Polyelectrolyte-Assisted Oxygen Vacancies: A New Route to Defect Engineering in Molybdenum Oxide

• DOI: 10.1021/acs.langmuir.8b00539
• Publication Date: 2018-05-04T23:19:35Z
• Authors: Sajad Yazdani; Raana Kashfi-Sadabad; Tran Doan Huan; Mayra Daniela Mor...; Michael Thompson ...
• Keywords: Molybdenum oxide

The presence of oxygen vacancy sites fundamentally affects physical and chemical properties materials. In this study, a dipole-containing interaction between poly(diallyldimethylammonium chloride) PDDA α-MoO3 is found to enable high-concentrations surface vacancies. Thermal annealing under Ar resulted in negligible reduction MoO3 MoO3- x with = 0.03 at 600 °C. contrast, we show that the thermochemical reaction polyelectrolyte can significantly reduce 0.36 (MoO2.64) H2 gas enhanced substoichiometry from 0.62 0.98 by using same conditions. Density functional theory calculations, supported experimental analysis, suggest are created through absorption terminal site (Ot) upon decomposition N-C bond pentagonal ring during thermal treatment. Ot atoms absorbed as ionic O- neutral O2-, creating Mo5+-vO· Mo4+-vO·· bipolarons polarons, respectively. X-ray photoemission spectroscopy peak analysis indicates ratio charged molybdenum ions PDDA-processed samples increased Mo4+/Mo6+ 1.0 Mo5+/Mo6+ 3.3 when reduced 400 °C 3.7 2.6 This consistent our ab initio calculation where formation energy 0.22 eV higher than for bulk material 0.02 on surface. study reveals new paradigm effective enhancement concentrations essential variety technologies including advanced conversion applications such electrochemical storage, catalysis, low-temperature water splitting.