Development of polyoxometalate-based Ag-H 2 biim inorganic-organic hybrid compounds functionalized for the acid electrocatalytic hydrogen evolution reaction.

The electrocatalytic hydrogen evolution reaction (HER) is an ideal method for hydrogen production. Transition metal complex electrocatalysts exhibit poor HER activity due to excessive or weak adsorption of H during the electrochemical reduction of water to molecular hydrogen in acidic environments. Developing specific functional complex materials as desired catalysts is challenging. Here, an electrochemical surface restructuring strategy of polyoxometalate (POM)-modified Ag materials toward the HER with a dramatically decreased overpotential under acidic aqueous conditions is established. We prepared two POM [SiW 12 O 40 ] 4- (SiW 12 )/[P 2 W 18 O 62 ] 6- (P 2 W 18 )-based Ag-2,2'-biimidazole (H 2 biim) inorganic-organic hybrid compounds (1 and 2) via the hydrothermal method and these two compounds undergo an electrochemical restructuring process in 0.5 M H 2 SO 4 during the HER, in which Ag nanoparticles are in situ formed with the basic structures of SiW 12 and P 2 W 18 being maintained. The activated catalysts (1-AC-RDE and 2-AC-RDE) exhibit good electrocatalytic activity for the HER with good long-term stability, and the required overpotentials at a current density of 10 mA cm -2 are 112 mV (1-AC-RDE) and 91 mV (2-AC-RDE) with Tafel slopes of 77 mV dec -1 and 65 mV dec -1 , respectively. The excellent electron-proton storage and transferability of SiW 12 and P 2 W 18 may provide a solution for the insufficient capture of H by Ag, leading to an effective self-optimizing behavior and superior acidic HER activity.