ACS Catalysis
ACS Catalysis
5 years ago

Fast Electron Transfer and •OH Formation: Key Features for High Activity in Visible-Light-Driven Ozonation with C3N4 Catalysts

Fast Electron Transfer and •OH Formation: Key Features for High Activity in Visible-Light-Driven Ozonation with C3N4 Catalysts
Angelika Brückner, Hongbin Cao, Jiadong Xiao, Yongbing Xie, Jin Yang, Jabor Rabeah
Photocatalytic ozonation of wastewater pollutants by sunlight is a highly attractive technology close to real application. Understanding this process on the atomic scale and under realistic working conditions is challenging but vital for the rational design of catalysts and photocatalytic decontamination systems. Here we study two highly active C3N4 photocatalysts (bulk C3N4 and a nanosheet-structured C3N4) under simultaneous visible-light irradiation and O3 bubbling in water by in situ EPR spectroscopy coupled with an online spin-trapping technique. The photoexcitation of electrons to the conduction band (CB-e–), their further trapping by dissolved O2 and O3, and the evolution of reactive oxygen species (ROS) have been semiquantitatively visualized. A dual role of O3 in boosting the CB-e– to •OH conversion is confirmed: (i) an inlet 2.1 mol % O3/O2 gas mixture can trap about 2–3 times more CB-e– upon aqueous C3N4 suspension than pure O2 and further produce •OH by a robust •O3–-mediated one-electron-reduction pathway (O3 → •O3– → HO3• → •OH); (ii) O3 can readily take CB-e– back from •O2– to form •O3–, thus blocking the inefficient H2O2-mediated three-electron-reduction route (O2 → •O2– → HO2• → H2O2 → •OH) but further strengthening the •O3–-mediated pathway. In the presence of 2.1 mol % O3/O2, the •OH yield increases by 17 and 5 times, and consequently, the mineralization rate constant of oxalic acid increases by 84 and 41 times over bulk C3N4 and NS C3N4, respectively. This work presents an attractive opportunity to boost the yield of ROS species (•OH) for water purification by visible-light-driven photocatalysis and provides a powerful tool to monitor complex photocatalytic reactions under practical conditions.

Publisher URL: http://dx.doi.org/10.1021/acscatal.7b02180

DOI: 10.1021/acscatal.7b02180

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.