本文選題：石墨烯　切入點(diǎn)：納米晶　出處：《鄭州大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：氫氧燃料電池作為一種清潔的能源體系引發(fā)了越來越多的關(guān)注,氫能的儲(chǔ)存是該技術(shù)取得突破的關(guān)鍵問題。由于快速充放電、可靠的穩(wěn)定性和長的循環(huán)壽命等優(yōu)勢,可充電鋰離子電池(LIBs)一直是便攜設(shè)備的主要?jiǎng)恿碓础８鞣N各樣的過渡金屬氧化物由于其具有較高的催化活性和大于商業(yè)碳質(zhì)陽極的高理論比容量,而得到研究者的廣泛青睞,同時(shí)結(jié)合石墨烯優(yōu)異的物理化學(xué)性能,應(yīng)用在催化和電極材料方面將會(huì)取得滿意的效果。本文以石墨烯為載體,合成了一系列基于石墨烯的二維材料用于硼氫化鈉水解制氫以及石墨烯包覆的三維材料用于鋰離子電池負(fù)極材料。采用紫外可見光譜、X射線衍射儀、透射電子顯微鏡、比表面及孔徑分析儀、X射線光電子能譜等技術(shù)對其形貌和結(jié)構(gòu)進(jìn)行表征,并對其催化產(chǎn)氫性能和電化學(xué)性質(zhì)做了詳細(xì)的測試和討論。以油胺為保護(hù)劑,采用溶劑熱的方法合成了小尺寸、分散性較好的Co_3O_4納米晶,以此為前驅(qū)體與不同氧化程度的石墨烯進(jìn)行復(fù)合,經(jīng)過高溫煅燒過程分別得到了負(fù)載鈷氧化物納米晶的多孔石墨烯和生長有碳纖維的石墨烯材料CoO_x-PG和CoO_x-GCNFs。在煅燒過程中,Co_3O_4納米晶作為蝕刻劑與石墨烯之間發(fā)生碳熱反應(yīng)而得到還原,在石墨烯上蝕刻出均勻的孔,以及催化碳纖維在石墨烯表面的生長,這也是本文的創(chuàng)新所在。CoO_x-PG和CoO_x-GCNFs用于催化硼氫化鈉(NaBH4)水解產(chǎn)氫,在30℃產(chǎn)氫速率分別達(dá)到1472 m L·min-1·gCo-1和2696 mL·min-1·gCo-1,這種顯著的催化活性歸因于CoO_x和PG/GCNFs之間的協(xié)同作用,小尺寸的CoO_x納米晶具有較高的催化活性,PG/GCNFs作為二維的基底,可以阻止納米晶的團(tuán)聚和提供更多的催化位點(diǎn)。另外,這兩種催化劑在催化過程中產(chǎn)生的磁性,一方面利于催化劑回收重復(fù)利用,另一方面可以利用磁性傳動(dòng)作用控制催化劑與NaBH4溶液的接觸來控制產(chǎn)氫反應(yīng)的發(fā)生和停止。綜上,這兩種催化劑可以作為廉價(jià)、高效的催化劑。以四水乙酸鈷為前驅(qū)體,通過溶劑熱法得到了花狀結(jié)構(gòu)的四氧化三鈷微球(Co_3O_4-MS),然后與石墨烯進(jìn)行復(fù)合包覆,并以水合肼對石墨烯進(jìn)行還原,得到了氮摻雜-石墨烯包覆的四氧化三鈷微球(Co_3O_4-MS@NG)。得到的Co_3O_4-MS,尺寸均一,是有許多超薄的納米片自組裝而成,具有介孔結(jié)構(gòu)。將Co_3O_4-MS和Co_3O_4-MS@NG用作LIBs陽極材料,在0.2 C下100次循環(huán)后,容量分別達(dá)到342.4 m A·h·g-1和407.5 mA·h·g-1,同時(shí)庫倫效率接近100%,高倍率充放電后,仍能回到較高的容量值,電化學(xué)阻抗較小,滿足LIBs陽極材料的性能要求。這種優(yōu)越性能歸因于獨(dú)特的帶有孔隙的三維結(jié)構(gòu)以及外層包覆的氮摻雜還原氧化石墨烯為電子的快速傳輸提供通道。
[Abstract]:As a clean energy system, hydrogen-oxygen fuel cell (HFC) has attracted more and more attention. Hydrogen energy storage is a key problem in this technology. Due to the advantages of rapid charge and discharge, reliable stability and long cycle life, Rechargeable lithium-ion battery (Libs) has been the main power source of portable devices. Various transition metal oxides have been widely used by researchers because of their high catalytic activity and high theoretical specific capacity larger than commercial carbon anodes. In combination with the excellent physical and chemical properties of graphene, satisfactory results will be obtained in catalysis and electrode materials. A series of graphene based two-dimensional materials were synthesized for hydrolysis of sodium borohydride to produce hydrogen and three dimensional materials coated with graphene for negative electrode materials of lithium ion batteries. The morphology and structure of the catalyst were characterized by X-ray photoelectron spectroscopy (XPS), and the catalytic and electrochemical properties of the catalyst were tested and discussed in detail. Co_3O_4 nanocrystals with small size and good dispersion were synthesized by solvothermal method. The porous graphene loaded with cobalt oxide nanocrystals and the graphene materials CoO_x-PG and CoOx-GCNFsgrown with carbon fiber were obtained by high temperature calcination. The homogeneous pores etched on graphene and the catalytic growth of carbon fibers on graphene surface are also the innovations of this paper. CoOx-PG and CoO_x-GCNFs are used to catalyze the hydrolysis of NaBH4 to produce hydrogen. The hydrogen production rate at 30 鈩，

本文編號：1626890