Shaolin Zhang

Correlation between lateral size and gas sensing performance of MoSe2 nanosheets

We demonstrate a facile synthetic method to prepare lateral size controlled molybdenum diselenide (MoSe2) nanosheets using liquid phase exfoliated few-layer MoSe2 nanosheets as a starting material. By precisely controlling the centrifugation condition, preparation of MoSe2 nanosheets with a narrow size distribution ranging from several hundred nanometers to several micrometers could be realized. The accurate size control of MoSe2 nanosheets offers us a great opportunity to examine the size dependent sensing properties. The sensing test results demonstrate that the MoSe2 nanosheets provide competitive advantages compared with conventional graphene based sensors. A tradeoff phenomenon on sensing response and recovery as the lateral size of MoSe2 nanosheets varies is observed. First principles calculations reveal that the ratio of edge-surface sites is responsible for this phenomenon. The correlation between the lateral size and gas sensing performance of MoSe2 nanosheets is established.

FIRST-PRINCIPLES STUDY OF Ti-CATALYZED HYDROGEN ADSORPTION ON LiB (001) SURFACE

Ti-doped LiB (001) is a promising material for hydrogen storage. The adsorption of H2 is greatly enhanced by doping Ti into LiB (001), change the electronic structures of the surface Li, B atoms. After H2 is adsorbed on the surface, the Ead of the (H2)n@Ti/LiB (001) system is considered. It is around -0.22 eV/H2 to -0.31 eV/H2, which is close to the target specified by U.S. Department of Energy. The nature of the bonding between Ti and H2 is due to the H 1s, Ti 4s and B 2s orbital hybridization. In addition, Ti 3d orbital is hybridized strongly with B-2p orbital, resulting in more stable Ti/LiB (001) system. These results are verified by the electron density distribution intuitively. It is found that the system can adsorb up to four H2 at ambient temperature and pressure. Therefore, the Ti-doped LiB (001) would be a promising hydrogen storage material. Such optimal molecular hydrogen adsorption system makes H2 adsorption feasible at ambient conditions, which is critical for practical applications.

Preparation and tribological properties of homogeneously dispersed graphene-reinforced aluminium matrix composites

ABSTRACT Aluminium matrix composites reinforced with homogeneously dispersed graphene (Gr/Al) were fabricated by electrostatic self-assembly and powder metallurgy. The microstructure of the composites was observed. The effects of graphene content, applied load and sliding speed on the tribological properties of the composites were also investigated. The results show that graphene is homogeneously dispersed in the aluminium matrix. The coefficient of friction for the composites initially increases and later decreases with increasing graphene content. It is lowest in the 0.3 wt-% Gr/Al composite, which is a decrease of approximately 20% when compared to that of pure aluminium. The coefficient of friction of the composites appears to increase significantly when increasing the applied load. However, it decreases with increases in the sliding speed.

Fe-doped Bi4O5Br2 Visible Light Photocatalyst: A First Principles Investigation

This study employed first principles calculations to investigate Fe-doped Bi4O5Br2 as a potential photocatalyst with high efficiency. Based on formation energy calculation, the Fe atoms prefer to r...