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Title: Environmental TEM study of electron beam induced electro-chemistry of Pr₀̣₆₄Ca₀̣₃₆MnO₃ catalysts for oxygen evolution

Environmental Transmission Electron Microscopy (ETEM) studies offer great potential for gathering atomic scale information on the electronic state of electrodes in contact with reactants but also pose big challenges due to the impact of the high energy electron beam. In this article, we present an ETEM study of a Pr₀̣₆₄Ca₀̣₃₆MnO₃ (PCMO) thin film electro-catalyst for water splitting and oxygen evolution in contact with water vapor. We show by means of off-axis electron holography and electrostatic modeling that the electron beam gives rise to a positive electric sample potential due to secondary electron emission. The value of the electric potential depends on the primary electron flux, the sample -conductivity and grounding, and gas properties. We present evidence that two observed electro-chemical reactions are driven by a beam induced electrostatic potential of the order of a volt. The first reaction is an anodic electrochemical oxidation reaction of oxygen depleted amorphous PCMO which results in recrystallization of the perovskite structure. The second reaction is oxygen evolution which can be detected by the oxidation of a silane additive and formation of SiO2–x at catalytically active surfaces. Recently published in-situ XANES observation of subsurface oxygen vacancy formation during oxygen evolution at a positive potential [³²]more » is confirmed in this work. The quantification of beam induced potentials is an important step for future controlled electro-chemical experiments in an ETEM.« less
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [3] ;  [3] ;  [4] ;  [5] ;  [1]
  1. Univ. of Goettingen, Goettingen (Germany). Inst. of Materials Physics
  2. Technical Univ. of Denmark, Lyngby (Denmark). Center for Electron Nanoscopy; Helmholtz-Zentrum Berlin (HZB), (Germany). German Research Centre for Materials and Energy
  3. Technical Univ. of Denmark, Lyngby (Denmark). Center for Electron Nanoscopy
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Center for Electron Microscopy
  5. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics, Materials Science Dept., and Center for Functional Nanomaterials
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 1932-7447; R&D Project: MA015MACA; KC0201010
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 119; Journal Issue: 10; Journal ID: ISSN 1932-7447
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY Environmental Transmission Electron Microscopy (ETEM); thin film electro-catalyst; perovskite structure