現今科技產品有走向輕、薄、短、小之趨勢，讓人類對微小化材料產生迫切需求，由於奈米材料有很多化學及物理性質隨著粒徑變小而發生變化，奈米粒子雖具有高表面活性，卻容易產生聚集。由於介孔材料具有高比表面積之優勢，可改變材料表面特性，進而增加材料應用價值。本研究以三嵌段共聚物界面活性劑作為奈米介孔模板，溶膠-凝膠法輔以微胞理論合成具有高比表面積、蟲洞狀之介孔氧化鎢粉末，結合陽極氧化鋁模板技術，製備蟲洞狀介孔氧化鎢奈米纖維。
實驗結果顯示，以溶膠-凝膠法輔以三嵌段共聚物界面活性劑為奈米模板，可合成具有高比表面積(156 m2/g)之奈米介孔氧化鎢。三嵌段共聚物界面活性劑在煆燒溫度250 ℃前已移除，合成之介孔呈現具不規則之蟲洞狀結構。以三嵌段共聚物界面活性劑P123、L62所合成之蟲洞狀介孔氧化鎢粉末，其平均孔徑分別為9.8與4.9 nm。加入鹽酸溶液可形成穩定三嵌段共聚物界面活性劑之氫鍵結，強化介孔結構穩定，形成高比表面積、孔徑大小均一之蟲洞狀介孔氧化鎢。若添加量超過20 wt%去離子水及氫氧化鈉溶液則會減弱共聚物界面活性劑之氫鍵結，使比表面積下降。以無水酒精為溶劑、煆燒溫度為250 ℃之蟲洞狀介孔氧化鎢，晶粒外緣呈現直交之立方晶結構，隨煆燒溫度提高，氧化鎢結晶性、晶粒尺寸與蟲狀孔徑皆隨之成長，而使蟲洞狀介孔結構逐漸崩解，比表面積與孔洞體積下降；又因蟲洞狀孔洞仍存留於長大之晶粒內，阻礙氧化鎢晶粒成長，提高孔洞崩解溫度與熱穩定性。
蟲洞狀介孔氧化鎢之光致色變效應顯著並具再現性。氧化鎢奈米粒子大小為50 ~ 80 nm，對應之能隙值範圍為3.59~ 3.77 eV，與粒徑變化趨勢相近；蟲洞狀介孔氧化鎢能隙值為3.73 eV，比文獻報導塊材之能隙值大，顯現量子尺寸效應使氧化鎢能帶變寬。此外，本研究製作之奈米介孔氧化鎢氣體感測器有良好的回復性，由於NO氣體之脫附反應隨溫度升高而加速，於40與90 ℃對20 ppm之NO氣體之靈敏度分別達5.5與25。
以溶膠凝膠法製備浸鍍液，分別經浸鍍法、抽氣浸鍍法或充氣浸鍍法輔以氧化鋁模板皆可製備奈米介孔氧化鎢纖維。浸鍍法與抽氣浸鍍法所合成之奈米介孔氧化鎢纖維長度受限於浸鍍液流動性及凝結速率，纖維邊緣不平直。充氣浸鍍法則可改進上述缺失，藉由壓力50 psi之氮氣迫使浸鍍液完全填入AAM模板孔道內，可製備高準直之一維蟲洞狀介孔氧化鎢纖維，具有快速合成、簡化製程之優勢。
以充氣浸鍍法合成蟲洞狀介孔氧化鎢奈米纖維，其場發射行為受到基材、纖維直徑與孔洞分率之影響。蟲洞狀介孔氧化鎢奈米纖維於雙面膠/矽晶板基材上顯現團簇聚集現象，相較於銅膠帶/矽晶板基材上分散性有明顯差異，其起始電場比雙面膠/矽晶板基材為低，顯示蟲洞狀介孔氧化鎢奈米纖維於雙面膠/矽晶板基材上易發生屏蔽效應而提高起始電場與功函數。觀察纖維形態發現蟲洞狀介孔氧化鎢奈米纖維隨直徑愈大，孔洞比例下降，起始電場上升。由於無介孔之氧化鎢纖維並無場發射特性，電子發射應係藉由蟲洞狀介孔之結構作為氧化鎢奈米纖維場發射位置，氧化鎢奈米纖維之蟲狀孔洞愈多，局部功函數下降處愈多，使得起始電場下降，進而提升場發射特性。直徑20 nm之奈米介孔氧化鎢纖維於低外加電場(0.67 V/μm)有良好及穩定之場發射電流密度約1400 μA/cm2。量測時間超過20 h，未見明顯之電流密度衰減，大致仍保持初始電流密度，作為場發射顯示器電子源深具潛力。

The scientific and technological products move towards the slight, thin, short, small items now, the human being require the active demand for the minimized products. Many chemical and physical characterizations of nanomaterials differ from that of bulk materials with various particle sizes. Nanoparticles have the high surface activity, which easily agglomerated at the higher temperature. Mesoporous materials with high specific surface area, the surface characteristics and the values of applications can be promoted. Mesoporous tungsten oxide was prepared by the sol-gel method which the triblock copolymer formed micelles in the solution. Wormhole-like mesoporous tungsten oxide nanowires can be successfully prepared by the template-assisted technology.
Mesoporous tungsten oxide synthesized by triblock copolymer of L62 and P123 exhibits a Brunauer-Emmett-Teller (BET) surface area of 156 and 138 m2/g and wormhole-like mesopores with 4.9 an 9.8 nm, respectively. Triblock copolymer was completely removed at 250 ℃. For different additive conditions, HCl would further promote the BET surface area of mesoporous tungsten oxide than an additive of NaOH or above 20 % of distilled deionized water (H2O), which can be attributed to the stabilization of the micellization by hydrogen bonding among triblock copolymers. We also first find the vertical grain with cubic phase when it is calcined at 250 ℃. Tungsten oxide forms the orthorhombic phase with increasing the calcined temperature. Increasing the calcination temperature encourages the growth of tungsten oxide crystallites with a loss of mesoporous surface area, but the presence of the wormhole-like mesopores can be an obstacle for the grain growth of tungsten oxide. The wormhole-like mesostructure can retard the collapse rate of mesopores through grain growth during crystallization.
The wormhole-like mesoporous tungsten oxide exhibits outstanding sensitivity and reproduction in photochromic properties. The indirect EG for the initial state is estimated from 3.59 to 3.77 eV, in accord with the average sizes of tungsten oxide nanoparticles about 50 to 80 nm. This may be due to a relationship between nanoparticle size and the optical band gap of tungsten oxide. Mesoporous tungsten oxide powder synthesized by triblock copolymer exhibits a high transmittance with an indirect EG of 3.73 eV due to the quantum size effects. Gas sensing measurement reveals excellent recovery and sensitivity under the low gas concentration for mesoporous tungsten oxide film and sensitivities of 5.5 and 25 as exposed to 20 ppm NO gas at 40 and 90 ℃, respectively.
Wormhole-like mesoporous tungsten oxide nanowires can be successfully prepared by the immersion and gas-extracted or gas-filled methods. In the immersion and gas-extracted methods, the lengths of wormhole-like mesoporous tungsten oxide nanowires with rough surface are limited by the capillary attraction and the condensation rate of the immersed solution. The results performed that the gas-filled method has a higher efficiency to induce mesoporous materials into membrane channels with fast or simple processes.
The field-emission properties of wormhole-like mesoporous tungsten oxide nanowires prepared by gas-filled method are affected by the substrate, width sizes, and the percentage of mesopores volume within nanowires. The turn-on field of mesoporous tungsten oxide nanowires increases and which results screening effect of the lower current density on the double-stick/Si substrate. Mesoporous tungsten oxide nanowires on the Cu-tape/Si substrate improved these disadvantages reveal the low turn-on field with increasing the percentage of mesopores volume. The work function is dramatically reduced near mesopores of tungsten oxide nanowires. In this study, the surface structure of tungsten oxide nanowires may have a high density of mesopores, which serve as the emitting centers. The average diameter of 20 nm for mesoporous tungsten oxide nanowires on the Cu-tape/Si substrate reveals the low turn-on field of 0.67 V/μm with stable current density of about 1400 μA/cm2 for 20 h, which is no significant degradation. This makes wormhole-like mesoporous tungsten oxide nanowires a suitable alternative candidate for field-emission emitters.

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