【摘要】：隨著氣候變暖和化石燃料供給日益衰竭迫使人類研發(fā)各種清潔能源,燃料電池、水電解、金屬-空氣電池等各種清潔能源轉(zhuǎn)化技術(shù)成為了各國基礎(chǔ)研究和應(yīng)用研究的熱點。氧電極催化劑是制約燃料電池和水電解技術(shù)商業(yè)化的主要瓶頸之一。目前,燃料電池陰極氧還原反應(yīng)(ORR)用催化劑主要為貴金屬Pt及其合金催化劑,電解水裝置陽極氧析出反應(yīng)(OER)用催化劑主要為貴金屬RuO2、IrO2基催化劑。目前廣泛采用的氧電極貴金屬基催化劑(如鉑基、釕基、銥基等)高昂的價格和有限的儲量,己成為制約上述新能源轉(zhuǎn)化技術(shù)實際應(yīng)用的瓶頸。因此,發(fā)展高效、廉價、穩(wěn)定、選擇性好的氧電極催化劑將有力推動清潔能源設(shè)施的實用化。基于此,本文控制合成了一系列價格低廉,催化活性高,穩(wěn)定性好的雜原子摻雜氧電極催化劑。本論文以三聚氰胺和多巴胺等富氮化合物為主要原料,以海藻酸鈉為碳基材料的前驅(qū)體制備了一系列摻雜的碳基催化劑,分別深入研究了不含金屬的摻雜碳基催化劑結(jié)構(gòu)和性能;過渡金屬鈷、氮共摻雜碳基催化劑的結(jié)構(gòu)和性能;金屬鈷和三聚氰胺及硫醇多巴胺在該系列催化劑中所起的促進(jìn)作用;以及過渡金屬和氮硫共摻雜時對催化劑性能與結(jié)構(gòu)的影響。首先,高溫?zé)峤夂Ｔ逅徕c、尿素以及硫脲的復(fù)合物制備了氮硫雙摻雜的碳基催化劑,記為N/S-C。探究了溫度、負(fù)載量并通過XRD、SEM、XPS以及旋轉(zhuǎn)圓盤電極對其性能的測試,結(jié)果表明在800℃時為最佳的碳化溫度,氮硫雙摻雜二者相互作用增加活性位點,OER的起始電位23 mv,與貴金屬IrO2催化劑的催化活性相近,當(dāng)電流密度為10mA/cm~2時,其電位值僅為1.49V,其ORR的起始電位0.86V,極限擴(kuò)散電流密度為-5.83 mA/cm~2,在滴加甲醇溶液中經(jīng)過9h的測試,其起始電位和電流密度衰減程度較小,則其甲醇耐受性性較穩(wěn)定。其次,高溫?zé)峤夂Ｔ逅徕c、三聚氰胺、六水合氯化鈷復(fù)合物制備含過渡金屬鈷氮摻雜的碳基催化劑,記為Co/N-C。分別對其溫度、負(fù)載量進(jìn)行了考察,并通過XRD、SEM、BET、XPS進(jìn)行材料表征,實驗結(jié)果表明金屬鈷摻雜在氮摻雜的碳基材料其催化活性較好穩(wěn)定性較高,OER的起始電位190mv,當(dāng)電位為1.55V時其電流密度為30.2mA/cm~2,其ORR的起始電位0.88V,極限擴(kuò)散電流密度為-6.01mA/cm~2,經(jīng)過7h測試之后,其電流密度僅衰減了6%左右。最后,將多巴胺溶液、硫醇和配置好的海藻酸鈉溶液混合制備鈷氮硫多摻雜的碳基催化劑,記為N/S/Co-C,形成了含有金屬鈷水凝膠,在經(jīng)過冷凍干燥后形成氣凝膠,再通過在氮氣的氛圍下高位煅燒形成碳?xì)饽z,NS的協(xié)同作用使其更多的活性位點暴露在外面,當(dāng)加入了過度金屬鈷其催化活性得以提高,OER的起始電位220mv,當(dāng)電流密度等于10mA/cm~2,時,其電位值為1.44V,其ORR的起始電位0.89V,極限擴(kuò)散電流密度為-5.9mA/cm~2。
[Abstract]:With the increasing depletion of fossil fuel supply and climate warming, human beings are forced to develop various clean energy sources, fuel cells, water electrolysis, metal-air batteries and other clean energy conversion technologies, which have become the focus of basic research and application research in many countries. Oxygen electrode catalyst is one of the main bottlenecks restricting the commercialization of fuel cell and water electrolysis technology. At present, the catalysts for the cathodic oxygen reduction reaction (ORR) of fuel cells are mainly noble metal Pt and its alloys, and the catalysts for the anodic oxygen precipitation reaction (OER) in electrolytic water plants are mainly based on the noble metal RuO2O2IrO2. The high price and limited reserves of noble metal based catalysts (such as platinum-based, ruthenium, iridium, etc.), which are widely used at present, have become the bottleneck of the practical application of the new energy conversion technology mentioned above. Therefore, the development of efficient, cheap, stable and selective oxygen electrode catalysts will promote the utility of clean energy facilities. Based on this, a series of low cost, high catalytic activity and good stability heteroatom doped oxygen electrode catalysts were synthesized. In this paper, a series of doped carbon-based catalysts were prepared from nitrogen-rich compounds such as melamine and dopamine, and sodium alginate was used as the precursor of carbon-based materials. The structure and performance of metal-free doped carbon-based catalysts, the structure and performance of transition metal cobalt, nitrogen co-doped carbon-based catalysts, the promotive role of metallic cobalt, melamine and mercaptan dopamine in the catalysts were studied. And the effect of transition metal and nitrogen-sulfur co-doping on the performance and structure of the catalyst. Firstly, the complexes of sodium alginate, urea and thiourea were pyrolyzed at high temperature to prepare a carbon-based catalyst with double doping of nitrogen and sulfur, denoted as N / S-C. The temperature, loading amount and the properties of XRDX SEMX XPS and rotating disk electrode were investigated. The results show that the optimum carbonization temperature is 800 鈩，

本文編號：2132459