Youguo Yan

Theoretical evaluation of inhibition performance of purine corrosion inhibitors

Inhibition mechanism of three purine compounds, adenine (A), 2-amino-6-thiol-9H-purine (B) and 2,6-dithiol-9H-purine (C), was investigated by quantum chemical calculation and molecular dynamic simulation. The molecular reactivity was studied by quantum chemical calculation, and the distribution of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the energy gap between HOMO and LUMO and the Fukui index were proposed to describe the active sites of molecules, and the inferred inhibition efficiency followed the order of A < B < C. Furthermore, the adsorption behaviour of these three purine molecules on a metal surface was investigated via molecular dynamics simulation. The analysis of adsorption configuration indicated that these three purine molecules adsorbed parallely onto the metal surface, and the inferred inhibition efficiency from interaction energy also followed the order of A < B < C. These inferred inhibition efficiency from theoretical calculation was in good accordance with experimental results. This accordance indicated that our proposed theoretical method might be a feasible approach to assess the inhibition performance of inhibitors. Moreover, our research was helpful to filter the aimed inhibitor and design of the new inhibitor.

Synthesis of ZnO nanotowers controlled by a reagent's vapour pressure

In this work, ZnO nanotowers with layer-by-layer structure were prepared using Zn as a source at 700xa0°C via the chemical vapour deposition method. In the growth process, the Zn vapour pressure was considered as the crucial factor determining the growth behaviour of reagent species, and a competitive model between axial and lateral growth controlled by Zn vapour pressure was proposed to explain the formation of the tower-shaped structure. Several other experiments were conducted to analyse the growth behaviour under different Zn vapour pressures. Experimental results indicated that decreasing Zn vapour pressure was responsible for the formation of the layer-by-layer structure. A high Zn vapour pressure would induce the formation of a nanotower with large diameter and thin layer, and a low Zn vapour pressure would result in the formation of a nanotower with small diameter and thick layer. These experimental results further confirmed the competitive growth model. Our growth analyses were helpful in understanding the microcosmic growth behaviour of reagent species, which contributed to realizing controlled growth of complex nanostructures in the vapour route. Furthermore, these obtained nanotowers might have potential applications as functional blocks in future nanodevices.