Designing new materials with novel topological properties and reduced dimensionality is always desirable for material innovation. Here we report the design of a two-dimensional material, namely Be₅C₂ monolayer on the basis of density functional theory computations. In Be₅C₂ monolayer, each carbon atom binds with five beryllium atoms in almost the same plane, forming a quasi-planar pentacoordinate carbon moiety. Be₅C₂ monolayer appears to have good stability as revealed by its moderate cohesive energy, positive phonon modes and high melting point. It is the lowest-energy structure with the Be₅C₂ stoichiometry in two-dimensional space and therefore holds some promise to be realized experimentally. Be₅C₂ monolayer is a gapless semiconductor with a Dirac-like point in the band structure and also has an unusual negative Poisson’s ratio. If synthesized, Be₅C₂ monolayer may find applications in electronics and mechanics.

Low-dimensional semiconducting materials with moderate band gaps as well as high carrier mobilities are highly sought for future application in microelectronics. By means of hybrid density functional theory computations, we predicted that a novel two-dimensional (2D) IV–VI material, namely germanium monosulfide (GeS) monolayer, is a rather desirable candidate. According to our computations, GeS monolayer is semiconducting with an indirect band gap of 2.34 eV, which can be effectively tuned by employing an external strain. Remarkably, the GeS monolayer has an electron mobility of 3680 cm² V⁻¹ s⁻¹, which is much higher than that of MoS₂ monolayer. Our computations also revealed that GeS monolayer is a stable structure and can be obtained by exfoliation or mechanical cleavage techniques. These findings render GeS monolayer a promising 2D material for applications in future microelectronics, and call for more research attention on 2D IV–VI materials.

A covalently coupled hybrid of graphitic carbon nitride (g-C₃N₄) and reduced graphene oxide (rGO) is fabricated via an in situ chemical synthesis approach and used to load Pd nanoparticles. It is found that the Pd nanoparticles with an average diameter of 3.83 nm are evenly deposited on the g-C₃N₄–rGO surface. Compared with the Pd–rGO and commercial Pd–AC (Pd–activated carbon) catalysts, the ternary Pd–g-C₃N₄–rGO nanocomposite exhibits excellent electrocatalytic properties toward both formic acid and methanol electrooxidation, such as extremely large electrochemically active surface area (ECSA) values, significantly high forward peak current densities and reliable long-term stability. The enhanced electrochemical activity can be attributed to the specific characteristics of the unique nanostructure of Pd–g-C₃N₄–rGO and the concerted effects of the individual components, including the superior conductivity of rGO, the high specific surface area of the mesoporous structure, the good structural stability due to the covalent interactions between g-C₃N₄ and rGO, and the highly dispersed Pd nanoparticles as a result of the effect of planar groups of g-C₃N₄.

Intrinsic van der Waals materials layered magnets have attracted much attention, especially the air-stable semiconductor CrSBr. Herein, we carry out a comprehensive investigation of both bulk and monolayer CrSBr using the first-principles linear-response method. Through the calculation of the magnetic exchange interactions, it is confirmed that the ground state of bulk CrSBr is A-type antiferromagnetic, while there are five sizable large intralayer exchange interactions with small magnetic frustration, which results in a relatively high magnetic transition temperature of both bulk and monolayer CrSBr. Moreover, the significant electron doping effect and strain effect are demonstrated, with further increased Curie temperature for monolayer CrSBr, as well as an antiferromagnetic to ferromagnetic phase transition for bulk CrSBr. We also calculate the magnon spectra using linear spin-wave theory. These features of CrSBr can be helpful to clarify the microscopic magnetic mechanism and promote the application in spintronics.

The electronic properties of hydrofluorinated graphene nanosheets can be efficiently modified by interlayer C–H⋯F–C hydrogen bonding.