Prof. Jian-Gong Ma
Nankai University, China

Speech Title: Composite Catalysts based on Metal-Organic Frameworks

Abstract: Metal-organic frameworks (MOFs) are crystalline porous materials constructed by metal ions and organic ligands, which emerge as one of the most attractive materials in a variety of fields including gas storage/separation, sensing and pollution management. Recently, MOFs have been used in catalysis due to their unique structures and abundant metal active centers. However, it is still a great challenge to improve MOF catalysts with both high activity and high stability. To modify the catalytic activity of selected stable MOFs, we introduced highly active units including nanoparticles, nanowires, clusters and organometallic molecules inside MOF pores to obtain series composite catalysts such as Ag@MIL-101, Ru@ZIF-67, Cu2O@ZIF-8, Fe3O4@ MIL-101(Fe), and NHC-Co@MIL-100, which were used in CO2 conversion, hydrogenation of xylose and reduction of 4-nitrophenol, and synthesis of NH3 with excellent yields, selectivity, high stability and recyclability under extremely mild conditions. Besides, MOFs were also applied as “sustained-release capsules”, which could keep long pot-life during transport at ambient temperature while release active catalytic centers such as Pt for in-situ polymer formation at selected temperature. The composite catalysts exhibit combined superiority of nano-materials, single-molecules and MOFs.

Bio: Prof. Dr. Jian-Gong Ma received both Bachelor and Master degree in chemistry at Nankai University in 2003 and 2006, respectively. After recieving PhD degree in 2011 in Technische Universität Berlin, he went back to China, and joined Nankai university. Currently Jian-Gong Ma is the associate professor and Young academic leader at the department of chemistry, Nankai University. His scientific focus is the synthesis and application of metal-organic frameworks (MOFs) composites, especially in the catalytic conversion of CO2 and green synthesis of industrial and pharmacal productions.

 

Prof. Bo Yang
Northeastern University, China

Speech Title: Flat-band Photothermal Conversion Materials for Extraordinary Solar Interfacial Generation

Abstract: The shortage of freshwater resources is becoming increasingly severe due to factors such as population growth, environmental pollution, and climate change [1]. Given that over 70% of the Earth's surface is covered by oceans, seawater desalination is undoubtedly the most effective strategy to address this urgent issue. In recent years, researchers have been dedicated to exploring solar-driven interfacial water evaporation technologies based on the photothermal conversion effect [2-3], which hold broad application prospects in reducing the pressure of fossil energy consumption and environmental pollution, as well as ensuring the safe supply of clean water resources.
Obtaining photothermal conversion materials with broad absorption spectra and high absorption rates is the primary challenge in efficiently converting solar energy into thermal energy [4-6]. Based on the essence of the interaction between light and matter, this work employs first-principles calculations and experimental research to discover that the Ti-Ti dimer structure present in titanium suboxides (TinO2n-1) leads to the localization of Ti-3d electrons in real space and introduces flat-band electronic states near the Fermi level, thereby enhancing the joint density of states for electron transitions [7]. λ-Ti3O5, a metallic material, exhibits multiple flat-band electronic states originating from Ti-3d orbitals over a wide energy range near the Fermi level, resulting in a light absorption rate of 96.4% across the full solar spectrum.
Using first-principles molecular dynamics simulations, it is found that the Ti-Ti dimers on the most stable surface of λ-Ti3O5 can decompose some initially chemisorbed water molecules into hydroxyl groups (-OH) and hydrogen (H), which bind to the Ti and O atoms on the λ-Ti3O5 surface, respectively, leading to the hydroxylation of the λ-Ti3O5 surface. Moreover, the unique U-shaped groove structure of this surface facilitates rapid proton exchange, enabling the formation of metastable H3O* units within the physically adsorbed water molecule layer on the hydroxylated surface. This weakens the hydrogen bonding between water clusters containing H3O* and their surrounding water molecules. Combined with experimental validation, this fundamentally reveals the mechanism of water molecule evaporation from the λ-Ti3O5 surface in the form of clusters under light irradiation.
An evaporator with a three-dimensional porous interconnected structure was fabricated by mixing the photothermal conversion material λ-Ti3O5 with polyvinyl alcohol (PVA). Under 1 sun illumination (1 kW/m2), a water evaporation rate as high as 6.09 kg/m2/h was achieved. Furthermore, an outdoor seawater desalination and freshwater collection device was designed, which, when placed under natural sunlight at the campus of Northeastern University, achieved an average daily freshwater collection rate of 23 L/m2, demonstrating promising application prospects.

Bio: Prof. Dr. Bo Yang is a full professor in the School of Materials Science and Engineering at Northeastern University. He has long been committed to the basic research on alloy design, microstructure and property control of phase change functional materials and photothermal conversion materials. His research achievements have been published in more than 60 academic papers in internationally and domestically renowned academic journals such as Nature, Acta Materialia, and Scripta Materialia. He has given two oral reports at international academic conferences. He has undertaken 2 general projects of the National Natural Science Foundation of China and 1 sub-project of the National Key Research and Development Program. He has applied for and been granted 4 national invention patents.