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Title: Localized charge transfer in two-dimensional molybdenum trioxide
Authors: Kumar, Vipin
Liu, Liang
Nguyen, Viet Cuong
Bhavanasi, Venkateswarlu
Parida, Kaushik
Mandler, Daniel
Lee, Pooi See
Keywords: Engineering::Materials
Issue Date: 2017
Source: Kumar, V., Liu, L., Nguyen, V. C., Bhavanasi, V., Parida, K., Mandler, D. & Lee, P. S. (2017). Localized charge transfer in two-dimensional molybdenum trioxide. ACS Applied Materials & Interfaces, 9(32), 27045-27053.
Project: NRF-NRFI-2016-05
Journal: ACS Applied Materials & Interfaces 
Abstract: 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.
ISSN: 1944-8244
DOI: 10.1021/acsami.7b09641
Rights: © 2017 American Chemical Society (ACS). All rights reserved.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:MSE Journal Articles

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