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- Title
Photochemical, Electrochemical, and Photoelectrochemical Water Oxidation Catalyzed by Water-Soluble Mononuclear Ruthenium Complexes.
- Authors
Li, Ting ‐ Ting; Zhao, Wei ‐ Liang; Chen, Yong; Li, Fu ‐ Min; Wang, Chuan ‐ Jun; Tian, Yong ‐ Hua; Fu, Wen ‐ Fu
- Abstract
Two mononuclear ruthenium complexes [Ru- (H2tcbp)(isoq)2] (1) and [Ru(H2tcbp)(pic)2] (2) (H4 tcbp= 4,4',6,6'-tetracarboxy-2,2'-bipyridine, isoq=isoquinoline, pic=4-picoline) are synthesized and fully characterized. Two spare carboxyl groups on the 4,4'-positions are introduced to enhance the solubility of 1 and 2 in water and to simultaneously allow them to tether to the electrode surface by an ester linkage. The photochemical, electrochemical, and photoelectrochemical water oxidation performance of 1 in neutral aqueous solution is investigated. Under electrochemical conditions, water oxidation is conducted on the deposited indium-tin-oxide anode, and a turnover number higher than 15,000 per water oxidation catalyst (WOC) 1 is obtained during 10 h of electrolysis under 1.42 V vs. NHE, corresponding to a turnover frequency of 0.41 s-1. The low overpotential (0.17 V) of electrochemical water oxidation for 1 in the homogeneous solution enables water oxidation under visible light by using [Ru(bpy)3]2+ (P1) (bpy=2,2'-bipyridine) or [Ru(bpy)2(4,4'-(COOEt)2-bpy)]2+ (P2) as a photosensitizer. In a three-component system containing 1 or 2 as a lightdriven WOC, P1 or P2 as a photosensitizer, and Na2S2O8 or [CoCl(NH3)5]Cl2 as a sacrificial electron acceptor, a high turnover frequency of 0.81 s-1 and a turnover number of up to 600 for 1 under different catalytic conditions are achieved. In a photoelectrochemical system, the WOC 1 and photosensitizer are immobilized together on the photoanode. The electrons efficiently transfer from the WOC to the photogenerated oxidizing photosensitizer, and a high photocurrent density of 85 μAcm-2 is obtained by applying 0.3 V bias vs. NHE.
- Subjects
HYDROPHILIC compounds; MOLECULAR structure of ruthenium compounds; PHOTOCHEMISTRY; PHOTOELECTROCHEMISTRY; CARBOXYL group
- Publication
Chemistry - A European Journal, 2014, Vol 20, Issue 43, p13957
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201403872