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Evolution of Anodic Product from Molybdenum Metal in Absolute Ethanol and Humidity Sensing under Ambient Conditions
journal contribution
posted on 2019-08-21, 21:03 authored by Chengsheng Ni, Darragh Carolan, Jianing Hui, Conor Rocks, Dilli Padmanaban, Jiupai Ni, Deti Xie, Zeguo Fang, John Irvine, Paul Maguire, Davide MariottiRoom-temperature
nonaqueous synthetic routes turn out to be particularly
competitive among all the available liquid-phase synthetic methods
for nanometer-sized metal oxides for multiple applications. Microplasma-assisted
anodization is employed to prepare soluble and crystalline Mo species
in a water-deficient and extraneous ionic-salt-free ethanol electrolyte.
The anodization of Mo in absolute ethanol is found to produce Mo oxyethoxide
in the liquid ethanol phase, along with a small montage of mixed hexagonal
and orthorhombic MoO3 crystals. The evolution of Mo species
in solid and liquid phases is characterized to study the crystallization
of MoO3 crystal and the formation of blue spherical Mo
polyoxometalates (POMs) after extended aging. The addition of water
in the suspension delayed the formation of molybdenum blue while hydrogen
peroxide induced the precipitation of a dendritic framework of hexagonal
MoO3. A thin MoO3 film was produced from the
solution and can be used for humidity sensing by the facile conductivity
measurement.