Abstract
Subnanometer materials, as an ideal platform for constructing strongly coupled interfaces at the atomic/cluster scale, are at the core of advancing efficient energy conversion technologies due to their ultimate atomic utilization efficiency, quantum confinement effects, and high specific surface area. The strongly coupled sub-nano interfacial structures developed based on such materials can simultaneously enhance the activity, selectivity, and durability of catalysts, holding the potential to overcome the limitations of traditional nanocatalysts in terms of atomic utilization and catalytic performance. However, the controllable synthesis of these materials remains challenging, constrained by the heavy reliance of traditional solvothermal methods on solvents, their high environmental footprint, and slow thermodynamic processes, making it difficult to capture metastable subnanometer structures. To address the controllable preparation of these materials, solvent-free microwave synthesis has emerged. This technique leverages the selective absorption of microwave energy by polar functional groups to generate transient high temperatures and ultrafast kinetics under solvent-free conditions, bypassing traditional thermodynamic limitations and providing a novel pathway for the precise synthesis of metastable subnanometer structures. This article systematically elaborates on the synthesis principles, research progress, and application prospects of such materials, aiming to provide theoretical support for the further development and industrialization of high-performance subnano catalytic materials.