A novel high-efficiency mercury removal photocatalyst. **Beijing Institute of Technology Press, LLC.
Scientists from the School of Energy and Mechanical Engineering at Shanghai Electric Power University have developed a new and efficient photocatalyst for mercury removal.
They published their research in Advances in Energy Materials.
It is imperative to develop energy-efficient, safe and sustainable photocatalytic mercury removal technologies," said Wu Jiang, author and professor at the School of Energy and Mechanical Engineering at Shanghai Electric Power University. "Currently, thermocatalytic technologies occupy the majority of the market, but they are limited in terms of manufacturing cost and sustainability. ”
Mr. Wu explained that as an alternative to thermocatalytic technology, photocatalytic technology has several significant advantages, especially as a photocatalytic mercury removal technology for flue gas, which can effectively control mercury emissions in flue gas.
Photocatalytic technology uses the principle of converting solar energy into chemical energy, which has great potential in solving the problem of air pollution, and is environmentally friendly, energy-saving, safe, and sustainable," Wu said.
Photocatalytic oxidative mercury removal technology [utilizes] the generation of reactive free radicals under visible light, [oxidizes] mercury 0H2+, and [uses] existing air pollution equipment to remove mercury. The technology has no secondary pollution, good stability, and has been gradually applied in pollutant control.
However, photocatalytic technology cannot simply be exchanged with thermocatalytic technology to remove mercury from flue gases. Efficient mercury removal photocatalysts need to meet the following conditions:
1) The band gap is small, which can improve the response spectral range and improve the utilization rate of light energy.
2) It should be ensured that the valence band potential of the material is corrected compared to the potential that can produce strong oxidizing substances, and the conductive potential of the material should be more negative than the potential that can produce strong oxidizing substances.
3) More active sites: The current view of the catalytic community is that the active site has the highest photocatalytic activity, so a larger specific surface area is needed to load more active sites and improve the activity of the photocatalyst.
4) The higher carrier lifetime, the photon excites the electron transition, producing electron-hole pairs, once the electron and the hole are recombined in vivo, the catalytic reduction reaction will not be able to occur, so increasing the carrier lifetime is to improve the probability of electron-hole reaction with mercury. According to Wu, there is still a long way to go in the development and improvement of photocatalytic mercury removal technology.
Wu Jiang and his team reviewed previous work and developed a series of bismuth-based photocatalytic mercury removal materials. "The strategy of constructing heterojunctions can effectively adjust the energy level structure of the composite photocatalyst, optimize the photoresponse performance, and accelerate the efficient transport and separation of carriers. ”
In this work, we introduced defect engineering and coupled G-C3N5 to further improve the photocatalytic mercury removal performance of bismuth-based materials. The research results provide theoretical support for the application of G-C, and the application of 3N5 and its composites in the field of mercury removal in flue gas.
In order to develop reliable and stable photocatalytic mercury removal materials, we constructed a G-C3N5Bi5O7I composite photocatalyst by calcination.
The composite's unique Z-shaped heterojunction structure has nitrogen and oxygen vacancies, which facilitate the efficient separation and migration of electrons and holes. Mr. Wu said. In this paper, a photocatalytic mercury removal reaction mechanism based on the co-processing of built-in electric field and defect structure is proposed. This work opens up a new approach for the synthesis and development of G-C 3N5 photocatalytic heterojunction materials".
More information: Weiqun Chu et al, Z-scheme heterojunction g-c 3 n 5 bi 5 o 7 i high-efficiency mercury removal photocatalyst, Advances in Energy Materials (2023).doi： 10.34133/energymatadv.0064