TY - JOUR
T1 - Phase and Morphology Control of Hexagonal MoO3Crystals via Na+Interactions
T2 - A Raman Spectroscopy Study
AU - Vargas-Consuelos, C. Ingram
AU - Camacho-López, Marco A.
AU - Ramos-Sanchez, Victor H.
AU - Graeve, Olivia A.
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/7/13
Y1 - 2023/7/13
N2 - We present the effect of sodium ions (Na+) on the nucleation process and phase selectivity for the formation of hexagonal molybdenum trioxide crystals (h-MoO3). The phase selectivity during the reaction is attributed to the interaction of Na+ with the molecules in our precursor solution formed by metallic molybdenum dissolved in a mixture of hydrochloric and nitric acids. The vibrational characteristics of the precursor solutions were studied by Raman spectroscopy in combination with density functional theory modeling, showing the presence of [MoO2Cl3(H2O)]- ions within the solutions. The symmetric stretching vibration of the Mo-O bonds found at 962 cm-1 in [MoO2Cl3(H2O)]- proved that the addition of Na+ (in the form of dissolved NaCl) to the precursor solutions resulted only in an electrostatic interaction with the aquo (H2O) and chloro (Cl-) ligands in the complex. After heating the precursor solutions, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy of the obtained powders showed that adding NaCl contributed to the phase selectivity of the reaction, with the Na+ ions playing a vital role in the formation of h-MoO3 over other crystalline phases. Based on the nature of the molybdenum complexes found in the precursor solutions and the structural characteristics of the powders, a formation mechanism to obtain h-MoO3 is proposed. Additionally, the phase stability of h-MoO3 crystals was studied by calorimetry techniques, showing that h-MoO3 transforms to α-MoO3 at ∼649 K. These results provide important insights into phase control to selectively form hexagonal MoO3.
AB - We present the effect of sodium ions (Na+) on the nucleation process and phase selectivity for the formation of hexagonal molybdenum trioxide crystals (h-MoO3). The phase selectivity during the reaction is attributed to the interaction of Na+ with the molecules in our precursor solution formed by metallic molybdenum dissolved in a mixture of hydrochloric and nitric acids. The vibrational characteristics of the precursor solutions were studied by Raman spectroscopy in combination with density functional theory modeling, showing the presence of [MoO2Cl3(H2O)]- ions within the solutions. The symmetric stretching vibration of the Mo-O bonds found at 962 cm-1 in [MoO2Cl3(H2O)]- proved that the addition of Na+ (in the form of dissolved NaCl) to the precursor solutions resulted only in an electrostatic interaction with the aquo (H2O) and chloro (Cl-) ligands in the complex. After heating the precursor solutions, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy of the obtained powders showed that adding NaCl contributed to the phase selectivity of the reaction, with the Na+ ions playing a vital role in the formation of h-MoO3 over other crystalline phases. Based on the nature of the molybdenum complexes found in the precursor solutions and the structural characteristics of the powders, a formation mechanism to obtain h-MoO3 is proposed. Additionally, the phase stability of h-MoO3 crystals was studied by calorimetry techniques, showing that h-MoO3 transforms to α-MoO3 at ∼649 K. These results provide important insights into phase control to selectively form hexagonal MoO3.
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U2 - 10.1021/acs.jpcc.3c02821
DO - 10.1021/acs.jpcc.3c02821
M3 - Article
AN - SCOPUS:85165102771
SN - 1932-7447
VL - 127
SP - 13136
EP - 13148
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 27
ER -