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Welcome on the website of the Protoelectric Potential Map (PPM), the two dimensional display of unified pH scale and unified redox scale.



PPM in brief:

  • the unified acidity pHabs is defined by the absolute chemical potential of the proton
  • the unified reducity (redox potential) peabs is defined by the absolute chemical potential of the electron
  • both scales are connected by the Hydrogen Evolution Reaction (HER)
  • peabs is plotted vs. pHabs
  • this plot is suitable to compare acidities and reducities of redox- and/or protoacitve species in different media


For a detailed description, please see:

Radtke, V., D. Himmel, K. Pütz, S.K. Goll and I. Krossing (2014) The protoelectric potential map (PPM): an absolute two-dimensional chemical potential scale for a global understanding of chemistry. Chemistry 20, 4194–4211.

or follow the link below: null null 


The PPM-project is funded by the DFG and the European Research Council with the ERC Advanced Grant "UniChem", No. 291383


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