The race of time during oxide-to-MOF conversion: Competition between MOF(Al) growth and alumina facets rearrangement

The direct growth of Metal-Organic-Frameworks (MOFs) on ceramic substrates is a promising strategy to promote their industrial implementation. Yet, the lack of deep scientific comprehension regarding the in-situ conversion of metal derivatives into MOFs, resulting in limited control over their crystal growth, morphology and distribution, hampers their up-scale production. In this work, we provide for the first time the experimental evidence that a competition between MOF formation and alumina facet rearrangement occurs at extended reaction times up to 90 min. We demonstrate that the facet rearrangement induced by pH variations dictates the final morphology and distribution of MOF(Al) crystals grown during the MW-assisted hydrothermal synthesis in water. Hence when facet-rich alumina substrate is used for oxide-to-MOF conversion, short reaction times ought to be applied.