Localized Charge Transfer in Two-Dimensional Molybdenum Trioxide

Vipin Kumar, Liang Liu, Viet Cuong Nguyen, Venkateswarlu Bhavanasi, Kaushik Parida, Daniel Mandler, Pooi See Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Molybdenum trioxide is an interesting inorganic system in which the empty 4d states have potential to hold extra electrons and therefore can change states from insulating opaque (MoO3) to colored semimetallic (HxMoO3). Here, we characterize the local electrogeneration and charge transfer of the synthetic layered two-dimensional 2D MoO3-II (a polymorph of MoO3 and analogous to α-MoO3) in response to two different redox couples, i.e., [Ru(NH3)6]3+ and [Fe(CN)6]3- by scanning electrochemical microscopy (SECM). We identify the reduction of [Ru(NH3)6]3+ to [Ru(NH3)6]2+ at the microelectrode that leads to the reduction of MoO3-II to conducting blue-colored molybdenum bronze HxMoO3. It is recognized that the dominant conduction of the charges occurred preferentially at the edges active sites of the sheets, as edges of the sheets are found to be more conducting. This yields positive feedback current when approaching the microelectrode toward 2D MoO3-II-coated electrode. In contrast, the [Fe(CN)6]4-, which is reduced from [Fe(CN)6]3-, is found unfavorable to reduce MoO3-II due to its higher redox potential, thus showing a negative feedback current. The charge transfer on MoO3-II is further studied as a function of applied potential. The results shed light on the charge transfer behavior on the surface of MoO3-II coatings and opens the possibility of locally tuning of their oxidation states.

Original languageAmerican English
Pages (from-to)27045-27053
Number of pages9
JournalACS applied materials & interfaces
Issue number32
StatePublished - 16 Aug 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.


  • localized charge transfer
  • microelectrode
  • molybdenum trioxide
  • redox couple
  • scanning electrochemical microscopy


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