A Structure‐Preserving, Dimensionality‐Increasing Strategy for the Stepwise Synthesis of Microporous α‐MoO ₃ with a Broad (100) Surface

Abstract Metal oxides with diverse structures and dimensionalities are typically synthesized via solid‐state or hydrothermal reactions. However, it is quite difficult to retain the structures of the starting materials when 0D metal salts or molecular clusters are used as precursors because higher‐dimensional structures form by structural reorganization through isomerization and decomposition/condensation reactions. In this study, we demonstrated a structure‐preserving, dimensionality‐increasing strategy for the synthesis of 2D α‐MoO 3 from 0D [Mo 2 O 5 (H 2 O) 6 ] 2+ species via a 1D [Mo 2 O 6 {(CH 3 ) 2 NCHO}] n intermediate while maintaining the structures of the precursors. By simple temperature‐controlled calcination, metastable crystals of α‐MoO 3 in which the (100) plane was the broad face were successfully synthesized, differing from conventional α‐MoO 3 in which the (010) plane is the broad face. In addition, the prepared metastable crystals possessed large surface areas, unusual micropores, and surface‐exposed coordinatively unsaturated Mo sites, allowing them to serve as high‐performance acid catalysts. This synthesis strategy is expected to facilitate the synthesis of metastable structures and the design of defects and surface structures at the atomic level.