還原氧化石墨烯奈米複合材料之製備與化學偵測
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2021
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為因應目前感測器低成本、微小化、便於攜帶、穿戴式以及可即時監控的發展趨勢，本研究開發一系列簡易且低成本之方式合成還原氧化石墨烯 (reduced graphene oxide, RGO) 為主體的奈米複合材料，在氧化石墨烯結合有機或無機材料並與觸媒奈米粒子綴合的反應過程中，同時將其進行還原，以一步化合成多元還原氧化石墨烯奈米複合材料，並探討這些複合材料於感測方面之相關應用。
依所合成之石墨烯複合材料以及分析物的不同，研究之內容可分為三大部份，第一為應用石墨烯所具有的電催化特性以及表面高活性位點，製備為可同時檢測苯二酚同分異構物之電化學感測器，第二及第三部分則是透過石墨烯本身的高機械強度以及高導電性，發展為可撓性濕度感測元件以及高靈敏性的NH3感測元件。
第一部分的實驗設計是利用多元醇法 (polyol synthesis) 結合有機金屬裂解法 (Metal Organic Decomposition, MOD)，以簡易且低成本的方式一步化合成金奈米粒子/還原型氧化石墨烯/三氧化鎢 (AuNPs/RGO/WO3) 三元奈米複合材料，並將此材料製備為AuNPs/RGO/WO/GCE電化學感測元件，提供了能有效區別並快速檢測hydroquinone (HQ) 以及catechol (CC) 混合樣品之感測平台。材料中RGO與AuNPs的高導電性與電催化活性，能顯著提升以Cyclic Voltammetry (CV)和Differential Pulse Voltammetry (DPV) 檢測HQ以及CC之靈敏度與選擇性，且提供新的電子傳導途徑，有效地改變材料中電子之傳遞能力，進一步增進元件的感測特性，而在真實環境下檢測HQ和CC，此元件依然具備良好的定性與定量之能力，其RSD分別為85%~111%和89%~119%，證實開發此感測材料對於HQ以及CC之實際檢測具有一定的應用價值。
而實驗第二部分為利用高分子單體化學氧化聚合為導電高分子而同時進行還原作用的方式，設計出Pt/polythiophene/RGO阻抗式濕度感測元件，此感測元件以RGO和polythiophene所具有高比表面積、高導電性以及Pt粒子所提供的電子傳導路徑等性質，將有效提高對於濕度之感測特性，此外藉由RGO具有高機械強度以及高可撓之特性，所製備之感測元件可撓性極佳，對於發展為穿戴式感測材料有極大之潛力。
第三部分為以簡易且一步化之方式合成Au/polythiophene/RGO、Ag/polythiophene/RGO、Pd/polythiophene/RGO以及Pt/polythiophene/RGO奈米複合材料並應用於NH3氣體之檢測，探討不同金屬觸媒前驅物對於材料整體合成之影響，並分析這些奈米複合材料對NH3感測之差異性，由特性分析結果可知， Au/polythiophene/RGO及Ag/polythiophene/RGO奈米複合材料，觸媒還原比率以及polythiophene聚合程度皆較高，因此具有較低的電阻值，而因觸媒的催化能力以及π-πstacking電荷載子快速傳遞的效應，Au/polythiophene/RGO以及Ag/polythiophene/RGO感測元件對NH3氣體也具有較為優異的感測特性，對NH3氣體有極快的反應速度並可適用低濃度 (200 ppb) 之檢測，如若有類似第二部分元件之可撓性，於氣體之檢測應用上便具有極大的發展潛力。
This dissertation proposes a series of simple and low-cost routes to efficiently synthesize reduced graphene oxide (RGO)-based nanocomposite materials along with the inexorable developments of cost-effective, miniaturized, portable, wearable and real-time monitoring of sensors. Graphene oxide reacted with organic or inorganic materials and combined with various nanoparticles to synthesize nanocomposite materials by one-pot methods in which the electrons was provided to reduce simultaneously the graphene oxide. The sensing-related applications of the nanocomposite materials based RGO was discussed more fully in this research. According to the differentfabrication of nanocomposite materials or detection of analytes, the content of this discuss was divided into four themes. First, through strong electrocatalytic activity and abundant active binding sites on the surface of RGO, a highly selectivity electrochemical sensor for simultaneously quantifying benzenediol isomers was successfully fabricated. Subsequently, the growth of the extremely flexible humidity sensor and the highly sensitive NH3 sensor based on RGO nanocomposite materials, attributing to strong mechanical strength and high conductivity of graphene. Finally, the hydrophilicity of the functional groups on graphene oxide is used to improve the humidity sensing characteristics of lanthanide oxides. First, the experimental design employed the polyol method combined with Metal Organic Decomposition (MOD) with the features of simple and low-cost to synthesize gold nanoparticles/reduced graphene oxide/tungsten oxide (AuNPs/RGO/WO3) ternary nanocomposite material, which as the sensing material and was coated on a glass carbon elerton to fabricate the AuNPs/RGO/WO3/GCE electrochemical sensor. The sensor can used as a sensing platform, revealing the ability of quickly detected and effectively distinguished the mixed samples containing hydroquinone (HQ) and catechol (CC). For the detection of HQ and CC, the RGO and AuNPs not only supplied high conductivity and powerful electrocatalytic activity to significantly enhanced the sensitivity and selectivity but also provided the new electronic conduction paths to obviously ameliorate the sensing capabilities of the AuNPs/RGO/WO3/GCE electrochemical sensor. In addition, the electrochemical sensor still maintained excellent qualitative and quantitative analysis for the detection of HQ and CC in the presence of river water. As a result, the detection of HQ and CC in real environment successfully stride forward by the development of AuNPs/RGO/WO3 nanocomposite material. In the second experiment, a facile and low cost one-pot method was applied in the synthesis of Pt/polythiophene/RGO nanocomposite material to produce the impedance humidity sensor. 2-thiophene methanol (2-TPM) reacted with PtCl42 ions via oxidative polymerization process and released electrons to simultaneously reduce PtCl42 ions and GO to Pt nanoparticles and RGO, respectively, affording high conductivity and large specific surface area by RGO and polythiophenethe, as well as conduction pathways by Pt nanoparticles, effectively improved the electrical and humidity-sensing performance of the humidity sensor. Furthermore, a polyethylene terephthalate (PET) substrate have been modified by the Pt/polythiophene/RGO nanocomposite, forming a humidity sensor with remarkable flexiblity due to the the intrinsic mechanical strength and flexibility of RGO. This results also demonstrated that the Pt/polythiophene/RGO nanocomposite material possess significant potential for the development of wearable sensors. The third part is to synthesize Au/polythiophene/RGO, Ag/polythiophene/RGO, Pd/polythiophene/RGO and Pt/polythiophene/RGO nanocomposites materials by using a simple one-step method and these nanocomposites materials were employed as sensing films for detecting the NH3 gas in the experiment. The influence of the catalyst precursor on the synthesis of these nanocomposites materials were investigated. The results presented that Au/polythiophene/RGO and Ag/polythiophene/RGO nanocomposites materials prossess lower resistance due to the catalyst precursor has a higher ratio of reduction and the polythiophene has a great degree of polymerization. However, the catalytic of metal catalysts surface and the rapid transfer of charge carriers by π-π stacking greatly contribute to the Au/polythiophene/RGO and Ag/polythiophene/RGO sensors possess excellent sesing performance on NH3 gas. The sensors have superior response time and can used for the detection of low concentration NH3 gas (200 ppb) . The sensors will have greater development potential if it can flexibility.
This dissertation proposes a series of simple and low-cost routes to efficiently synthesize reduced graphene oxide (RGO)-based nanocomposite materials along with the inexorable developments of cost-effective, miniaturized, portable, wearable and real-time monitoring of sensors. Graphene oxide reacted with organic or inorganic materials and combined with various nanoparticles to synthesize nanocomposite materials by one-pot methods in which the electrons was provided to reduce simultaneously the graphene oxide. The sensing-related applications of the nanocomposite materials based RGO was discussed more fully in this research. According to the differentfabrication of nanocomposite materials or detection of analytes, the content of this discuss was divided into four themes. First, through strong electrocatalytic activity and abundant active binding sites on the surface of RGO, a highly selectivity electrochemical sensor for simultaneously quantifying benzenediol isomers was successfully fabricated. Subsequently, the growth of the extremely flexible humidity sensor and the highly sensitive NH3 sensor based on RGO nanocomposite materials, attributing to strong mechanical strength and high conductivity of graphene. Finally, the hydrophilicity of the functional groups on graphene oxide is used to improve the humidity sensing characteristics of lanthanide oxides. First, the experimental design employed the polyol method combined with Metal Organic Decomposition (MOD) with the features of simple and low-cost to synthesize gold nanoparticles/reduced graphene oxide/tungsten oxide (AuNPs/RGO/WO3) ternary nanocomposite material, which as the sensing material and was coated on a glass carbon elerton to fabricate the AuNPs/RGO/WO3/GCE electrochemical sensor. The sensor can used as a sensing platform, revealing the ability of quickly detected and effectively distinguished the mixed samples containing hydroquinone (HQ) and catechol (CC). For the detection of HQ and CC, the RGO and AuNPs not only supplied high conductivity and powerful electrocatalytic activity to significantly enhanced the sensitivity and selectivity but also provided the new electronic conduction paths to obviously ameliorate the sensing capabilities of the AuNPs/RGO/WO3/GCE electrochemical sensor. In addition, the electrochemical sensor still maintained excellent qualitative and quantitative analysis for the detection of HQ and CC in the presence of river water. As a result, the detection of HQ and CC in real environment successfully stride forward by the development of AuNPs/RGO/WO3 nanocomposite material. In the second experiment, a facile and low cost one-pot method was applied in the synthesis of Pt/polythiophene/RGO nanocomposite material to produce the impedance humidity sensor. 2-thiophene methanol (2-TPM) reacted with PtCl42 ions via oxidative polymerization process and released electrons to simultaneously reduce PtCl42 ions and GO to Pt nanoparticles and RGO, respectively, affording high conductivity and large specific surface area by RGO and polythiophenethe, as well as conduction pathways by Pt nanoparticles, effectively improved the electrical and humidity-sensing performance of the humidity sensor. Furthermore, a polyethylene terephthalate (PET) substrate have been modified by the Pt/polythiophene/RGO nanocomposite, forming a humidity sensor with remarkable flexiblity due to the the intrinsic mechanical strength and flexibility of RGO. This results also demonstrated that the Pt/polythiophene/RGO nanocomposite material possess significant potential for the development of wearable sensors. The third part is to synthesize Au/polythiophene/RGO, Ag/polythiophene/RGO, Pd/polythiophene/RGO and Pt/polythiophene/RGO nanocomposites materials by using a simple one-step method and these nanocomposites materials were employed as sensing films for detecting the NH3 gas in the experiment. The influence of the catalyst precursor on the synthesis of these nanocomposites materials were investigated. The results presented that Au/polythiophene/RGO and Ag/polythiophene/RGO nanocomposites materials prossess lower resistance due to the catalyst precursor has a higher ratio of reduction and the polythiophene has a great degree of polymerization. However, the catalytic of metal catalysts surface and the rapid transfer of charge carriers by π-π stacking greatly contribute to the Au/polythiophene/RGO and Ag/polythiophene/RGO sensors possess excellent sesing performance on NH3 gas. The sensors have superior response time and can used for the detection of low concentration NH3 gas (200 ppb) . The sensors will have greater development potential if it can flexibility.
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氧化石墨烯, 石墨烯複合材料, 奈米粒子, 一步合成, 氣體感測, 電化學感測, 濕度感測, Graphene, Graphene composite materials, Nanoparticles, One-step synthesis, Gas sensing, Electrochemical sensing, Humidity sensing