Electronic Topological Transition of 2D Boron by the Ion Exchange Reaction

Abstract

We systematically investigated electronic evolutions of nonsymmorphic borophene with chemical environments that were realized by the ion exchange method. Electronic structures can be characterized by the topological invariant. Spectroscopic experiments and DFT calculations unveiled that a sheet of hydrogenated borophene (borophane) is the Dirac nodal loop semimetal ( ), while a layered crystal of YCrB4 is an insulator ( ). The results demonstrate the electronic topological transition by replacement of the counter atoms on the nonsymmorphic borophene layer.

Highly Dispersed Ni Nanoclusters Spontaneously Formed on Hydrogen Boride Sheets

“…Furthermore, theoretical studies have revealed their intriguing electronic [ 9 ], optical, and thermal properties [ 10 , 11 ], as well as their possible applications in hydrogen release devices [ 12 , 13 ], reversible hydrogen storage [ 14 ], current limiters [ 15 ], photodetectors, individual amino acid sensors [ 16 ], rechargeable Li/Na ion battery electrodes [ 17 , 18 ], and anodes for rechargeable potassium-ion batteries, with high capacities, low voltages, and high rate performance [ 19 ]. Furthermore, the formation of HB sheets has paved the way for the conceptual development of new types of HB materials [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Prediction of a Cyclic Hydrogenated Boron Molecule as a Promising Building Block for Borophane

“…The molecule 2:4:6:8:-2H-1,5:1,5-μH-B 8 H 10 has a five-membered boron ring on each of the two sides of the 3c-2e bond, as shown in Figure 1 b,c. The topological borophane layer (α-HB sheet) reported recently also has such a pair of five-membered rings in its sheet structure, as shown in Figure 4 a,b [ 12 , 13 ]. Among the different arrangements, the pair unit is the tiled β-HB sheet ( Figure 4 c,d).…”

“…It is noteworthy that its kinetic stability was supported by the positive vibrational energy of the phonon modes. This material was successfully synthesized through an ion-exchange reaction [ 12 , 13 ]. The α-HB sheet is a semimetal, with electronic states of the Dirac nodal loop (DNL) at the Fermi level.…”

“…Theoretical and experimental searches for 2D boron have been extended to seeking low-dimensional materials composed of boron and other elements [ 7 ]. An example is the recent synthesis of sheets of hydrogen boride (HB) or borophane [ 11 , 12 , 13 ], which show intriguing functions such as hydrogen storage [ 14 ]. Boron and hydrogen atoms create a three-center two-electron (3c-2e) bond with unique chemical characteristics that allow us to design new 2D HB structures [ 15 , 16 , 17 ].…”

“…The molecule has a 3c-2e bond at the center and two five-membered rings on the sides. The nomenclature of the molecule is based on references [ 19 , 20 ]; its atomic structure can be regarded as a building block of a topological borophane layer, discovered recently [ 12 , 13 , 15 , 17 ]. This research shows intriguing relationships between the planar molecules and atomic sheets of the hydrogenated boron compound.…”