5 years ago

Covalent bonds immobilization of cofacial Mn porphyrin dimers on an ITO electrode for efficient water oxidation in aqueous solutions

Covalent bonds immobilization of cofacial Mn porphyrin dimers on an ITO electrode for efficient water oxidation in aqueous solutions
We previously reported several manganese porphyrin dimers as the first manganese-containing molecular catalysts for water oxidation, however, in non-aqueous CH3CN solution containing 5% H2O. Here, we successfully fabricated these dimers with mono- and hexaphosphonic acid groups, Mn2DP-PO3H2 and Mn2DP-(PO3H2)6, to covalently assemble them on the surface of ITO electrode (ITO=indium-doped tin oxide) and use the Mn2DP-PO3H2 and Mn2DP-(PO3H2)6|ITO assemblies as heterogeneous catalysts for electrochemical water oxidation in aqueous buffer solutions. The mono-phosphonic acid fabricated assemblies showed unprecedent high turnover frequencies (TOFs) (up to 44.9s−1) at a low overpotential (η =0.47V) in a neutral buffer solution. In acidic buffered solutions (pH = 1.5), they showed higher TOFs (up to 47.4s−1) at a very low overpotential (η =0.26V). The robustness of the mono-phosphonic acid fabricated catalysts, Mn2DP-PO3H2|ITO, was tested at a high overpotential (η =0.80V). Although they showed an oxygen evolution with 178.3s−1 TOF, the oxygen evolution completely stopped after 11h electrolysis. UV–vis spectra monitored during the electrolysis clearly indicated the gradual detachment of the catalysts from the ITO surface is likely the main reason of stopping the oxygen evolution. The hexa-phosphonic acid catalyst assembly, Mn2DP-(PO3H2)6|ITO, however, showed a continuous oxygen evolution without stopping even after 23h of electrolysis with 199.3s−1 TOF. Tafel plots in different pHs give insights on the mechanism of H2O oxidation.

Publisher URL: www.sciencedirect.com/science

DOI: S002195171730194X

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.