Atomic-layered hexagonal boron nitride (hBN) is expected to be the best two-dimensional (2D) anti-oxidation layer on metals for its incomparable impermeability, insulativity, and stability, as well as the progressive bottom-up growth techniques to ensure fast coating on metal surface in large area. However, its real anti-oxidation ability in practice is found to be unsatisfactory and nonuniform, and the main obstacle to achieving ideal anti-oxidation performance lies in unclear anti-oxidation behavior at special interface between 2D hBN and three-dimensional (3D) metals. Herein, system of monolayer hBN grown on copper (Cu) foils with various lattice orientations was grown to investigate the anti-oxidation behavior of different interlayer configurations. By using structural characterizations together with analysis of topography, we surprisingly found that stronger interlayer coupling led to worse anti-oxidation performance owing to fast diffusion of O₂ through higher hBN corrugations generated at the commensurate hBN/Cu(111) configuration. In view of this, we developed the approach of cyclic reannealing that can effectively flatten corrugations and steps, and therefore improve the anti-oxidation performance to a great extent. This work provides a more in-depth understanding of anti-oxidation behavior of 2D materials grown on 3D metals, and a practical method to pave the way for its large-scale applications in future.

Solid electrolyte based-resistive memories have been considered to be a potential candidate for future information technology with applications in non-volatile memory, logic circuits and neuromorphic computing. A conductive filament model has been generally accepted to be the underlying mechanism for the resistive switching. However, the growth dynamics of such conductive filaments is still not fully understood. Here, we explore the controllability of filament growth by correlating observations of the filament growth with the electric field distribution and several other factors. The filament growth behavior has been recorded using in situ transmission electron microscopy. By studying the real-time recorded filament growth behavior and morphologies, we have been able to simulate the electric field distribution in accordance with our observations. Other factors have also been shown to affect the filament growth, such as Joule heating and electrolyte infrastructure. This work provides insight into the controllable growth of conductive filaments and will help guide research into further functionalities of nanoionic resistive memories.

Single-walled carbon nanotubes (SWNTs) are expected to be an ideal candidate for making highly efficient strain sensing devices owing to their unique mechanical, electronic, and electromechanical properties. Here we present the use of fluorphlogopite mica (F-mica) as a flexible, high-temperature-bearing and mechanically robust substrate for the direct growth of horizontally aligned ultra-long SWNT arrays by chemical vapor deposition (CVD), which in turn enables the straightforward, facile, and cost-effective fabrication of macro-scale SWNT-array-based strain sensors. Strain sensing tests of the SWNT-array devices demonstrated fairly good strain sensitivity with high ON-state current density.