Autogenous Production and Stabilization of Highly Loaded Sub‐Nanometric Particles within Multishell Hollow Metal–Organic Frameworks and Their Utilization for High Performance in Li–O2 Batteries

Sub‐nanometric particles (SNPs) of atomic cluster sizes have shown great promise in many fields such as full atom‐to‐atom utilization, but their precise production and stabilization at high mass loadings remain a great challenge. As a solution to overcome this challenge, a strategy allowing synthesis and preservation of SNPs at high mass loadings within multishell hollow metal–organic frameworks (MOFs) is demonstrated. First, alternating water‐decomposable and water‐stable MOFs are stacked in succession to build multilayer MOFs. Next, using controlled hydrogen bonding affinity, isolated water molecules are selectively sieved through the hydrophobic nanocages of water‐stable MOFs and transferred one by one to water‐decomposable MOFs. The transmission of water molecules via controlled hydrogen bonding affinity through the water‐stable MOF layers is a key step to realize SNPs from various types of alternating water‐decomposable and water‐stable layers. This process transforms multilayer MOFs into SNP‐embedded multishell hollow MOFs. Additionally, the multishell stabilizes SNPs by π‐backbonding allowing high conductivity to be achieved via the hopping mechanism, and hollow interspaces minimize transport resistance. These features, as demonstrated using SNP‐embedded multishell hollow MOFs with up to five shells, lead to high electrochemical performances including high volumetric capacities and low overpotentials in Li–O2 batteries. Hydrogen affinity‐controlled water molecule transfers throughout multilayer metal–organic frameworks result in sub‐nanometric particle (SNP)‐embedded multishell hollow metal–organic frameworks (MOFs), where the multishell stabilizes SNPs by π‐backbonding allowing high conductivity and hollow interspaces that minimize transport resistance. Moreover, increasing the mass loading of SNPs within multishell hollow MOFs is demonstrated to enable higher capacities and smaller overpotentials in Li–O2 batteries.