Snapshot of interacting gas atoms on metal-organic crystals

Metal-organic frameworks (MOFs) are nanoporous crystals made from inorganic and organic compounds. They efficiently adsorb and store gases such as hydrogen, methane and carbon dioxide. But it is largely unknown how the adsorbed gas atoms interact among themselves within and across pores in MOFs. 

An international team of researchers from Saudi Arabia, Korea, China, Sweden and the US has now gained new insights into how gas atoms adsorbed onto different MOF crystals interact and behave among themselves at precisely controlled temperatures and pressures¹. 

The team, led by Osama Terasaki and Omar M. Yaghi, had observed that the interactions between adsorbed argon gas atoms occurred at five different stages.   

On increasing the pressures of argon gas, the adsorbed argon atoms gathered in certain pore regions in higher numbers than the average, indicating the formation of extra adsorption domains in the MOF crystals. In addition, the adsorbed argon atoms formed a superlattice structure with nanodomains. On further increasing argon pressures, both the extra domains and superlattice structure disappeared at the end of stage 4.  

Similar patterns of interactions and behaviour were observed when the adsorption of nitrogen and carbon dioxide were studied, the researchers say. “Insights gleaned from this study will help synthesize better MOF crystals with enhanced gas-storing capacities,” says Terasaki. 

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