| 摘要: | CHINESE ABSTRACT
在過去五年中鈉離子電池（SIB）受到了極大的關注，因為他被視為是鋰離子電池（LIB）的未來替代品，主要的原因是由於鈉在地殼中藏量豐富且價格較為低廉。然而，Na +相對於Li +有較大的離子半徑，導致在充放電循環時體積膨脹較為顯著以及較低的能量密度，使得在開發鈉離子電池的陽極材料上仍然有相當大的挑戰。此博士論文的工作目的在於透過設計具有高功率性能的奈米材料來解決以上這些問題。在此工作中，我們開發出一系列具有不同形態的氧化銅（CuO）奈米材料，包含奈米棒、奈米橢圓體和奈米片…等。透過X射線繞射、TEM和Ex-situ XRD等技術，建立了晶體結構與電化學性能的關係。
此外，為了克服傳統問題，開發具有良好結構特性（如形態，結晶度和孔隙率）的新型碳質材料作為高性能SIB的理想碳基質是非常重要的。孔洞結構會影響其電化學行為，如容量，循環效率和速率能力。有序介孔碳材（OMC）中孔洞的排列可能對鈉離子遷移性質有顯著的影響。通過奈米鑄造法合成了CMK-3和CMK-8等有序介孔碳材，並對其進行了系統性的分析，藉此了解CMK-3和CMK-8的結構對SIBs電化學性能的影響。奈米等級的過渡金屬氧化物與OMC的複合物使用可能是解決SIB陽極材料問題最有效方法。另一方面，CMK-3和CMK-8被認為是CuO奈米顆粒的優良骨架和高導電性基體。為了達到高功率SIB的要求，運用水熱合成法製備CuO @ CMK-3和CuO @ CMK-8奈米複合材料。 CuO @ CMK-3和CuO @ CMK-8陽極材料透過各種技術，來評估其結構和電化學性質。從實驗的數據能夠深入的瞭解CuO @ CMK-3和CuO @ CMK-8系統中電化學分解/去除過程中的轉化反應機理。此外，不同孔洞結構的電極、Na的嵌入/嵌出原理、電極上SEI層的反應機理，電解質中電荷轉移的闡釋，電極界面和通過SEI層的鈉離子傳輸進行了詳細的探討。以上所製備的CuO @ CMK-8奈米複合材料顯示出高可逆的鈉儲存能力和優異的SIB的可循環性是相當具有前景的陽極材料。
本博士論文的第二個部分是透過簡單實用的合成方法開發出有效的光催化劑，如:還原4-硝基苯酚和光催化產氫。在這部分，我們製備出不同型態的金屬銅/銅金屬氧化物和有序介孔碳材複合物，如Cu @ CMK-8, CuO@CMK-8和Cu2O @ CMK-8…等，並將其利用在光催化劑上，並比較光催化劑在還原硝基苯酚的催化活性。為了研究非貴重金屬異質結構催化劑對4-硝基苯酚還原以及光催化產氫的影響，我們利用簡易的水熱技術合成出TiO2 @ CMK-8的複合材料，再透過濕式浸漬法合成Ni-TiO2@ CMK-8。從實驗數據可知，Ni-TiO2@ CMK-8複合材料中Ni和CMK-8之間的協同相互作用，有效的改善了光催化產氫以及4-硝基苯酚的還原之效能。在進行了系統化的分析後，發現對光催化產氫以及4-硝基苯酚的還原來說，非貴金屬有序介孔碳材催化劑是相當具有潛力的。
;ENGLISH ABSTRACT
Regarded as future alternatives for Lithium ion batteries (LIBs), Sodium ion batteries (SIBs) have received tremendous attention during the last five years, mainly due to the worldwide abundance of Na and the significant cost-effective advantages. However, the development of suitable anode materials for Na-ion batteries remains a considerable challenge in view of the larger ionic radius of Na+ with respect to Li+ which leads to a higher volume expansion upon cycling and lower gravimetric and volumetric energy densities. This doctoral work aims to address these problems by designing nanomaterials with high power performance. Herein, a series of nanostructured materials specifically copper oxide (CuO) with different morphology: nanorod, nano ellipsoid and nano flakes structure were developed. By using X-ray diffraction, TEM and Ex-situ XRD observation techniques, the relationship between the electrode crystal structure and electrochemical performance was established.
In addition, to overcome the traditional problems, development of new carbonaceous materials with favourable structural properties, such as morphology, crystallinity, and porosity, as ideal carbon matrices for the high performance of SIBs is highly desirable. The pore arrangements affect their electrochemical behavior such as capacity, cycle efficiency, and rate capability. Different mesopore arrangements of ordered mesoporous carbons (OMCs) might have significant influences on the Na+ ion transport properties. OMCs like CMK-3 and CMK-8 were synthesized by nano casting method and a systematic analysis was carried out in order to understand the effect of key structural parameters of CMK-3 and CMK-8, on their electrochemical performances in SIBs in their pure forms without incorporation of metal oxides. The combined use of nanostructured transition metal oxides with OMCs could be an effective approach to solve the issues of anode materials for SIBs. Especially, CMK-3 and CMK-8 can be regarded as an excellent backbone and highly conductive matrices for CuO nanoparticles. To achieve the requirements for high power SIB, a hydrothermal synthesis method was applied to prepare CuO@CMK-3 and CuO@CMK-8 nanocomposites. Both the CuO@CMK-3 and CuO@CMK-8 anode materials were characterized by a variety of techniques to evaluate their structural and electrochemical properties. Direct experimental evidence provides a deep insight to the conversion reaction mechanism during the electrochemical sodiation/de-sodiation process for the CuO@CMK-3 and CuO@CMK-8 systems. Furthermore, fundamental scientific elucidation of the difference in transport and kinetic behaviors between different pore architecture based CuO@CMK electrodes, Na insertion/extraction mechanism, the reaction mechanism at solid electrolyte interphase (SEI) layer on the electrodes, charge transfer in the electrolyte-electrode interface and Na+ ion transport through the SEI layer was studied in detail. As a promising anode material, the as-prepared CuO@CMK-8 nanocomposite exhibited a high reversible sodium storage capacity and excellent cyclalibilty for SIB.
The second objective of this doctoral thesis is to develop efficient photocatalysts via simple and practical synthesis methods for catalytic application such as reduction of 4- nitrophenol and photocatalytic hydrogen generation. In this regard, different Copper based metal/metal oxide and ordered mesoporous carbon composite such as Cu@CMK-8 CuO@CMK-8 and Cu2O@CMK-8 photocatalysts were fabricated and characterized. Furthermore, the comparative performance of such photocatalysts for reduction of nitrophenol reaction were evaluated. In order to study the performance of a non-noble metal co-catalyst-semiconductor heterostructure for reduction of 4-nitrophenol as well as photocatalytic hydrogen generation, TiO2 with CMK-8 composite denoted as TiO2@CMK-8 was developed by a facile hydrothermal technique. Then, Ni-TiO2@CMK-8 was synthesized by a wet impregnation method followed by calcination at a reducing atmosphere. It was observed that the synergistic interactions between the Ni co-catalyst and the CMK-8 within the Ni-TiO2@CMK-8 composite substantially improves the solar photocatalytic hydrogen generation as well as the reduction of nitrophenol. A systematic analysis was carried out to investigate the effect of non-noble metal co-catalyst and ordered mesoporous carbon to maximize the photocatalytic hydrogen generation under solar light irradiation and catalytic reduction of nitrophenol. |
