Zhanxi FAN Group
Research
Our group is open to any new ideas that can address the fundamental problems and practical challenges in the fields of materials chemistry, nanoscience, catalysis, and energy conversion. Currently, our research interests mainly focus on the rational design, controlled syntheses, advanced characterizations, formation mechanisms, basic properties and potential applications of novel low-dimensional metal and metal-based nanomaterials. Besides the well-established size, shape and composition control of metal and metal-based nanomaterials, we will try to improve/change their physicochemical properties and boost their performance in various applications via crystal phase control, surface modification, defect engineering, coordination environment modulation, metal-support interaction, electronic structure hybridization, etc. In this way, we aim to decrease the cost of materials processing and increase the atomic utilization efficiency of metals (especially noble metals) towards real applications.
Controlled synthesis of novel metal nanomaterials
Owing to the unique d-band electronic structure and intriguing physicochemical properties, metal nanomaterials have been extensively used in many important applications, such as surface-enhanced Raman scattering, plasmonics, catalysis, energy conversion, sensing, information storage, bioimaging and photothermal therapy. The last two decades have witnessed the great development of metal nanomaterials by manipulating their sizes, shapes, compositions, facets, dimensions and architectures. However, previous studies are almost limited to investigate the thermodynamically stable crystal phases/structures of metal nanomaterials. Very recently, studies have revealed that the crystal phase, which is closely related to the electronic structure of materials, can also significantly affect the properties of metal nanomaterials. Therefore, the crystal phase-controlled synthesis of metal nanomaterials could open up new opportunities. We have developed three synthetic strategies, i.e. one-pot colloidal synthesis, surface modification and template synthesis, for the crystal phase control of metal nanomaterials. By using these approaches, we have pioneered the synthesis of 4H hexagonal Au nanoribbons, discovered a non-classical phase transformation mechanism of close-packed metals/alloys, and achieved the general synthesis of many other metal nanostructures (e.g. Pt, Pd, Ir, Rh, Os, Ru, Cu, PdAg, PtAg and PtPdAg) with the unusual 4H phase. We will continue to explore this newly emerged research area, and try to synthesize novel metal nanomaterials with unusual or unprecedented crystal phases and investigate their properties and applications.
Designed preparation of functional metal-based heteronanostructures
Given the synergistic effects between different materials, preparation of heteronanostructures with the integration of two or more materials represents one of the most effective ways to overcome the shortcomings of individual components. In the preparation of metal-based heteronanostructures, it is of paramount importance to have good interface, uniform distribution and physicochemical interaction between metal and the other types of materials. To meet these requirements, synthetic methods like chemical conversion, site-selective overgrowth and in-situ deposition are usually used. As a result, the obtained metal-based heteronanostructures could possess enhanced or novel optical, catalytic, magnetic, mechanical, electrical and (opto-)electronic properties, and thus benefit or extend their potential applications. We have realized the synthesis of a series of unusual phase metal-semiconductor heteronanostructures and the successful epitaxial growth of different metal nanostructures on two-dimensional nanomaterials. We will design and prepare advanced functional metal-based heteronanostructures with the combination of structure control and interface engineering.
Catalytic conversion of small molecules
With the continuous growth of global population and fast increasing of energy needs, major concerns have been raised over the energy security in the future. So far, our energy sources still mainly rely on the fossil fuels, such as coal, gas and oil, which have caused many environmental problems. Therefore, in order to guarantee a sustainable future, it is critically important and urgent to develop some fossil-free pathways to generate high-value fuels and chemicals for our daily demands and reduce the carbon dioxide emissions. To this end, we will try to develop some highly efficient catalysts that can convert small molecules (such as water, carbon dioxide and nitrogen) into high-value fuels and chemicals (such as hydrogen, hydrocarbons and ammonia) with renewable energy as the driving force. We have demonstrated the excellent electrocatalytic performance of 4H/fcc multimetallic nanostructures for the hydrogen evolution reaction as well as the oxygen evolution and alcohol oxidation reactions. We aim to increase the catalytic activity, selectivity, and durability of nanocatalysts towards many other important chemical reactions (e.g. carbon dioxide reduction reaction) with multiple strategies, such as crystal phase control, surface modification, strain engineering, defect introduction, metal-support interaction and electronic structure hybridization.