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

Abstract

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] Figure 2. SEM image (a), TEM image (b), EDS elemental mapping (c), HRTEM image (d) of PW 12 /Ag/graphene-a.

Electron‐Sponge Nature of Polyoxometalates for Next‐Generation Electrocatalytic Water Splitting and Nonvolatile Neuromorphic Devices

“…This work gives insight into designing efficient water oxidation catalysts using redox‐active Ag‐based POMs. [ 99 ] A cobalt‐based POM architecture, [Co 4 (H 2 O) 2 (PW 9 O 34 ) 2 ] 10− , where a tetra‐cobalt core Co 4 O 4 “Co cubane to transfer electrons” was sandwiched between two oxidatively resistant tri‐lacunary phosphotungstate units [PW 9 O 34 ] 9− , was developed as a noble metal independent framework to investigate water oxidation activity. [ 100 ] There is another sandwich‐type POM architecture, Na 10 [Co 4 (H 2 O) 2 (VW 9 O 34 ) 2 ]·35H 2 O, where tetra‐cobalt core is sandwiched between two [VW 9 O 34 ] 9− units.…”

From unprecedented 2,2′-bisimidazole-bridged rare earth organometallics to magnetic hysteresis in the dysprosium congener

“…Both the protonated (H 2 bim) and deprotonated (bim 2− ) have been used in coordination chemistry. Transition metal (TM) complexes feature the ligand in its protonated (H 2 bim), [14][15][16][17][18][19][20][21][22] ligands singly deprotonated (Hbim − ) 19,24,25 or doubly deprotonated (bim 2− ) 14,17,19,21,[25][26][27][28] form. The degree of protonation affects the denticity of the ligand and provided access to mono-, 14,[16][17][18][19][20][21]25 di-, 14,15,17,21,22,[24][25][26][29][30][31] tri-, 27,32 or tetranuclear complexes 19,27,28 Chart 1.…”

“…Transition metal (TM) complexes feature the ligand in its protonated (H 2 bim), [14][15][16][17][18][19][20][21][22] ligands singly deprotonated (Hbim − ) 19,24,25 or doubly deprotonated (bim 2− ) 14,17,19,21,[25][26][27][28] form. The degree of protonation affects the denticity of the ligand and provided access to mono-, 14,[16][17][18][19][20][21]25 di-, 14,15,17,21,22,[24][25][26][29][30][31] tri-, 27,32 or tetranuclear complexes 19,27,28 Chart 1. This structural richness gave rise to a wide range of applications where the TM complexes were luminescent, 22 catalytically active, 15 or intriguing for their spin-crossover properties.…”

“…The degree of protonation affects the denticity of the ligand and provided access to mono-, 14,[16][17][18][19][20][21]25 di-, 14,15,17,21,22,[24][25][26][29][30][31] tri-, 27,32 or tetranuclear complexes 19,27,28 Chart 1. This structural richness gave rise to a wide range of applications where the TM complexes were luminescent, 22 catalytically active, 15 or intriguing for their spin-crossover properties. 14,16 The various binding modes also allowed the construction of metal-organic frameworks 28,31,32 or polyoxometallates.…”

“…14,16 The various binding modes also allowed the construction of metal-organic frameworks 28,31,32 or polyoxometallates. 15,30 Furthermore, many complexes of H 2 bim show strong ion pairing effects through hydrogen bonding of the N-H groups with anionic species, 16,20 yielding exotic N-H-bridged dimeric complexes 19 or potential applications in anion sensing. 14 By comparison, H 2 bim/bim 2− ligands are entirely unknown in molecular rare earth metal chemistry.…”