【摘要】：在當(dāng)前能源危機(jī)和環(huán)境污染嚴(yán)重的背景下,開發(fā)高效清潔能源變得十分迫切。染料敏化太陽能電池(Dye-sensitized solar cells, DSCs)由于具有能量轉(zhuǎn)換效率高、易制作、低成本、環(huán)境友好等優(yōu)點而引起廣泛關(guān)注,目前效率已經(jīng)達(dá)到14%。燃料電池(Fuel cells, FCs)作為新型發(fā)電裝置,可以直接將燃料的化學(xué)能轉(zhuǎn)化為電能,具有能量轉(zhuǎn)換效率高、環(huán)境污染小、燃料來源廣等優(yōu)點,被譽為繼水力、火力和核能之后的第四代發(fā)電技術(shù)。這兩種新能源器件的研究將有助于能源危機(jī)和環(huán)境污染問題的解決。這兩種新能源器件都涉及到陰極催化還原反應(yīng),開發(fā)高效、廉價、穩(wěn)定的陰極催化材料對推動其產(chǎn)業(yè)化發(fā)展意義重大。目前DSCs和FCs中最常用的陰極材料是貴金屬鉑(Pt),其價格昂貴且造成電池成本高；另外,Pt具有穩(wěn)定性差、反應(yīng)遲緩、易受燃料滲透影響等缺點。因此,為推動兩種新能源器件的產(chǎn)業(yè)化發(fā)展,研究開發(fā)高效、低成本、高穩(wěn)定性的非貴金屬陰極催化材料成為一個迫切任務(wù)。同時需深入研究陰極催化材料在器件中的催化機(jī)理,探索電池效率的影響機(jī)制,為研究新材料提供指導(dǎo)。為解決上述問題,本論文以設(shè)計合成高效穩(wěn)定的非貴金屬陰極催化劑為目標(biāo),系統(tǒng)研究了催化材料的形貌、組成、結(jié)構(gòu)與催化性能的構(gòu)效關(guān)系,深入探索了非貴金屬催化材料對I3- (IRR, Iodine reduction reaction)和O2 (ORR, Oxygen reduction reaction)還原反應(yīng)的催化機(jī)制。首先,以NbSe2為切入點,通過控制合成過程的降溫速率實現(xiàn)了對NbSe2納米催化材料的形貌調(diào)控,研究了催化劑形貌與其對DSCs中13-/I-電對催化性能之間的關(guān)系。以NbSe2/C為對電極的DSCs最終獲得了7.80%的能量轉(zhuǎn)換效率,性能接近濺射Pt電極。通過改變過渡金屬硒化物的組成,合成了Cr5.6Se8、MoSe2、WSe2、TaSe2和HfSe3等系列硒化物,研究了材料組成與其催化性能的關(guān)系,并利用泛函密度理論對具有相似形貌和結(jié)構(gòu)但催化活性差異較大的MoSe2和WSe2進(jìn)行了理論研究,發(fā)現(xiàn)兩種催化劑催化活性差異的原因是對13-的吸附能力和電子傳導(dǎo)能力不同。進(jìn)一步拓寬了硒化物的應(yīng)用范圍,設(shè)計構(gòu)建了超薄二維石墨烯-無機(jī)石墨烯類似物層狀復(fù)合催化劑并應(yīng)用于燃料電池氧還原反應(yīng)。復(fù)合催化劑具有更高的比表面積和更加優(yōu)異的結(jié)構(gòu),更加有利于02的吸附和傳質(zhì),從而表現(xiàn)出優(yōu)異的ORR反應(yīng)催化性能。其次,首次將碲化物用作DSCs高效對電極催化材料。利用復(fù)合堿媒介法成功合成了CoTe和NiTe2,并用作對電極,DSCs器件獲得了6.92%和7.21%的光電轉(zhuǎn)換效率,與濺射Pt對電極相當(dāng)。調(diào)控鐵基化合物的組成,合成了FeS2、FeSe2和FeTe2三種鐵基硫?qū)倩衔锊?yīng)用于DSCs對電極體系,三者對13-/I-電對均表現(xiàn)出良好的電催化活性,電池效率分別為8.00%、7.92%和7.21%。其中FeTe2微米級的尺寸導(dǎo)致其催化活性位點相對較少,從而表現(xiàn)出稍差的電催化性能。理論計算表明FeS2對I具有較大的吸附能,而FeTe2則具有較小的功函數(shù),有利于界面電荷交換。第三,利用溶劑熱法在石墨烯表面合成了W18049納米棒,并將其用作燃料電池陰極催化劑。原位復(fù)合得到的催化劑中,W18049納米棒與部分還原氧化石墨烯之間存在強(qiáng)烈的相互作用。結(jié)合W18049納米棒的一維結(jié)構(gòu)、豐富的表面氧空位,以及石墨烯良好的導(dǎo)電性,合成出的復(fù)合催化劑有效保障了02的吸附和電荷的傳輸,最終表現(xiàn)出了良好的ORR催化性能。研究表明,復(fù)合催化劑在ORR過程中電子轉(zhuǎn)移數(shù)大約為3.88,與商業(yè)Pt/C催化劑接近。同時,該復(fù)合催化劑還具有良好的耐久性和抗甲醇性能,是一種有潛力的非Pt陰極催化材料。
[Abstract]:In the background of the current energy crisis and environmental pollution, it is very urgent to develop high-efficiency clean energy. Dye-sensitized solar cells (DSCs) have attracted wide attention due to the advantages of high energy conversion efficiency, easy production, low cost and environmental protection. The present efficiency has reached 14%. The fuel cell (FCs), as a new type of power generation device, can directly convert the chemical energy of the fuel into electric energy, and has the advantages of high energy conversion efficiency, small environmental pollution, wide fuel source and the like, and is praised as the fourth generation power generation technology following hydraulic, fire and nuclear power. The research of these two new energy devices will help solve the energy crisis and the problem of environmental pollution. The two new energy devices are involved in the catalytic reduction reaction of the cathode, and the high-efficiency, low-cost and stable cathode catalytic material is important for promoting the industrial development of the cathode. At present, the most common cathode materials in DSCs and FCs are noble metal platinum (Pt), which is expensive and has high battery cost; in addition, Pt has the disadvantages of poor stability, slow reaction, and easy to be influenced by fuel permeation. Therefore, in order to promote the industrialization development of two new energy devices, the research and development of the non-noble metal cathode catalytic material with high efficiency, low cost and high stability has become an urgent task. At the same time, it is necessary to study the catalytic mechanism of the cathode catalytic material in the device, to explore the mechanism of the effect of the efficiency of the battery, and to provide guidance for the study of new materials. In order to solve the above problems, this paper aims to design and synthesize a highly efficient and stable non-noble metal cathode catalyst. The structure, composition, structure and catalytic performance of the catalytic material are studied, and the non-noble metal catalytic material pair I3-(IRR, Iodine reduction reaction)鍜孫2 (ORR, Oxygen reduction reaction)榪樺師鍙嶅簲鐨勫偓鍖栨満鍒，

本文編號：2336220