Nanostructured thin films are widely investigated for application in multifunctional devices thank to their peculiar optoelectronic properties. In this work anatase TiO2 nanoparticles (average diameter 10 nm) synthesized by a green aqueous sol-gel route are exploited to fabricate optically active electrodes for pseudocapacitive-electrochromic devices. In our approach, highly transparent and homogeneous thin films having a good electronic coupling between nanoparticles are prepared. These electrodes present a spongy-like nanostructure in which the dimension of native nanoparticles is preserved, resulting in a huge surface area. Cyclic voltammetry studies reveal that there are significant contributions to the total stored charge from both intercalation capacitance and pseudocapacitance, with a remarkable 50% of the total charge deriving from this second effect. Fast and reversible colouration occurs, with an optical modulation of ~60 % in the range of 315 - 1660 nm, and a colouration efficiency of 25.1 cm2/C at 550 nm. This combination of pseudocapacitance and electrochromism makes the sol-gel derived titania thin films promising candidates for multifunctional "smart windows".

中文翻译：

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溶胶-凝胶衍生的电致变色二氧化钛纳米结构中的赝电容行为

由于其独特的光电特性，纳米结构薄膜被广泛研究用于多功能器件。在这项工作中，通过绿色水溶胶-凝胶路线合成的锐钛矿 TiO2 纳米颗粒（平均直径 10 nm）被用于制造用于赝电容电致变色器件的光学活性电极。在我们的方法中，制备了在纳米颗粒之间具有良好电子耦合的高度透明和均匀的薄膜。这些电极呈现出海绵状的纳米结构，其中保留了天然纳米颗粒的尺寸，从而产生了巨大的表面积。循环伏安法研究表明，插层电容和赝电容对总存储电荷有重大贡献，来自第二个效应的总电荷的显着 50%。发生快速且可逆的着色，在 315 - 1660 nm 范围内具有约 60% 的光调制，在 550 nm 处的着色效率为 25.1 cm2/C。这种赝电容和电致变色的结合使得溶胶-凝胶衍生的二氧化钛薄膜有望成为多功能“智能窗”的候选者。