Photoelectrochemical Activity of TiO2/MWCNT Thin-Film Electrodes with Different Film Structures Prepared by Combining Electrophoretic Deposition and Sol–Gel Method (Supporting Information)

Photoelectrodes have attracted significant attention in green hydrogen production via water electrolysis. Among others, titanium oxide (TiO2) is a representative photoelectrode for the conversion of solar energy in the ultravisible region into electrical and chemical energies. However, the poor solar adsorption of this material and the low anode reaction rate have limited the efficiency of hydrogen production via water electrolysis. In addition, there is an urgent need for more ecofriendly hydrogen production systems. The composite films of TiO2 and electronically conductive materials with various structures have been investigated to improve the photoelectrochemical activity of TiO2 by increasing the effective surface area of TiO2 and electronic conductivity of the films, which suppress the electron–hole pair combination. Herein, TiO2 and multiwalled carbon nanotube (MWCNT) composite films with various structures are prepared using the sol–gel method and electrophoretic deposition simultaneously, i.e., sol–gel electrophoresis deposition, under different solution conditions. Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) results reveals that additives and the mixing ratio of TiO2 sol and MWCNT dispersion solution in the electrophoresis bath affect film structure. Thin-film electrodes with different structures show different photoelectrochemical activities. Most as-fabricated TiO2/MWCNT composite thin-film electrodes outperform pristine TiO2 thin-film electrodes. TiO2 deposition on the MWCNT network surface with an antenna-like shape yields the best photoelectrochemical activity, achieving a low film resistance and ∼80 % anatase/rutile ratio.

光电极在绿色氢气生产的水电解过程中引起了广泛关注。其中，二氧化钛（TiO2）作为一种典型的光电极，能够将紫外光区域内的太阳能转化为电能和化学能。然而，该材料对太阳能的吸附性能较差，以及阳极反应速率较低，限制了通过水电解生产氢气的效率。此外，对更环保的氢气生产系统有着迫切的需求。通过增加二氧化钛的有效表面积和薄膜的电子导电性，以抑制电子-空穴对的复合，研究者们已对二氧化钛与具有各种结构的导电材料的复合薄膜进行了研究。本实验采用溶胶-凝胶法与电泳沉积法同步制备了具有不同结构的二氧化钛（TiO2）与多壁碳纳米管（MWCNT）复合薄膜，即溶胶-凝胶电泳沉积法，在不同溶液条件下进行。扫描电子显微镜（SEM）/能谱仪（EDS）结果显示，电解槽中的添加剂以及二氧化钛溶胶与碳纳米管分散溶液的混合比例会影响薄膜的结构。具有不同结构的薄膜电极表现出不同的光电化学活性。大多数制备的二氧化钛/碳纳米管复合薄膜电极的性能优于纯二氧化钛薄膜电极。在具有天线状形状的碳纳米管网络表面沉积的二氧化钛，因其优异的光电化学活性，实现了低薄膜电阻和约80%的锐钛矿/金红石比例。