混合相二氧化鈦奈米柱陣列之合成、特性鑑定及其成長機制探討

Synthesis, Characterization, and Crystal Nucleation Pathway of Heterogeneous Phase TiO2 Nanorod Arrays

高立誠(Li Cheng Kao)

指導教授 ： 劉雅瑄

國立臺灣大學/理學院/地質科學研究所/博士(2017年)

https://doi.org/10.6342/NTU201702832

摘要

二氧化鈦因為其化學穩性佳，有著良好的光催化能力和對環境的友善性，近幾年來被廣泛的應用。其中材料合成的結晶形態上，因為混合相一維奈米結構擁有載子移動優良、光應用性佳和利於光電催化反應等特性，特別受關注。然而受限於二氧化鈦本身成長偏好的限制，傳統溶液相合成多以懸浮於溶液中的顆粒經離心、煅燒的方式取得材料，難以合成出垂直基材表面成長的大規模混相態二氧化鈦奈米柱陣列薄膜。在本研究中，利用基材濺鍍層與金紅石相二氧化鈦的結晶結構相似的概念，設計出雙面二氧化鈦奈米柱陣列電極，並在兩面分別沉積上性能相異的量子點達到大幅提升光分解水產氫的效率。再者，透過對溶液中二氧化鈦成長單體的認識，成功的利用固體前驅物有效地動態改變了溶液中酸度、鈦和氯離子濃度，營造一混和相二氧化鈦奈米柱陣列薄膜可成長之水溶液。最後，因為水溶液的成長環境其鈦前驅物水解結晶的速度相當快且難以控制，透過有機溶液為主的成長環境，達到以顆粒彼此聚合的成長方式來合成垂直成長於基材表面的混和相一維二氧化鈦奈米柱陣列薄膜，並透過同步輻射光源針對不同相聚合產生介面的缺陷分析。缺陷變化趨勢與光催化能力進步幅度一致說明了在成長異質同相的介面所產生的缺陷有助於材料光催化能力的增進。雖然晶體的成長過程相當複雜且依然還有許多部份是未知，但透過更基礎的方式去理解，可以設計出更適合特定應用的材料特性。

關鍵字

二氧化鈦 ； 能源材料 ； 光催化劑 ； 晶體成長 ； 加速器光源

並列摘要

Titanium dioxide (TiO2) has extensive technological applications because of its chemical stability, general reactivity, high photocatalytic activity, and nontoxicity. 1D-nanostructures arrays with heterogeneous phases which provided effective charge separation and collection and enhanced photocatalytic activity aroused wildly attention. Reports about the conventional solution-based method for synthesizing heterogeneous phase 1D TiO2 nanorod which is suspended in solution and obtained by centrifugation and sintering are hard to preserve as a large-scale film. Thus, geometrically 1D nanostructured arrays offer unique properties that are difficult to synthesize by conventional solution-based method. In this thesis, the double-sided CdS and CdSe co-sensitized 1D TiO2 photoelectrode was achieved due to epitaxial relation between the FTO substrate and rutile TiO2 with a small lattice mismatch, leading hight solar-to-hydrogen conversion efficiency. Besides, the TiO2 growth monomers in solution was well adjusted by adding the additional solid-state precursor, forming the anatase growth-friendly condition. At last, the nonaqueous approaches provides better control over reaction rates than that in aqueous dominant condition. The anatase/rutile heterogeneous TiO2 crystal structure in hierarchical architecture was implemented through forming the hybrid organic-inorganic interfaces in solvent-based environment. This specially shaped nanostructures with interface defects was achieved by introducing the oriented attachment growth mechanism, providing enhanced photocatalytic activity and remarkable crystalline phase stability. Although the nucleation and condensation process are still too complex to fully comprehend, understanding the growth mechanism will be a useful strategy for the artificial material synthesis.

並列關鍵字

titanium dioxide ； energy materials ； photocatalyst ； crystal nucleation ； synchrotron-based X-ray spectroscopy

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