功能性二氧化鈦-碳複合纖維應用於水中污染物之電催化降解

Functional TiO2 composite carbon fibers for electro-catalytic degradation of water pollutants

吳偵慈(Jhen-Cih Wu)

指導教授 ： 侯嘉洪

國立臺灣大學/工學院/環境工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201902299

摘要

近年來，隨著水與能源鏈結(Water-Energy Nexus)的觀念受到 重視，開發水與能源整合型處理系統為當今 的主要趨勢，電化學水處理系統 不僅可以光伏發電驅動且能有效去除水中污染物產生潔淨水。其中，電催化(Electrocatalysis) 被視為是具發展潜力的電化學水處理技術之一，可用於染料、藥物和個人保健用品(PPCPs)及水中新興汙染物之降解。 透過施加電壓，直接於陽極電極表面降解水中汙染物，或是透過產生 強氧化性之物種將污染物轉化為CO2、H2O及小分子。合適之陽極催化材料可以加速 產生強氧化活性物種及有利於提升整體降解效果，其中，將具催化效果之奈米顆粒(如TiO2、SnO2和Pt)與適當之載體結合，製備功能型電催化電極，受到各方的矚目。本研究透過 靜電紡絲技術(Electrospinning)製備之複合型TiO2碳纖維(TiO2/CF)，以碳化之靜電紡絲纖維作為高導電性之基材，不僅有利於提升電子轉移能力，同時將TiO2奈米顆粒有效分散於纖維上，亦可良好發揮TiO2之催化效果，以作為具高電催化活性之電極， 進一步探討其應用於電催化去除汙染物之可行性。透過掃描式電子顯微鏡(SEM)、X光繞射分析(XRD)和X射線光電子能譜(XPS)了解TiO2/CF的表面型態、晶體結構和化學狀態，電化學阻抗圖譜(EIS)評估在不同碳化溫度下之電極電阻，並以光漫反射光譜(DRS)進一步求得材料的能隙大小變化。研究結果指出TiO2濃度、碳化溫度及 施加電壓對於電催化效果有顯著的影響。隨著碳化溫度的增加，電極的導電性顯著提升有利於快速之電子轉移，而TiO2的主要晶體結構從原本的複合晶相轉變為金紅石相，與純TiO2粉末相比，TiO2/CF在1000度碳化後電極的能隙大幅下降(3.1 eV→2.39 eV)，推測可能是高導性之碳－鈦複合結構及金紅石相所致。為了進一步評估TiO2/CF之電催化活性，以結晶紫作為汙染物進行電催化實驗。實驗結果顯示，TiO2(1.2)/CF-1000在僅施加1 V的電壓下，即有85%的降解效果。因此，本研究製備之TiO2/CF電極展現優異的電催化活性，不僅提高污染物降解效果，又可降低電催化之能源需求。此外，本研究亦建立光伏驅動之電催化降解系統，透過將太陽能轉換成電能的方式，將更有利於電催化水處理技術之永續發展，展現高度應用潛力。

關鍵字

靜電紡絲 ； 二氧化鈦 ； 奈米複合材料 ； 電催化降解 ； 太陽能

並列摘要

Electrocatalysis is one of the promising electrochemical processes, which can degrade water pollutants such as dyes, personal care and pharmaceutical products (PPCPs) and other emerging contaminants into CO2 , H2O or biodegradable organic ones. The electrocatalytic performance is mainly determined by the anodic material, which governing the production of strong reactive oxygen species (‧OH and H2O2). TiO2 has many advantages, such as low cost, good chemical compatibility , long term stability. However, its low electrical conductivity may result in restrictions on the use of electrocatalyst. As the anodic material, TiO2 functional electrode can be produced by the integration of TiO2 nanoparticles with an appropriate support material.

The main objective of this study is to prepare a novel electrocatalytic electrode by decorating TiO2 nanoparticles onto electrospun carbon fibers(TiO2/CF) for degradation of water pollutants. Firstly, we dispersed TiO2 nanoparticles in polyacrylonitrile (PAN) solution to develop a composite of TiO2 and electrospun fibers via electrospinning process Then, the composite were manufactured by carbonization at 400。C 800。C and 1000。C. The results of this study indicate that the TiO2 concentration, carbonization temperature and applied voltage have a significant effect on the characteristics of electrode and the performance of electrocatalysis. As the carbonization temperature increased, the conductivity of electrode was drastically enhanced and the major crystal structure of TiO2 transformed to rutile phase, which may conduce to the enhancement of electrocatalytic performance.

As evidenced, hydroxyl radical can be produced by TiO2/CF carbonized at 1000。C for the electrocatalytic degradation of crystal violet at voltage of 1 V. In this case, a high removal efficiency of 85% was achieved. Therefore, the TiO2 embedded electrocatalytic carbon fibers electrode shows superior electrocatalytic activity that can be driven at a relatively lower voltage. Note that we established a photovoltaic-driven electrocatalytic degradation system for technology demonstration. By converting solar energy into electric energy, the PV-powered electrocatalytic degradation system show a high potential for the degradation of water pollutants.

並列關鍵字

electrospinning ； TiO2 nanoparticle ； electrocatalysis ； photovoltaic

參考文獻

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