Visualization of Transition Metal Decoration on h-BN Surface

Abstract

Functional h-BN (hexagonal boron nitride) has been prepared via the incorporation of transition metal (TM) impurities like nanoparticles and single atoms. Herein, scanning transmission electron microscopy (STEM) combined with density functional theory (DFT) was employed to study Ta-, Co-, Ni-, and Ir-decorated h-BN monolayers to provide an overview of their preferential site occupancies and morphological evolutions on h-BN. Ta, Ni, Ir, and Co single atoms are all positioned on the nitrogen of h-BN; however DFT predicts the occupancy site can vary with their spin state. In terms of microstructural evolution, Co, Ni, and Ir atoms form 3D nanoclusters while Ta atoms are well dispersed and thus the single Ta atom can be decorated on h-BN. This study highlights on TM/h-BN interaction dynamics and presents an avenue for designing nanostructures for electrocatalytic application.

Single-Atom-Kernelled Nanocluster Catalyst

“…It is well-known that the catalysis is closely related to the catalyst surface and the bulk atoms of metal catalysts are usually less important than the surface metal atoms during the reaction. − Thus, the small size of metal catalysts is beneficial to the improvement of metal utilization efficiency, which is particularly important for those cases requiring expensive metal (e.g., Au, Pt) components. − In this context, catalysts with a high ratio of surface metal atoms are in demand, among which mononuclei-metal compounds especially single-atom catalysts with a theoretical metal utilization rate of 100% have received increasing attention in recent years. − However, the shortcoming of such catalysts is that they can not provide the sites with multiple metal atoms or metal ensemble required by some catalytic reactions, which limits their applications. On the contrary, classic metal nanoparticles (nanocrystals) can offer the sites with multiple metal atoms or metal ensemble, but they have low metal utilization efficiency due to the existence of abundant bulk atoms compared with single-atom catalysts .…”

Atomistic Probing of Defect-Engineered 2H-MoTe2 Monolayers

“…Atomically thin 2D materials are prone to structural degradation, which often result in a compromised optoelectronic property; − therefore, a continuous search for nondestructive and efficient defect-engineering technologies is still ongoing. Fifth-order spherical aberration-corrected scanning transmission electron microscopy (5 th -order C s -corrected STEM) has been an indispensable tool to enable the visualization and study of defect dynamics with high-speed subpicometer resolution. , However, the large amount of data generated during atomic structural imaging and the complexity of the structural defects make it tortuous, time-consuming, and nearly impossible to identify defect species with a high precision. , Therefore, there is a compelling need to combine automated defect identification and classification algorithm, e.g. , deep learning, to study structure–property interdependence in defect-engineered 2D materials. , …”

“…Fifth-order spherical aberration-corrected scanning transmission electron microscopy (5 th -order C s -corrected STEM) has been an indispensable tool to enable the visualization and study of defect dynamics with high-speed subpicometer resolution. 17 , 18 However, the large amount of data generated during atomic structural imaging and the complexity of the structural defects make it tortuous, time-consuming, and nearly impossible to identify defect species with a high precision. 19 , 20 Therefore, there is a compelling need to combine automated defect identification and classification algorithm, e.g.…”

Geometrical and magnetic properties of small titanium and chromium clusters on monolayer hexagonal boron nitride

“…31 One of these insulating substrates that is under experimental considerations is hexagonal boron nitride (h-BN), an atomic layered material with a bandgap of 5.1 eV that can be engineered through TM atom decoration. 32 The lattice of h-BN is very attractive for creating novel spin structures, and theoretical predictions on the spin structures of small TM clusters on the h-BN layer are strongly desired for performing STM experiments.…”