Bioinspired inhibition of aggregation in metal-organic frameworks (MOFs)

Different from traditional procedures of using solid stabilizers like polymers and surfactants, here we demonstrate that water, as a very "soft" matter, could function as a "spacer" to prevent the aggregation of metal-organic frameworks (MOFs) in aqueous dispersions. Our theoretical calculations reveal in case of an excess of positively charged metal nodes of MOFs, where water molecules are ligated to metal nodes that greatly enhance MOFs' solution dispersibility through electrostatic stabilization. This discovery has motivated us to develop a facile experimental approach for producing a category of "clean" MOF dispersions without foreign additives. Potential application has been demonstrated for the size fractionation of MOFs, which results in small-size MOFs (50-80 nm) characteristic of superior electrocatalytic oxygen evolution activities (256 mV at 10 mA cm^-2, Tafel slope of 49 mV dec^-1 and durability >30 h). This work would provide new clues for aqueous processing of MOFs for many emerging applications.