The Deep Eutectic Solvent Precipitation Synthesis of Metastable Zn 4 V 2 O 9

• Published in: Inorganic chemistry 2022-01, Vol.61 (1), p.154-169
• Main Authors: Hong, Sangki, Cheng, Ye, Hariyani, Shruti, Li, Jingzhe, Doughty, Rachel M, Mantravadi, Aishwarya, Adeyemi, Adedoyin N, Smith, Emily A, Brgoch, Jakoah, Osterloh, Frank E, Zaikina, Julia V
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.1c02511

A precipitation method involving a deep eutectic solvent (DES)─a mixture of hydrogen bond donor and acceptor─is used to synthesize a ternary metal oxide. Without toxic reagents, precipitates consisting of Zn (OH) V O · H O and Zn (OH) (CO ) are obtained by simply introducing deionized H O to the DES solution containing dissolved ZnO and V O . Manipulation of the synthetic conditions demonstrates high tunability in the size/morphology of the two-dimensional nanosheets precipitated during the dynamic equilibrium process. According to differential scanning calorimetry and high-temperature powder X-ray diffraction, Zn V O and ZnO obtained by the annealing of the precipitate are intermediates in the reaction pathway toward metastable Zn V O . Intimate mixing of the metal precursors achieved by the precipitation method allows access to the metastable zinc-rich vanadate with unusually rapid heat treatment. The UV-vis and surface photovoltage spectra reveal the presence of sub-band gap states, stemming from the reduced vanadium (V ) center. Photoelectrochemical measurements confirm weak photoanodic currents for water and methanol oxidation. For the first time, this work shows the synthesis of a metastable oxide with the DES-precipitation route and provides insight into the structure-property relationship of the zinc-rich vanadate.