本文選題：氧還原反應(yīng) + 氧析出反應(yīng)　； 參考：《北京化工大學(xué)》2017年碩士論文

【摘要】：鋅-空氣電池具有比能量高、容量大、成本低等優(yōu)點,在儲能和電動汽車等領(lǐng)域具有良好的應(yīng)用前景。鋅-空氣電池的核心材料是兼具氧還原(ORR)和氧析出(OER)活性的雙功能催化劑,目前多采用貴金屬(如Pt,RuO2和IrO2等),但受制于成本高昂和儲量有限,阻礙了鋅-空氣電池的商業(yè)化。因此,研究開發(fā)高效的非貴金屬雙功能催化劑具有重要意義。本文將具有微觀有序多級結(jié)構(gòu)的生物質(zhì)牛骨進(jìn)行碳化,制備了原位氮摻雜分級多孔炭(NHPC)材料,以NHPC為載體擔(dān)載四氧化三鈷(Co3O4)納米粒子,制備了 Co3O4/NHPC雙功能催化劑,研究了 Co3O4/NHPC催化劑制備條件、組成結(jié)構(gòu)對ORR和OER電催化性能的影響規(guī)律。首先,以牛骨為前驅(qū)體,采用KOH為活化劑,通過預(yù)碳化-碳化活化制備了高表面積且微孔-介孔-大孔三維連通的NHPC。研究發(fā)現(xiàn),當(dāng)KOH與預(yù)碳化產(chǎn)物質(zhì)量比為0.4時,制備的NHPC比表面積最大(2047 m2g-1),氮摻雜量為3.85%。在此基礎(chǔ)上,以NHPC為載體擔(dān)載Co3O4納米粒子,采用油浴水熱法制備了 Co3O4/NHPC復(fù)合催化劑。NHPC的超高比表面積和表面氮摻雜有利于促進(jìn)Co3O4納米粒子高度分散。當(dāng)油浴溫度80℃,氨水加入量1mL時,Co3O4納米粒子均勻地分散在炭載體上,其平均粒徑為7.2 nm,明顯小于商業(yè)Vulcan XC-72和BP2000炭材料擔(dān)載制備的催化劑。該催化劑同時保有了NHPC三維連通的孔道結(jié)構(gòu),比表面積高達(dá)1070 m2g-1,氮含量為4.93 wt.%。其次,將制備的Co3O4/NHPC作為ORR和OER雙功能催化劑,揭示了電催化性能促進(jìn)機(jī)制。研究表明,Co3O4/NHPC催化劑的ORR催化活性和穩(wěn)定性均顯著優(yōu)于商業(yè)Pt/C,其半波電位為0.835 V(比商業(yè)Pt/C高12 mV),0.8 V的動力學(xué)電流密度為15.85 mAcm-2(為商業(yè)Pt/C的3.76倍),經(jīng)10000 s恒電位計時電流測試后電流僅下降9.3%。OER性能測試表明,該催化劑在電流密度為10 mAcm-2時的電位為1.65 V,比商業(yè)RuO2高10 mV,經(jīng)10000 s恒電位計時電流測試后電流僅下降8.2%,表現(xiàn)出優(yōu)于商業(yè)RuO2的OER催化活性和穩(wěn)定性。Co3O4/NHPC催化劑優(yōu)異的ORR和OER雙功能催化活性主要歸因于高分散的Co3O4納米粒子、三維連通的分級孔結(jié)構(gòu)、高表面積以及具有協(xié)同催化作用的表面摻雜氮。最后,將Co3O4/NHPC催化劑制備空氣電極,采用鋅片為陽極組裝鋅-空氣電池,進(jìn)行了電池性能測試。結(jié)果表明,鋅-空氣電池開路電壓達(dá)到1.39 V,峰值功率密度為80 mW cm-2,顯著高于商業(yè)Pt/C作為空氣電極材料組裝的單電池(55.6 mW cm-2);在電流密度為20 mA cm-2時,電池比容量為674 mAh gZn-1(對應(yīng)能量密度768 Wh kg-1Zn),比商業(yè)Pt/C組裝的單電池高156 mAhgZn-1。該電池可在機(jī)械充電過程中穩(wěn)定運行38 h。
[Abstract]:Zinc-air battery has the advantages of high specific energy, large capacity and low cost. It has a good application prospect in energy storage and electric vehicles. The core material of zinc-air battery is a bifunctional catalyst with the activity of oxygen reductive ORR and oxygen precipitate. At present, precious metals (such as PTR, IrO2 and so on) are mostly used, but the high cost and limited reserves hinder the commercialization of zinc-air battery. Therefore, it is of great significance to develop high efficient non-noble metal bifunctional catalysts. In this paper, the biomass bovine bone with microcosmic ordered multistage structure was carbonized, and in situ nitrogen-doped fractionated porous carbon (NHPCs) material was prepared. The Co3O4/NHPC bifunctional catalyst was prepared by using NHPC as the carrier to support the cobalt trioxide Co _ 3O _ 4 nanoparticles. The effects of preparation conditions and composition of Co3O4/NHPC catalysts on the electrocatalytic properties of ORR and OER were studied. Firstly, using bovine bone as precursor and KOH as activator, high surface area NHPCs with microporous mesoporous and macroporous connectivity were prepared by pre-carbonization and carbonation activation. It is found that when the mass ratio of KOH to precarbonation product is 0.4, the maximum specific surface area of the prepared NHPC is 2047m2g-1g ~ (-1), and the nitrogen doping amount is 3.85. On this basis, the ultrahigh specific surface area and nitrogen doping of Co3O4/NHPC composite catalyst 路NHPC were prepared by oil bath hydrothermal method supported on Co3O4 nanoparticles supported on NHPC carrier, which could promote the high dispersion of Co3O4 nanoparticles. When the oil bath temperature is 80 鈩，

本文編號：1928589