posted on 2018-12-11, 00:00authored byHaiwen Dai, Ashutosh Rath, Yu Shu Hearn, Stephen J. Pennycook, Daniel H. C. Chua
Reduced
molybdenum oxide, generally MoO3–x, becomes increasingly metallic as the oxygen level decreases
during the reduction of MoO3 to MoO2. Its interesting
properties have recently intrigued research on MoO3–x in electrical and electrochemical areas. Lacking
effective tools to control the oxygen level is one of the research
difficulties for MoO3–x. Herein,
we report facile temperature-controlled synthesis of triangular MoO2 and square Mo4O11. The triangular and
square flakes showed metallic behavior with conductivity as high as
∼940 and ∼28 S/cm in DC measurement, respectively. The
decrease in oxygen level from Mo4O11 to MoO2 affected the density of states mapped in Mo 4d orbitals,
leading to higher conductivity for triangular MoO2. Further
Mott–Schottky analysis on MoO3–x regrown on carbon fiber paper (CFP) revealed hole mobility
of 105–108 cm2 V–1 s–1. The hole carriers at high frequencies are
attributed to potential oxygen acceptors, and molybdenum vacancies
resulted from limited reduction power of hydrogen.