Efficient Electrocatalytic Water Oxidation by a Dinuclear Ruthenium(II) Complex with Vicinal Aquo and Hydroxo Groups Adsorbed on a TiO2 Electrode
Efficient Electrocatalytic Water Oxidation by a Dinuclear Ruthenium(II) Complex with Vicinal Aquo and Hydroxo Groups Adsorbed on a TiO2 Electrode
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TiO2 电极上吸附有邻位水基和羟基的双核钌 (II) 络合物的高效电催化水氧化
DOI：
10.1021/acsaem.0c02242
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发表时间：
2020
影响因子：
6.4
通讯作者：
Yagi Masayuki
中科院分区：
文献类型：
--
作者：
Tanahashi Yuki;Nagai Sho;Tsubonouchi Yuta;Hirahara Masanari;Sato Taisei;Mohamed Eman A.;Zahran Zaki N.;Saito Kenji;Yui Tatsuto;Yagi Masayuki
双核钌（II）配合物，邻位，邻位-[Ru 2（Hcptpy）2L（μ-Cl）]3+（Ru2（μ-Cl），Hcptpy = 4′-（4-carboxyphenyl）-2，2 ′; 6′，2 ″-三联吡啶和L = 5-苯基-2，8-二（2-吡啶基）-1，9，10-蒽啶）和近端，近端-[Ru 2（cptpy）2L（OH）（OH 2）]+（Ru 2（OH）（OH 2）），借助于单核钌（II）络合物的定量光异构化来合成，[Ru（Hcptpy）L（OH 2）]2+（d-RuOH 2）. Ru 2（μ-Cl）和Ru 2（OH）（OH 2）通过4-羧基苯基连接基团化学吸附在纳米多孔TiO 2电极上，在磷酸盐缓冲溶液中加入0.1M KPF 6后，由于这些配合物的PF 6盐在水中的溶解度较低，它们在电极上的稳定性得到了显著提高。在1.6V下，对饱和甘汞电极（SCE）的催化电流为5.1mA·cm-2。这表明Ru 2（OH）（OH 2）中每个Ru中心上具有邻位OH 2和OH-配体的双核结构对于高效的水氧化催化非常重要。在1.16 V（SCE）下，Ru 2（OH）（OH 2）/TiO 2电极的体电解中，O2的释放效率为87%（法拉第）。电催化后，75%的Ru 2（OH）（OH 2）以Ru 2 II（OH）（OH 2）（或Ru 2 II（OH）2）和Ru 2 III（OH）2的形式留在电极上，21%的Ru 2 III（OH）2和/或Ru 2 IV（O）（OH）以较高的氧化态被洗脱到电解质溶液中，即使加入KPF 6对络合物洗脱的抑制作用仍然保持不变.机理研究揭示了重要的催化方面，涉及活性Ru 2 IV（O）（OH）状态，这可能是负责通过在电极表面上的氧代的分子内偶联的O-O键的形成。
Dinuclear ruthenium(II) complexes,proximal,proximal-[Ru2(Hcptpy)2L(μ-Cl)]3+(Ru2(μ-Cl), Hcptpy = 4′-(4-carboxyphenyl)-2,2′;6′,2″-terpyridine and L = 5-phenyl-2,8-di(2-pyridyl)-1,9,10-anthyridine) andproximal,proximal-[Ru2(cptpy)2L(OH)(OH2)]+(Ru2(OH)(OH2)), were synthesized with the aid of quantitative photoisomerization of a mononuclear ruthenium(II) complex,distal-[Ru(Hcptpy)L(OH2)]2+(d-RuOH2).Ru2(μ-Cl) andRu2(OH)(OH2)were chemically adsorbed on a nanoporous TiO2electrode via 4-carboxyphenyl linker moieties on the complexes, and the stability of these complexes adsorbed on the electrode was considerably improved by addition of 0.1 M KPF6in a phosphate buffer solution due to the low solubility of PF6salts of these complexes in water.Ru2(OH)(OH2)worked efficiently for electrocatalytic water oxidation on the electrode with an overpotential (ηO2) of 530 mV at a pH of 7.0 and a high catalytic current of 5.1 mA cm–2at 1.6 V versus saturated calomel electrode (SCE) compared withRu2(μ-Cl). This suggests that the dinuclear structure with vicinal OH2and OH–ligands on each Ru center inRu2(OH)(OH2)is important for efficient water oxidation catalysis. In bulk electrolysis at 1.16 V versus SCE using theRu2(OH)(OH2)/TiO2electrode, O2was evolved with 87% of Faraday efficiency. After the electrocatalysis, 75% ofRu2(OH)(OH2)remained on the electrode in Ru2II(OH)(OH2) (or Ru2II(OH)2) and Ru2III(OH)2states, and 21% was eluted to the electrolyte solution in the higher oxidation states of Ru2III(OH)2and/or Ru2IV(O)(OH), even with the suppression effect on the complex elusion by addition of KPF6maintained. The mechanistic investigation revealed the important catalytic aspect involving the active Ru2IV(O)(OH) state, which could be responsible for the O–O bond formation by intramolecular coupling of their oxos on the electrode surface.