鎳摻雜及氫化之二氧化鈦奈米管對光裂解水之影響

Abstract

當前綠色能源受到人類重視，固態氧化物燃料電池(SOFC)、質子交換膜燃料電池(PEM) 廣泛被應用。上述電池所需燃料皆以氫氣做為主軸，產氫系列研究極受到重視，其中太陽光電化學電池最具有發展潛力，電池內陰極二氧化鈦奈米管將有助於分解水產氫，因此二氧化鈦奈米管的研究將成為重點。 本研究利用陽極處理法製備TiO2 奈米管，分別使用摻雜鎳、氫化及電化學還原等改質方法，並以 SEM/EDS 觀察其形貌、X-ray 分析相結構及XPS 分析表面化學鍵結，而後在太陽光模擬器(Solar Simulator AM 1.5) 照射下使用水裂解效率量測系統。 在效率測量中發現，以300°C 進行氫化將氫擴散進二氧化鈦奈米管晶格內，產生Ti-OH 鍵結增加氧空缺數量，並提高光裂解水的效率。電化學還原在二氧化鈦奈米管表面將Ti4+ 還原成Ti3+ 而產生氧空缺，可提高光裂解水的效率，將電化學還原完的試片退火後再氫化處理，效率會再次提高。 摻雜鎳的處理中，利用浸泡法，浸泡0.01M 醋酸鎳10 分鐘的經氫化後，於0.1M 氫氧化鉀中進行光裂解水測試達到最大效率值0.452%，較未反應的二氧化鈦提高了4.5 倍；使用陽極處理法，在添加0.2wt% 醋酸鎳電解液中進行陽極處理製備二氧化鈦奈米管經氫化後，於0.1M 氫氧化鉀中進行光裂解水測試可達到最大效率值0.476%，較未反應的二氧化鈦提高了4.7 倍。經上述兩種摻雜鎳的處理方法得知，摻雜鎳的二氧化鈦奈米管經氫化處理後可大幅增加光電流密度。

The solid oxide fuel cell (SOFC) and proton exchange membrane fuel cell (PEM) with hydrogen as a fuel are presently widely used. The studies on hydrogen production technologies are thus very important now. Among the hydrogen producing technologies, the photoelectrochemical cell (PEC) has a great potential to become the best choice. For PEC electrodes, TiO2 NTs, are useful for water splitting, so we focus on the study of TiO2 NT electrode fabrication. We employ the anodization method to produce TiO2 NTs, and use doping, and hydrogenation to improve their efficiency. The modified TiO2 NTs have been characterized with SEM, EDS, XPS and XRD. In the last step of our study, we irradiate the samples to measure the efficiency of water splitting with solar simulator. Based on our analysis, we find that at 300°C hydrogen can diffuse into the TiO2 lattice and generate the Ti-OH bonding to increase the oxygen vacancies, and thus enhances the efficiency of water splitting. In addition, electrochemical reduction TiO2 NTs can also reduce Ti4+ to Ti3+ on the surface to generate oxygen vacancies, and the vacancies can improve the efficiency of water splitting. We can also improve water splitting efficiency by Ni-doping of TiO2 to catalyze and enhance the TiO2 hydrogenation process with two different methods. First, with the soaking method, samples can achieve 0.452% efficiency for hydrogen production, which is 4.5 times higher than that of untreated TiO2 nanotubes. Second, with the anodization method, the efficiency increases to 0.476%, which is 4.7 times higher than that of untreated TiO2 nanotubes.