Main Research Interests:

● Experiment and molecular simulation for characterization of porous nanomaterials in chemical engineering

Novel porous nanomaterials have many potential applications, such as adsorption separation, gas storage, catalysis and nanoreactors. In this field, we investigate adsorption properties of various porous nanomaterials, including activated meso carbon micro beads, and fibres, single-walled carbon nanotube (SWNT), MCM-41, ZSM zeolite, pillared clays etc. Emphasis is placed on experimental characterizations and molecular modeling of these materials. Molecular simulation is used to explore microstructure and phase behavior of fluids in these materials, in order to get insight into the effect of geometrical morphology of these materials on adsorption from the micorscopic point of view. Molecular dynamics is also used to study diffusion and transport of fluids in a nanochannel.

● Experiment and molecular simulation for structure and catalytic performances of bimetallic nanoclusters on solid substrates

As the building blocks of nanoscale materials, bimetallic clusters are more promising for catalytic, optical, and magnetic applications than their monometallic ones. Besides their peculiar properties devoted to industrial applications, bimetallic clusters are interesting, since their properties depend not only on size but also on composition and atomic ordering. Supported metal clusters are relatively new model catalysts, which have attracted much attention. A detailed understanding of their structural and thermal properties is of great importance for the controlled preparation and design of these clusters. In this field, we focus on the free and supported transition bimetallic clusters, such as Pd-Pt, Ag-Au, Ag-Cu, Pd/MgO, Pd-Pt/MgO, Au/MCM-41, Pd/SWNT, Pt-Ru/MCM-41 et al., by using experimental and theoretical methods. In experiment, we first prepare the bimetallic clusters based on chemical processes, then observe them by TEM, UV/VIS, NMR et al., and finally we test their catalytic activity and selectivity by chemical reactions. In molecular simulation, we first develope a molecular simulation platform "A Monte Carlo Method to Study Bimetallic Clusters", then study the structural and thermal properties of free bimetallic clusters, and finally observe thermal evolution of supported elemental metal and bimetallic clusters, such as MgO(100)-supported Pd-Pt clusters and Pt-filled carbon nanotubes.

● Quantum mechanics/molecular mechanics (QM/MM) method for the development of the force fields of inoic liquids

Room temperature ionic liquids (RTILs) are organic salts with a melting point as low as room temperature. Due to the Coulombic interactions between cations and anions, RTILs have many unique properties, such as negligible vapor pressure, adjustable solvation behavior, thermal stability, leading to their broad applications in various fields.Computer simulations have been playing an important role in molecular design, which is especially useful for RTILs because of their tremendous diversity. Nevertheless, success of molecular simulation mainly depends on the quality of the inter- and intra-molecular potential functions, i.e. the force fields. We have developed a refined all-atom force field for imidazolium RTILs based AMBER with good accuracy. Without reducing the accuracy, a united-atom force field is also proposed to decrease the computational intensity. The properties of the pure RTILs and their mixtures with coventional solvents can be predicted by the force field. The studies of the behavior of liquids-gas, liquid-solid and liquid-liquid interfaces with RTILs are also carried out.

● Molecular simulation and density functional theory for microstructure and self-assembly of charged polymers with complex architecture

Architectures of polymers and the thermodynamic properties for blocks often determine the microstructure and morphology of the self-assmbled polymers in nanochannels. The density functional theory (DFT) is used to investigate microstructure and self-assembly of polymers with complex architectures. In the DFT, single chain Monte Carlo simulation is adopted to evaluate the ideal-gas contribution of the Helmholtz energy and density functional for the excess part. Besides, molecular simulation is used to explore microscopic properties of charged star-shaped and brached polymers. The emphasis is placed on the effect of the added salt on the morphology and electircal properties of the charged polymers.

● Adsorption and self-assembly of surfactant molecules

Surfactant molecules usually consist of two distinct groups that differ significantly in their solubility. Consequently, surfactant molecules aggregate spontaneously to form a variety of mesostructures in mixtures with water or oil. The presence of solid surfaces would not only result in adsorption of surfactants, but also induce morphology transitions. Understanding of adsorption and self-assembly of surfactants on solid surfaces is vital for their role in industrial processes. Our main interests are to understand the equilibrium and kinetic properties of surfactant systems in the presence of solid surfaces, by using a number of computer simulation techniques.

● Adsorption, diffusion and transport phenomena in nanopores and membrane materials by MC, MD and Non-equilibrium MD (NEMD)

Nanopore size in a membrane material often dominates the diffusion and transport of fluids confined in the membrane, especaily for the metal-decorated membrane. Furthermore, the adsorption properties of the membrane also affect diffusion behavior of the fluids. Monte Carlo simulation and Non-equilibrium MD are used to investigate adsorption, diffusion and transport phenomena of fluids in the membrane. The object is to find the relationship between transport phenomena of fluids and the parameters of nanopores.