Photochemically-Assisted Synthesis of Birnessite Nanosheets and Their Structural Alteration in the Presence of Pyrophosphate

Haesung Jung, Tandeep S. Chadha, Yujia Min, Pratim Biswas, Young Shin Jun

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Recent findings have showed the environmental abundance of soluble Mn(III)-complexes (e.g., Mn-siderophore and Mn(III)-pyrophosphate (Mn(III)-PP)). Specifically, Mn(III)-PP is of emerging interest in understanding Mn redox cycling and phosphorus cycling in catalysis and environmental systems. Curiously, however, further oxidation of Mn(III)-PP and consequent formation of a MnO2 solid phase have not been considered yet. Here, using photochemically-assisted fast oxidation of Mn2+ (aq) by the reaction with superoxide, generated from nitrate photolysis, we report the role of PP in formation of disordered δ-MnO2 nanosheets and changes in their stacking and structures. With increasing PP concentrations from 0.3 to 2 mM, δ-MnO2 nanosheets showed better stacking (thicker) layers and an alteration from hexagonal to orthogonal structure (more Mn(III) in layers). We found that the amount of Mn(III)-PP complex and the formation rate of δ-MnO2 nanosheets under the different PP concentrations affected both their layer structures and stacking behaviors. These findings open a new possibility of using photochemically-assisted green chemistry to control the properties of disordered δ-MnO2 birnessite nanosheets for use in more effective catalytic reactions, such as water oxidation, and suggest the importance of Mn(III)-PP complexes for the formation of δ-MnO2 nanosheets in nature.

Original languageEnglish (US)
Pages (from-to)10624-10632
Number of pages9
JournalACS Sustainable Chemistry and Engineering
Issue number11
StatePublished - Nov 6 2017
Externally publishedYes


  • Manganese
  • Mn(III)-pyrophosphate
  • Nanosheets stacking
  • Nitrate
  • Pair distribution function
  • Sunlight
  • Superoxide

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment


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