Presenter 1: Marlies Hankel (Research Fellow & RCC/QCIF Analyst, Bernhardt group, AIBN)

Title: Two-dimensional carbon nitride materials as gas sensors and lithium ion battery anode materials

Abstract: Two-dimensional (2D) nanomaterials have attracted interest in recent times due to their promise in various applications. Graphene and other 2D materials have been extensively studied over recent decades as energy storage materials. One of the industry applications is as the anode of lithium (Li) ion batteries. A high surface to area ratio also makes 2D materials attractive for gas sensing. Here we will present our recent work on carbon nitride materials for Li ion battery anode materials and sensing. We have shown that experimentally synthesized carbon nitride 2D materials such as g-C3N4, g-CN (g-C3N3) and hC2N form strong ionic bonds with Li and have a high Li storage capacity. They also induce a large charge transfer from the Li to the material. In a recent study we also showed that these 2D materials are excellent for sensing of NH3 and H2S due to a large change in their band gap, while the electronic structure remains unchanged in the presence of CH4, CO2 and SO2 for example.


Presenter 2: Chunmei Zhang (PhD student, Du group, QUT)

Title: Computational Discovery and Design of Novel Dirac Materials

Abstract: Dirac-like band spectrum was first discovered in graphene, and the existence of Dirac points around the Fermi level endows graphene with many extraordinary properties including high electron mobility, conductivity, quantum Hall effects, and so on. Such unusual band dispersion near the Fermi level enabling the electrons to behave like relativistic particles can be extended to other materials from three dimensional (3D) to one dimensional (1D) materials. And the Dirac points in Dirac materials are protected by the interplay of symmetry, which vary from material to material. In our work, through the combination of density functional theory (DFT) calculations and Tight-binding (TB) models, we designed and discovered a series of Dirac materials:

1. A two dimensional WB4 monolayer, which exhibits double Dirac cone, are developed to provide a sizable band gap while maintaining the higher charge mobili­ty with a Fermi velocity 1.099×106 m/s.

2. Through extensively studied the monolayer MB2 crystal with M elements ranging from group IIA to IVB covering thirty-two candidates. Eight stable monolayers MB2 (M=Be, Mg, Fe, Ti, Hf, V, Nb, Ta) are extracted, and they exhibit Dirac-like band structure with ultrahigh Fermi velocity. Dramatically, among them, groups IVA-VA transition-metal diboride MB2 (M=Ti, Hf, V, Nb, Ta) harbour in-plane negative Poisson’s ratio arising mainly from the orbital hybridization between M d orbitals and Boron p orbitals.

3. Dirac cone like bands emerges at the 1D zigzag interface of ZnO/MoS2 lateral heterostructure (LHS), creating a highly mobile 1D transport channel with a high Fermi velocity of 4.5 x 105 m/s.  The metallic state at 1D hetero-interface is attributed to the polar discontinuity that introduces excess charge carriers.

4. Rings of Dirac nodes formed by multiple Dirac points and a distorted Dirac cone are found coexist in the LaCuO3 compound.


Date: Thursday, 16 August 2018

Time: 9.30 – 10.30am

Venue: AIBN Seminar Room, Level 1 (Building 75)


AIBN Seminar Room, Level 1 (Building 75)