous spherical grains with an agglomeration of the particles. The chemical composition determined by energy-dispersive spectroscopy shows the absence of any impurities. To understand the role of magnetic interaction in MnFe₂O₄ spinel ferrites, the structural and magnetic properties of MnFe₂O₄ have been explored theoretically. Based on the first-principles methods via density functional theory and Monte Carlo simulations, the magnetic hysteresis cycle has been plotted. Using the generalized gradient and GGA-PBE approximation in the full-potential linearized augmented plane wave (FP-LAPW) method, the exchange coupling interactions between magnetic elements and local magnetic moment were evaluated. Furthermore, the theoretical magnetic properties of MnFe₂O₄ were found to match the experimental ones. They both revealed that MnFe₂O₄ is a soft ferromagnetic material. The theoretical curve of magnetization versus temperature indicates that the transition occurred at T_c = 580.0 K. This was also in good agreement with the experimental Curie temperature.

Phosphorene, a new two-dimensional material, was investigated theoretically as a promising photocatalyst material. The structural and electronic properties of phosphorene were studied using hybrid functional based HSE approximation. The effect of the adsorbed molecules on the phosphorene surface was studied for various chemical elements, such as water molecule (H₂O), hydronium ion (H₃O⁺), hydrogen atom and ion (H/H⁺), hydroxide molecule (OH), and hydroxide ion (OH⁻). The potential application of phosphorene as a photocatalyst in vacuum was proved under different pH values. A pH of 8 was found to be the suitable value for clean phosphorene in which the flat band position was corrected for the oxidizing and reducing potentials of phosphorene, but the presence of OH⁻ ions in a basic solution damaged the surface structure and limited the use of phosphorene in photocatalysis caused by the high content (0.25 ML and 0.5 ML) of the adsorbed OH⁻ on the phosphorene surface. The obtained results matched the required parameters of a photocatalyst for water splitting using clean phosphorene surface in neutral solution (pH = 7).

We report on theoretical investigations of a methylammonium lead halide perovskite system loaded with iron oxide and aluminum zinc oxide ($\mathrm{ZnO}:\mathrm{Al}/{\mathrm{MAPbI}}_3/{\mathrm{Fe}}_2{\mathrm{O}}_3$) as a potential photocatalyst. When excited with visible light, this heterostructure is demonstrated to achieve a high hydrogen production yield via a z-scheme photocatalysis mechanism. The ${\mathrm{Fe}}_2{\mathrm{O}}_3$: ${\mathrm{MAPbI}}_3$ heterojunction plays the role of an electron donor, favoring the hydrogen evolution reaction (HER), and the $\mathrm{ZnO}:\mathrm{Al}$ compound acts as a shield against ions, preventing the surface degradation of ${\mathrm{MAPbI}}_3$ during the reaction, hence improving the charge transfer in the electrolyte. Moreover, our findings indicate that the $\mathrm{ZnO}:\mathrm{Al}/{\mathrm{MAPbI}}_3$ heterostructure effectively enhances electrons/holes separation and reduces their recombination, which drastically improves the photocatalytic activity. Based on our calculations, our heterostructure yields a high hydrogen production rate, estimated to be $265.05 \mathsf{\mu }\mathrm{mol}/\mathrm{g}$ and $362.99 \mathsf{\mu }\mathrm{mol}/\mathrm{g}$, respectively, for a neutral pH and an acidic pH of 5. These theoretical yield values are very promising and provide interesting inputs for the development of stable halide perovskites known for their superlative photocatalytic properties.