XPS studies on the Mo oxide-based coatings electrodeposited from highly saturated acetate bath

The possibility to use highly saturated acetate bath to electrodeposit
the mixed-phase materials containing Mo oxides has been investigated.
The XRD characterization revealed that the as-deposited coatings are
amorphous and consist only of MoO2 and MoO3 phases without traces
of metallic Mo phase. This statement has been supported by XPS measurements,
which reveal the presence of three different molybdenum
oxidations states in electrodeposits: Mo4+, Mo5+ and Mo6+. It was found
that the Mo6+ state prevails with 41% of total contribution, whilst Mo5+
and Mo4+ contribute to 28 and 31%, respectively. The deposits retain an
amorphous structure up to 800°C; while molybdenum at this temperature
is predominantly oxidized to the Mo6+ state (91%). These results,
coupled to those of SEM and EDS, revealed that concentrated acetate
bath could be used mainly for the formation of the mixed valence molybdenum
oxide film unlike to the deposition of the metallic Mo phase.