High-Resolution Three-Dimensional Sculpting of Two-Dimensional Graphene Oxide by E-Beam Direct Write

A novel two-dimensional superconducting Ti layer: density functional theory and electron-beam irradiation

Since the discovery of graphene in an atomic thin layer format, many investigations have been conducted to search for two-dimensional (2D) layered materials, in which 3d-transition metals offer much new physics and great freedom of tunability. In this work, through electron-beam irradiation, we enable the manufacture of a new 2D Ti nanosheet from a suspension of Ti_0.91O₂ nanosheets. In state-of-the-art density functional theory (DFT), both empirical and linear response theory predicted that Hubbard U_eff values would be imposed, resulting in unstable phonon dispersion curves. In the end, the newly found Ti monolayer is confirmed to be a non-magnetic superconductor, with a medium level of electron-phonon coupling. The newly established Ti layer is quite robust under strain, and the evolution of local Dirac points in electronic bands is also analyzed in terms of linearity and energetic shift near the Fermi energy. As suggested by the Fermi surface, this metal monolayer experiences an electronic topological transition under strain. Our findings will encourage many more explorations of pure d metal-based isotopic monolayers with diverse structures and open a new playground for 2D superconductors and ultra-thin sensoring components.

Vacancy designed 2D materials for electrodes in energy storage devices

Vacancies are ubiquitous in nature, usually playing an important role in determining how a material behaves, both physically and chemically. As a consequence, researchers have introduced oxygen, sulphur and other vacancies into bi-dimensional (2D) materials, with the aim of achieving high performance electrodes for electrochemical energy storage. In this article, we focused on the recent advances in vacancy engineering of 2D materials for energy storage applications (supercapacitors and secondary batteries). Vacancy defects can effectively modify the electronic characteristics of 2D materials, enhancing the charge-transfer processes/reactions. These atomic-scale defects can also serve as extra host sites for inserted protons or small cations, allowing easier ion diffusion during their operation as electrodes in supercapacitors and secondary batteries. From the viewpoint of materials science, this article summarises recent developments in the exploitation of vacancies (which are surface defects, for these materials), including various defect creation approaches and cutting-edge techniques for detection of vacancies. The crucial role of defects for improvement in the energy storage performance of 2D electrode materials in electrochemical devices has also been highlighted.

Black Phosphorus Nanosheet Encapsulated by Zeolitic Imidazole Framework-8 for Tumor Multimodal Treatments

Black phosphorus (BP) nanosheet is easily oxidized by oxygen and water under ambient environment, thus, reliable BP passivation techniques for biomedical applications is urgently needed. A simple and applicable passivation strategy for biomedical applications was established by encapsulating BP nanosheet into zeolitic imidazole framework-8 (ZIF-8). The resulted BP nanosheet in ZIF-8 (BP@ZIF-8) shows not only satisfied chemical stability in both water and phosphate buffered saline (PBS), but also excellent biocompatibility. Notably, BP nanosheet endows the prepared BP@ZIF-8 with prominent photothermal conversion efficiency (31.90%). Besides passivation BP, ZIF-8 provides the BP@ZIF-8 with high drug loading amount (1353.3 mg g^-1). Moreover, the loaded drug can be controlled release by pH stimuli. Both in vitro and in vivo researches verified the resulted BP@ZIF-8 an ideal candidate for tumor multimodal treatments.