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Title: | 二維材料與矽之異質接面於提升光電化學產氧效率之應用 Enhanced Photoelectrochemical Efficiency by 2D Material-Silicon Heterojunction for Oxygen Evolution Reaction |
Authors: | Zhe-Yu Lee 李哲裕 |
Advisor: | 陳俊維(Chun-Wei Chen) |
Keyword: | 光電化學,水分解,產氧反應,石墨烯,二硫化鉬,蕭基接面, Photoelectrochemical(PEC),Water splitting,Oxygen evolution reaction(OER),Graphene,MoS2,Schottky junction, |
Publication Year : | 2019 |
Degree: | 碩士 |
Abstract: | 能源危機及急遽成長的能源需求迫使人類尋求替代能源來取代目前主要依賴的化石燃料,在近幾年發展的新能源中,結合電化學水分解及太陽能的光電化學水分解可直接將太陽能轉換為容易儲存之化學能,具有可再生性、對環境無害以及永續利用的特性,使其成為極具潛力的新興能源並吸引許多科學家投入研究。另一方面,自從2004年首次發現單原子層石墨烯之存在後,其特殊的物理及化學性質,二維材料成為近十年最熱門的研究材料之一,因此,本研究將首次利用二維材料結合矽基板於光電化學水分解之光陽極,致力於提升產氧之效率。
在此研究中,分為石墨烯及二硫化鉬兩種二維材料和矽基板形成之異質接面在光電化學水分解產氧的效率表現。第一部分為Si-Gr-Ni光陽極,利用傳統PMMA石墨烯轉印法將化學氣相沈積法成長之石墨烯轉印於n-type矽基板上,於介面形成石墨烯與矽之蕭基接面,再利用熱蒸鍍法將鎳金屬薄膜沈積於石墨烯表面。與Si-Ni 結構比較,從線性掃描伏安法(LSV)可觀察Si-Gr-Ni結構的效率提升,並從電化學阻抗分析(EIS)結果中證明了載子轉移電阻的降低。為了更加提升效率,利用鉑金屬奈米粒子參雜得到p-type石墨烯,p-type 石墨烯與n-type矽基板形成能障較大之蕭基接面,可有效降低載子覆合機率,從線性掃描伏安法(LSV)可觀察到明顯的效率提升,並且利用Mott-Schottky plot觀察到較強的內建電場。 第二部分則利用二硫化鉬與n-type矽之異質接面於產氧的效率提升,因其特殊的能帶彎曲,Si-MoS_2-Ni光陽極具有極佳的產氧效率,並且從線性掃描伏安法(LSV)中可觀察到兩種載子傳遞路徑,與能帶彎曲的結果一致,二硫化鉬的載子覆合機率也因此能帶彎曲結構被抑制,從PL與TRPL的結果可得到證實。 本實驗展示了二維材料與矽之異質接面於光電化學水分解效率提升之可行性,此外,石墨烯與二硫化鉬尚有許多改質的方法可調控其物理性質,如功函數、費米能階及導電性等,因此其未來發展值得期待。 Developing the alternative energy is imperative due to the energy crisis and exponential growth of energy demand in the decades. Among new energy sources, photoelectrochemical (PEC) water splitting into hydrogen and oxygen, which is renewable, environment-friendly, and sustainable, has been seen as one of the most promising way to solve the challenge. In addition, two dimensional materials also attract a lot of attention of scientists all over the world due to their peculiar physical properties since the first discovery of mechanically exfoliated graphene in 2004. In this study, application of 2D material-silicon heterojunction has been first time applied to the PEC water splitting for oxygen evolution reaction. Herein, 2D materials, graphene and MoS_2, coupled with n-type silicon have been used as water splitting photoanode for oxygen evolution reaction (OER). In the first part, graphene-silicon Schottky junction photoanode is synthesized by conventional PMMA graphene transfer method and thermal evaporation of nickel thin film. Compared to the Si-Ni structure, the Si-Gr-Ni photoanode shows enhanced OER efficiency from linear sweep voltammetry (LSV) measurement and reduced charge transfer resistance from electrochemical impedance microscopy(EIS). To further improve it, metallic p-type doping is adopted to tune the work function of graphene and the enhanced built-in potential is demonstrated by the Mott-Schottky plot. In the second part, Si-MoS_2-Ni photoanode is synthesized also by PMMA transfer method and thermal evaporation. Due to the special band bending in the photoanode, two carrier transporting paths have been observed from the LSV measurement and the reduced charge recombination of MoS_2-Si heterojunction, compared to pure MoS_2, has been proved by quenching of PL and longer life time of TRPL. Most importantly, the OER efficiency of Si-MoS_2-Ni photoanode is comparable to those in the literatures. In brief, the application of graphene and MoS_2 in this study has provided a 2D material-silicon heterojunction paradigm for PEC water splitting photoanode. Many modification strategies are worth expecting to optimize the efficiency. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/73130 |
DOI: | 10.6342/NTU201901106 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 材料科學與工程學系 |
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