报告人：Prof. Yugang Sun (Temple University, USA)
报告题目：“Quantum-Sized” Metal Nanoparticles for Photochemical Energy Conversion
Generation of hot carriers in transition metal catalysts through photoexcitation has been demonstrated to be a promising approach capable of significantly lowering activation temperature of the catalysts and improving the selectivity of heterogeneous catalysis. Platinum-group metals (PGMs) such as Pt, Pd, Ru or Rh are excellent catalytic materials but exhibit SPR in the ultraviolet (UV) spectral region, which represents a significant disadvantage for photocatalysis due to the poor overlap with the solar spectrum. Although increasing size of PGM nanoparticles shifts SPR absorption to the red, it increases cost and reduces surface area and thus catalytic activity. Moreover, increasing the size of metal nanocrystals significantly reduces the yield of hot electron generation, lowering the efficiency of photochemical energy conversion. In this presentation, a new light absorption model will be discussed to demonstrate a transformative way to enhance optical absorption in small PGM nanoparticles in the visible spectral region by adjusting their dielectric environment instead of changing their size. In this model, the “quantum-sized” metal nanocrystals are attached to surfaces of transparent silica spheres, which can support a variety of dielectric scattering resonances (e.g., Fabry-Perot or Whispering Gallery modes depending on the size of silica spheres) capable of creating strong electric fields near the silica surface. The intensified nearfields can dramatically enhance the absorption cross-section of the metal nanocrystals, which are on the silica surface, thus improving the yield of “hot electrons” in the metal nanocrystals. This new model provides a unique opportunity to efficiently generate hot carriers in the PMG metal nanoparticles upon excitation of solar energy.
Yugang Sun教授，2001年于中国科学技术大学获得博士学位，2001年至2006年先后在美国华盛顿大学、伊利诺伊斯大学从事研究工作，2006年后到美国阿贡国家实验室工作，2015年加入天普大学。Yugang Sun教授多年从事新型金属纳米材料的构筑及应用研究，在纳米制造、原位表征、催化、储能等多个领域取得了创新性科研成果。