A new mononuclear Ru aquo complex [Ru(C8Otpy)(H2dcbpy)(OH2)]2+ with 4,4'-dicarboxy-2,2'-bipyridine (H2dcbpy) and 4'-octyloxy-2,2':6',2''-terpyridine (C8Otpy) ligands was synthesized to investigate electrocatalytic water oxidation by the complex immobilized on a mesoporous indium-doped tin oxide (meso-ITO) electrode using a multi-potential-step chronocoulospectrometric (MPSCCS) technique. UV-visible absorption spectroscopic data indicated that [Ru(C8Otpy)(dcbpy)(OH2)] (RuOH2) is deprotonated to [Ru(C8Otpy)(dcbpy)(OH)]- (RuOH) on the meso-ITO surface even at pH 5.9 of the electrolyte solution. The cyclic voltammogram (CV) of the RuOH/meso-ITO electrode showed a pH-independent redox response at E1/2 = 0.80 V vs. Ag/AgCl in the pH range of 5-12, being assigned to a non-proton-coupled 1e- redox process of RuIIOH/RuIIIOH. The MPSCCS measurement of the RuOH/meso-ITO electrode between 0.2 and 1.5 V vs. Ag/AgCl showed that RuIV species (tentatively RuIVO) exist in a steady state of the electrocatalysis in the initial stage. This suggests that the electrochemical oxidation from RuIVO to RuVO could compete with the water nucleophilic attack for O-O bond formation involved in the rate-determining step under the employed conditions. The possibility that the water nucleophilic attack on RuIVO could also compete with the electrochemical oxidation of RuIVO to RuVO was suggested by the electrocatalytic water oxidation at a low applied potential of 1.4 V prior to the formation potential of RuVO. The MPSCCS measurement at 1.4 V for 1 h showed that RuOH is gradually transformed into an alternative catalyst (most likely RuOx nanoparticles) on the electrode. The MPSCCS technique is promising to reveal the redox reactions and catalytic aspects of molecular catalysts immobilized on an electrode for water oxidation.

中文翻译：

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用单核钌水合物固定在介孔ITO电极上的电势水氧化的多步一步计时库仑光谱法。

具有4,4'-二羧基-2,2'-联吡啶（H2dcbpy）和4'-辛氧基-2,2'：6'的新单核Ru水配合物[Ru（C8Otpy）（H2dcbpy）（OH2）] 2+合成了2,2'-吡啶（C8Otpy）配体，以多步逐步计时质谱（MPSCCS）技术研究了固定在介孔铟掺杂氧化锡（meso-ITO）电极上的配合物的电催化水氧化作用。紫外可见吸收光谱数据表明，即使在室温下，[Ru（C8Otpy）（dcbpy）（OH2）]（RuOH2）也被质子化为[Ru（C8Otpy）（dcbpy）（OH）]-（RuOH）。电解液的pH值5.9。RuOH / meso-ITO电极的循环伏安图（CV）在pH为5-12的E1 / 2 = 0.80 V相对于Ag / AgCl时，显示出pH无关的氧化还原响应，被分配为非质子- RuIIOH / RuIIIOH的1e-氧化还原偶联过程。RuOH / meso-ITO电极相对于Ag / AgCl介于0.2和1.5 V之间的MPSCCS测量表明，在初始阶段，RuIV物质（暂定为RuIVO）以电催化的稳定状态存在。这表明在所采用的条件下，从RuIVO到RuVO的电化学氧化可与水亲核攻击竞争参与速率确定步骤的OO键形成。通过在RuVO的形成电势之前在1.4 V的低施加电势下进行电催化水氧化，暗示了对RuIVO的水亲核攻击也可能与RuIVO电化学氧化为RuVO竞争的可能性。在1.4 V下持续1 h的MPSCCS测量表明，RuOH在电极上逐渐转变为另一种催化剂（最可能是RuOx纳米颗粒）。