A Bioinspired Molecular Polyoxometalate Catalyst with Two Cobalt(II) Oxide Cores for Photocatalytic Water Oxidation

Abstract

To overcome the bottleneck of water splitting, the exploration of efficient, selective, and stable water oxidation catalysts (WOCs) is crucial. We report an all-inorganic, oxidatively and hydrolytically stable WOC based on a polyoxometalate [(A-α-SiW9 O34)2Co8(OH)6(H2O)2(CO3)3](16-) (Co8 POM). As a cobalt(II)-based cubane water oxidation catalyst, Co8POM embeds double Co(II)4O3 cores. The self-assembled catalyst is similar to the oxygen evolving complex (OEC) of photosystem II (PS II). Using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, Co8POM exhibits excellent water oxidation activity with a turnover number (TON) of 1436, currently the highest among bioinspired catalysts with a cubical core, and a high initial turnover frequency (TOF). Investigation by several spectroscopy, spectrometry, and other techniques confirm that Co8POM is a stable and efficient catalyst for visible light-driven water oxidation. The results offer a useful insight into the design of water oxidation catalysts.

Recent Advances in First‐Row Transition Metal Clusters for Photocatalytic Water Splitting

“…These POMs can be regarded as multidentate O‐donor ligands due to the affluent oxygen on the surfaces and used to construct various transition metal POM clusters. Combining 3d‐metal ions with POMs not only can help regulate the band gap, but also may broaden the absorption spectrum . Therefore, a number of heterometallic 3d‐POMs have recently been investigated, such as Co, Ni, Cu, Mn and Fe‐based POMs.…”

“…Combining 3d-metal ions with POMs not only can help regulate the band gap, but also may broaden the absorption spectrum. [77][78][79][80][81][82] Therefore, a number of heterometallic 3d-POMs have recently been investigated, such as Co, Ni, Cu, Mn and Febased POMs. Thanks to multiple redox active metal sites, such clusters are widely used in photocatalytic water splitting.…”

Catalysts Based on Earth‐Abundant Metals for Visible Light‐Driven Water Oxidation Reaction

“…As some Mn POMs with cubic (M 4 O 4 ) or defective cubic (M 4 O 3 ) core structure were reported capable of catalyzing water oxidation, we hope to improve the activity of transition metal‐based POMs by constructing multiple active water oxidation sites. For example, [(A‐α‐SiW 9 O 34 ) 2 Co 8 (OH) 6 (H 2 O) 2 (CO 3 ) 3 ] 16− ( 3 ) is a self‐assembled octanuclear cobalt complex that consist of defective cubic core units that are similar to Mn 4 CaO 5 in OEC of plants (Figure ) . One terminal aqueous ligand was coordinated to one of the four Co ions in each defective Co II 4 O 3 cubic core.…”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…By leveraging the electrochromic properties of Well-Dawson-type polyoxometalates based on K 10 231 The electrochromic properties are available in K 6 P 2 W 18 O 62 when it is combined with TiO 2 nanowires, resulting in excellent switching and transmittance properties. 232 Polyoxotungstates have been employed in a number of energy conversion and storage applications 36,43,228,[233][234][235][236][237][238][239][240][241][242] and sensors. 145,[243][244][245][246][247] 6 | POLYOXOMOLYBDATE Molybdenum trioxide with the formula MoO 3 has been applied as catalysts and synthesizing agent, and its polyoxometalate counterpart polyoxomolybdate has been widely studied to modulate their electronic and optoelectronic properties for energy conversion and storage applications.…”