Microenvironment Regulation of Metal-Organic Frameworks to Anchor Transition Metal Ions for the Electrocatalytic Hydrogen Evolution Reaction.

Bearing triazine-centered linkers, three primitive metal-organic frameworks (MOFs) with a Zr 6 O 4 cluster have been prepared as Zr L1 (without any branch), Zr L2 (with -F), and Zr L3 (with -SCH 3 ). The electrocatalytic hydrogen evolution reaction (HER) by their pristine and transition metal-loaded (TM-loaded) forms was studied. It was found that the loading of TM ions could enhance the electrocatalytic power of these TM-loaded MOFs in HER, as reflected by their lower overpotentials and smaller Tafel slopes when compared with primitive MOFs. More importantly, the best electrocatalytic HER performance of Zr L3 -TM among all TM-loaded MOFs studied in this work highlights the effective housing of TM ions for unambiguous active sites through cooperative coordination by triazinic N and thioether pendants. This work proposes microenvironment regulation of MOFs as an effective strategy to enhance the electrocatalytic activity of MOF materials.