【作者】 杨洁；

【导师】 于涛；

【作者基本信息】 南京大学 ， 物理学， 2016， 博士

【摘要】 在各种电化学系统中,电子能否有效传输是决定系统性能的一个重要因素。掺锡氧化铟(Sn:In2O3,1T0)材料由于具有较高的导电性被广泛应用在各种电化学系统以及光电器件中。电化学系统的工作过程通常伴随着电极与电解液的反应,电极与电解液的表面接触面积越大,电极与电解液的反应位点越多,系统性能越好。商用的平面ITO导电电极虽然具有高导电能力,但与电解液的表面接触面积较小,可担载的活性物质的量也较少,对提高系统性能不利。ITO纳米线阵列相较于平面ITO电极拥有较大的表面面积,在不影响电极导电性的同时提高了可担载活性物质的量,较合适应用在电化学系统中。我们用化学气相沉积法(Chemical vapor deposition,简称CVD)制备了ITO纳米线阵列,这种ITO纳米线阵列兼具导电性高,与电解液的表面接触面积大等优点,将ITO纳米线阵列引入到光电化学分解水、超级电容器中,试图利用ITO的这些性质提高电化学系统的活性物质担载量和电子传输能力,进而提高系统的性能。本文包括以下内容：1、将ITO纳米线阵列引入到光电化学分解水系统的光阳极中,先用CVD法在石英片上生长ITO纳米线阵列,再用化学水浴法在ITO纳米线阵列上均匀包裹一层致密的α-Fe2O3纳米颗粒,构成了一个核壳结构,我们测试了这个核壳结构的光阳极在AM1.5模拟太阳光照下的光电流密度。制备的核壳结构电极在相对于氢电位1.23 V的电压下,产生的光电流密度为1.1 mA/cm2。这个性能比平面ITO结构的光阳极高一倍左右。我们用光吸收谱表征了核壳结构光阳极和平面α-Fe2O3光阳极的光吸收情况,优化过的核壳结构光阳极比平面结构的α-Fe2O3光阳极具有更高的可见光吸收效率。2、我们用电化学阻抗谱法测试核壳结构的光阳极内部电阻情况,实验结果表明核壳结构的光阳极内部的电阻比报道的很多光阳极小,充分说明ITO纳米线的引入提升电极的电子传输能力。3、将ITO纳米线阵列引入到超级电容器中,用化学气相沉积的方法在碳布上沉积ITO纳米线阵列,形成了一个类似毛刷的核壳结构导电骨架,在导电骨架上电化学沉积赝电容活性物质Ni3S2,制备的电极比没有ITO的电极质量比电容高一倍左右。由于沉积有ITO纳米线阵列的电极相对于平面结构电极表面积大,Ni3S2的担载量增大,电极的面积比电容也得到了提升,最高可以达到3.87 F/cm2,比平面电极有将近两倍的提升。电极的倍率性能也得到了提升。4、我们将拥有高面积比电容的电极组装成一个对称型的全固态超级电容器,器件的面积比电容达到0.74 F/cm2。在39.9 W/cm3的功率密度下器件的能量密度为1.02 mWh/cm3,当功率密度增加到399.9 mW/cm3时,器件可输出的能量密度仍能保持0.56mWh/cm3,表现出很好的倍率性能。除此之外。该器件在1.5 cm的曲率半径下弯折后测得的电容性能仍能保持未弯曲时的90%,说明我们做的电极在柔性器件方面很有潜力。本论文的研究工作为电化学系统提供了一种具有高导电性和高表面面积的电极,有望在光电化学分解水和超级电容器等系统中解决一些活性物质电荷传输能力较差的问题。更多还原

【Abstract】 Efficient electron transfer was an important factor for obtaining high-performance electrochemical systems. The most common electrode for electron transfer and collection was ITO electrode. Surface contact area of the electrode with the electrolyte in the electrochemical systems decides the reaction sites of the electrodes and the electrolyte, which plays a crucial rule in the performance of the systems. However, the commercial ITO electrode possesses low surface area, which can only load very few active materials and restricts the performance of the electrochemical systems. ITO nanowire arrays, a kind of conductive metal doped metal oxide are considered as promising electrodes in the electrochemical systems for their good conductivity and high surface area. Herein, we introduced the conductive ITO nanowire arrays in various electrochemical systems such as photoelectrochemical water splitting and supercapacitors. We tried to improve their performances in the aspects of improving the loading massage of the active materials and the electrons transfer efficiency. The work was included as follows:1> We prepared ITO nanowire arrays using chemical vapor deposition method, and comapactly deposited α-Fe2O3 nanoparticles on the ITO nanowire arrays, which formed a core-shell structure (ITO@α-Fe2O3). The prepared optimized ITO@α-Fe2O3 electrode possessed higher absorption than planar α-Fe2O3 electrode, which was attibuted to the high surface area of the ITO@α-Fe2O3 electrode. The ITO@α-Fe2O3 electrode exhibited a high current density of 1.1 mA/cm2 at 1.23 V vs. RHE under AM 1.5 illumination. The value was twice higher than the planarα-Fe203 electrode.2> EIS curves was meatured to characterized the resistance in the ITO@α-Fe203 electrode and the interface between the ITO@α-Fe2O3 electrode and the electrolyte. Lower resistances in the ITO@α-Fe2O3 electrode and the interface were obtained for our prepared ITO@α-Fe2O3 electrode.3、ITO nanowire arrays were also introduced to the electrodes of supercapacitors. We electrodeposited Ni3S2 nanosheets on the chemical vapor deposited ITO nanowire arrays. The prepared electrodes exhibited a high specific capacitance of 1865 F/g, while the planar electrodes without ITO nanowire arrays displayed only about 800 F/g. We also obtained a high areal capacitance of 3.87 F/cm2. A good rate performance was also obtained when we introduced ITO nanowire arrays in the electrodes.4、The symmetric all-solid state flexible supercapacitors based on our prepared electrodes exhibited a high areal capacitance of 0.74 F/cm2, which was higher than many reported literatures. The flexible supercapacitor displayed an excellent energy density of 1.02 mWh/cm3 at 39.9 W/cm3, and can still maintain 0.56 mWh/cm3 at 399.9 mW/cm3. The capacitance can also maintain 90% when we bent the device at a radius of 1.5 cm, which demonstrate the potential application of our prepared electrodes in the flexible device.In this paper, ITO nanowire arrays were introduced to two electrochemical systems to improve the electron transfer and active materials loading in the systems. The strategy was considered as an effective way to improve the performance of electrochemical systems.更多还原