Keggin‐Type Polyoxometalate Modified Ag/Graphene Composite Materials for Electrocatalytic Water Oxidation

Here, two new polyoxometalate (POM)‐based biimidazole (H 2 biim) complexes formulated as [Ag(H 2 biim) 2 ] 2 [Ag 4 (H 2 biim) 4 ][(PW 12 O 40 ) 2 ] ( 1 ) and [Ag(H 3 biim) 2 ][PW 12 O 40 ] · 4H 2 O ( 2 ) were synthesized by a hydrothermal method, and their structures were determined by single‐crystal X‐ray diffraction and other physico‐chemical and spectroscopic methods. Furthermore, by using 1 and 2 as precursors, graphene as a carrier and N,N‐dimethylformamide (DMF) as a reducing agent, two kinds of POM and Ag nanoparticle with high dispersion loaded graphene composite materials (denoted as PW 12 /Ag/graphene‐a and PW 12 /Ag/graphene‐b, respectively) were prepared through a one‐step synthesis method. PW 12 /Ag/graphene‐a and PW 12 /Ag/graphene‐b were applied in electrocatalytic water oxidation in neutral media and obtained lower overpotentials than the reference electrodes including Ag/graphene, PW 12 /graphene, and PW 12 /Ag/graphene owing to a synergistic role of the three components. The composite electrodes display good stability. This work provides new insight for preparing water oxidation catalysts using Ag‐based POMs as precursors.