Chemistry of two-dimensional pnictogens: emerging post-graphene materials for advanced applications

Interplay between the oxidation process and cytotoxic effects of antimonene nanomaterials

Pnictogen nanomaterials have recently attracted researchers' attention owing to their promising properties in the field of electronic, energy storage, and nanomedicine applications. Moreover, especially in the case of heavy pnictogens, their chemistry allows for nanomaterial synthesis using both top-down and bottom-up approaches, yielding materials with remarkable differences in terms of morphology, size, yield, and properties. In this study, we carried out a comprehensive structural and spectroscopic characterization of antimony-based nanomaterials (Sb-nanomaterials) obtained by applying different production methodologies (bottom-up and top-down routes) and investigating the influence of the synthesis on their oxidation state and stability in a biological environment. Indeed, in situ XANES/EXAFS studies of Sb-nanomaterials incubated in cell culture media were carried out, unveiling a different oxidation behavior. Furthermore, we investigated the cytotoxic effects of Sb-nanomaterials on six different cell lines: two non-cancerous (FSK and HEK293) and four cancerous (HeLa, SKBR3, THP-1, and A549). The results reveal that hexagonal antimonene (Sb-H) synthesized using a colloidal approach oxidizes the most and faster in cell culture media compared to liquid phase exfoliated (LPE) antimonene, suffering acute degradation and anticipating well-differentiated toxicity from its peers. In addition, the study highlights the importance of the synthetic route for the Sb-nanomaterials as it was observed to influence the chemical evolution of Sb-H into toxic Sb oxide species, playing a critical role in its ability to rapidly eliminate tumor cells. These findings provide insights into the mechanisms underlying the dark cytotoxicity of Sb-H and other related Sb-nanomaterials, underlining the importance of developing therapies based on controlled and on-demand nanomaterial oxidation.

Thermal Transport in Pentagonal CX2 (X = N, P, As, and Sb)

Two-dimensional (2D) materials with a pentagonal structure have many unique physical properties and great potential for applications in electrical, thermal, and optical fields. In this paper, the intrinsic thermal transport properties of 2D pentagonal CX2 (X = N, P, As, and Sb) are comparatively investigated. The results show that penta-CN2 has a high thermal conductivity (302.7 W/mK), while penta-CP2, penta-CAs2, and penta-CSb2 have relatively low thermal conductivities of 60.0, 36.9, and 11.8 W/mK, respectively. The main reason for the high thermal conductivity of penta-CN2 is that the small atomic mass of the N atom is comparable to that of the C atom, resulting in a preferable pentagonal structure with stronger bonds and thus a higher phonon group velocity. The reduction in the thermal conductivity of the other three materials is mainly due to the gradually increased atomic mass from P to Sb, which reduces the phonon group velocity. In addition, the large atomic mass difference does not result in a huge enhancement of the anharmonicity or weakening of the phonon relaxation time. The present work is expected to deepen the understanding of the thermal transport of main group V 2D pentagonal carbons and pave the way for their future applications, also, providing ideas for finding potential thermal management materials.

Recent advanced strategies for bimetallenes toward electrocatalytic energy conversion reactions

Designing low-dimensional nanomaterials is vital to address the energy and environmental crisis by means of electrocatalytic conversion reactions. Bimetallenes, as an emerging class of 2D materials, present promise for electrocatalytic conversion reactions. By leveraging atomically thin layers, bimetallenes present unsaturated surface coordination, high specific surface area and high conductivity, which are all indispensable features for heterogeneous electrochemical reactions. However, the intrinsic activity and stability of bimetallenes needs to be improved further for bimetallene electrocatalysts, due to the higher demands of practical applications. Recently, many strategies have been developed to optimize the chemical or electronic structure to accommodate transfer of reactants, adsorption or desorption of intermediates, and dissociation of products. Considering that most such work focuses on adjusting the structure, this review offers in-depth insight into recent representative strategies for optimizing bimetallene electrocatalysts, mainly including alloying, strain effects, ligand effects, defects and heteroatom doping. Moreover, by summarizing the performance of bimetallenes optimized using various strategies, we provide a means to understand structure-property relationships. In addition, future prospects and challenges are discussed for further development of bimetallene electrocatalysts.

Red phosphorus encapsulated in 3D N-doped porous carbon nanofibers: an enhanced sodium-ion battery anode material

We report a sodium-ion battery anode design using red phosphorus encapsulated in nitrogen-doped porous carbon nanofibers that mitigates volume expansion and poor conductivity issues, enhancing battery performance. Density functional theory calculations suggest nitrogen doping promotes robust phosphorus interactions, and finite element analysis indicates the design controls volume expansion.