Solvent mixtures for improved electron transfer kinetics of titanium-doped polyoxovanadate-alkoxide clusters
Solvent mixtures for improved electron transfer kinetics of titanium-doped polyoxovanadate-alkoxide clusters
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DOI：
10.1039/d3ta01179h
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发表时间：
2023-06-02
影响因子：
11.9
通讯作者：
Matson，Ellen M.
中科院分区：
文献类型：
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作者：
Dagar，Mamta;Corr，Molly;Matson，Ellen M.
适用于电网规模应用的新兴的、可流动的电化学能量存储技术通常受到阻碍整体能量转换效率的缓慢的电子转移动力学的限制。为了提高我们对这些动力学限制的理解，在异金属电荷载体，我们研究了溶剂的作用，在影响异质电子转移的速率，证明其对动力学的二钛取代的多钒酸盐-醇盐簇，[Ti 2 V4 O 5（OMe）14]的影响。我们的研究还表明，一个电子的还原和氧化过程表现出不同的速率，表明不同的电子转移机制是有效的。我们报告，碳酸丙烯酯和乙腈的1：4 v/v混合物可以导致一个电子氧化的电子转移速率增加三倍，并且与纯乙腈相比，一个电子还原过程增加两倍。 我们将这种行为归因于溶剂-溶剂相互作用，导致偏离理想溶液行为。MeCN-PC混合物在20次充电/放电循环中的库仑效率保持在≥90%，高于单个溶剂获得的效率。这些结果提供了对溶剂在提高电荷转移速率中的作用的深入了解，并为系统地调整溶剂组合物以产生更快的电子转移动力学铺平了道路。
Emergent, flowable electrochemical energy storage technologies suitable for grid-scale applications are often limited by sluggish electron transfer kinetics that impede overall energy conversion efficiencies. To improve our understanding of these kinetic limitations in heterometallic charge carriers, we study the role of solvent in influencing the rates of heterogeneous electron transfer, demonstrating its impact on the kinetics of di-titanium substituted polyoxovanadate-alkoxide cluster, [Ti2V4O5(OMe)14]. Our studies also illustrate that the one electron reduction and oxidation processes exhibit characteristically different rates, suggesting that different mechanisms of electron transfer are operative. We report that a 1 : 4 v/v mixture of propylene carbonate and acetonitrile can lead to a three-fold increase in the rate of electron transfer for one electron oxidation, and a two-fold increase in the one electron reduction process as compared to pure acetonitrile. We attribute this behavior to solvent–solvent interactions that lead to a deviation from ideal solution behavior. Coulombic efficiencies ≥90% are maintained in MeCN–PC mixtures over 20 charge/discharge cycles, greater than the efficiencies that are obtained for individual solvents. The results provide insight into the role of solvent in improving the rate of charge transfer and paves a way to systematically tune solvent composition to yield faster electron transfer kinetics.