The polarization effect of plasmon photocatalyst charge separation discovered by Dalian Chemical

[ Instrument network instrument research and development ] Recently, the team of Academician of Chinese Academy of Sciences, Researcher Li Can of the State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and Researcher Fan Fengtao's team made new progress in surface plasmon photocatalytic interface charge separation research, revealing catalysis The quantitative relationship between the site charge concentration and the polarization angle.

Surface plasmons of metal nanoparticles have unique optical properties, such as light absorption in specific wavelength bands, and localized effects of light fields. They have attracted attention in the fields of analytical science, nanomaterials, optoelectronics, especially solar fuel synthesis. However, the lifetime of plasmon carriers is generally short, and it is difficult to match the slower chemical reaction time scale. How to effectively separate the plasmon charge on the interface and transfer it to the reaction site has become a key scientific problem in this field.

The research team used a self-developed spatially resolved surface photovoltage microscope to directly give a visual image: it was found that the surface plasmon holes were localized on the Au/TiO2 interface (J. Am. Chem. Soc., 2017). In the gold nanoparticle dimer, the team also discovered that the coupling effect-mediated plasmon charge accumulation in the nanocavity promotes the water oxidation reaction activity involving multiple protons (Natl. Sci. Rev., 2020). Based on spatially resolved surface photovoltage microscopy, the research team further discovered the polarization effect of surface plasmon photocatalyst charge separation. By changing the polarization angle of the incident light, the team systematically studied the local charge concentration at the catalytic site and obtained the polarization angle of charge separation: When the polarization angle of the incident light is perpendicular to the photocatalyst Au particle/TiO2 interface, the surface photovoltage signal is the largest, and the charge The interface injection efficiency is high; combined with angle-resolved scattering spectroscopy and theoretical simulations, the internal reasons for the polarization dependence of the charge concentration are preliminarily discussed; the water oxidation catalytic reaction is used as a probe reaction to confirm the polarization effect on the catalytic activity. This research provides a new method for the regulation of the interface charge separation of plasmon photocatalysts, and also provides thinking and knowledge for the understanding and development of plasmon properties.

Li Can’s team has long been committed to cutting-edge scientific research on solar photocatalysis, photoelectrocatalysis, electrocatalysis, and catalytic spectral characterization, and has achieved a series of results, especially on key scientific issues such as photogenerated charge separation: the heterogeneous junction charge separation mechanism (Angew. Chem. Int. Ed., 2008; Angew. Chem. Int. Ed., 2012); Photo-generated charge separation effect between crystal planes (Nature Commun., 2013); Photo-generated charge separation strategy for highly symmetric semiconductor single crystals (Energy Environ Sci., 2016); Independently developed new photo-generated charge imaging and characterization technology, and applied it to the imaging study of charge separation of photocatalytic materials at micro-nano scale (Angew. Chem. Int. Ed., 2015; Nature Energy, 2018).

Relevant research results were published in "Angew. Chem. Int. Ed." and selected as a hot paper. The research work has been funded by the National Natural Science Foundation of China, the Chinese Academy of Sciences Strategic Leading Science and Technology Project (Category B) "The Nature and Regulation of Energy Chemical Conversion", and the major research projects of the Chinese Academy of Sciences.