非負(fù)載型銅基合金納米管的制備及其電催化性能的研究
發(fā)布時間：2018-11-01 19:16
【摘要】：本文通過電化學(xué)置換法,利用銅納米線作為犧牲模板,通過調(diào)節(jié)金屬鹽前驅(qū)體種類、濃度以及反應(yīng)溫度制備了高長徑比的銅基合金納米管。重點(diǎn)研究了合金的成分、晶體結(jié)構(gòu)對其電催化的性能的影響規(guī)律,為開發(fā)非負(fù)載型納米電催化材料提供了基礎(chǔ)數(shù)據(jù)支持。首先,不同合金比例的銅鈀合金納米管,其直徑在100nm左右,長度約幾微米,壁厚20nm左右。在催化氧氣還原反應(yīng)過程中,不同合金比例銅鈀合金納米管在催化氧氣還原反應(yīng)中Cu45Pd55具有最好的催化活性并且比商業(yè)Pt/C更好。根據(jù)動力學(xué)相關(guān)參數(shù)的計(jì)算,發(fā)現(xiàn)Cu45Pd55有著最大的交換電流密度證明了其催化速率最快,具有更好的催化活性。XPS表明Cu的加入引起了Pd 3d軌道結(jié)合能的變化。活性提高的原因可以歸結(jié)于合適的Pd的3d結(jié)合能可以提高催化活性。并且在甲醇氧化測試中,Cu45Pd55表現(xiàn)出了優(yōu)異的催化活性,其質(zhì)量比活性為商業(yè)Pt/C的2.33倍。其活性增強(qiáng)的原因主要是Cu的加入使得Pd失電子,促進(jìn)了甲醇中C-H鍵的斷裂,并且促進(jìn)生成了大量的Pd-OHad加快了中間產(chǎn)物的氧化,從而提高了催化活性和抗CO中毒能力。其次,通過加入CuCl的絡(luò)合劑Na2S2O3證明了在Cu和PdCl2發(fā)生的置換反應(yīng)中反應(yīng)路徑為先生成CuCl,之后CuCl歧化分解生成Cu和Cu2+,由于柯肯達(dá)爾效應(yīng)最終形成了中空管狀結(jié)構(gòu)。最后,通過加入Na2S2O3作為添加劑,利用電化學(xué)置換法,制備了銅基非晶態(tài)合金納米管,確定其非晶態(tài)結(jié)構(gòu),制備得到的納米管制直徑在100nm左右,長度在幾微米,壁厚15nm左右。在甲醇氧化性能測試中,銅鉑非晶態(tài)合金納米管具有比晶態(tài)的銅鉑合金和商業(yè)Pt/C更好的催化能力和抗CO毒化能力,CO起始氧化電位比起商業(yè)Pt/C負(fù)了70mV。甲醇電催化氧化動力學(xué)過程的研究結(jié)果表明：其活性增強(qiáng)的原因是促進(jìn)了甲醇的吸附和活化,并且促進(jìn)了Pt-OHad的生成,加速Pt-COad的氧化,最終提高了催化活性。
[Abstract]:In this paper, copper alloy nanotubes with high aspect ratio were prepared by electrochemical replacement method and copper nanowires as sacrificial templates, by adjusting the type, concentration and reaction temperature of metal salt precursors. The effect of the composition and crystal structure of the alloy on its electrocatalytic performance was studied, which provided the basic data support for the development of unsupported nano-electrocatalytic materials. First of all, the diameter, length and wall thickness of copper-palladium alloy nanotubes with different ratios are about 100nm, several microns and 20nm respectively. In the process of catalytic oxygen reduction, Cu45Pd55 has the best catalytic activity and is better than commercial Pt/C in the process of catalytic oxygen reduction. According to the calculation of the kinetic parameters, it is found that Cu45Pd55 has the highest exchange current density, which proves that it has the fastest catalytic rate and better catalytic activity. XPS indicates that the addition of Cu causes the change of the binding energy of Pd 3D orbital. The reason for the increase of activity can be attributed to the suitable 3D binding energy of Pd can improve the catalytic activity. In methanol oxidation test, Cu45Pd55 showed excellent catalytic activity, and its mass specific activity was 2.33 times that of commercial Pt/C. The main reason for the enhancement of the activity is that the addition of Cu makes Pd lose electrons, promotes the breaking of C-H bond in methanol, and accelerates the formation of a large number of Pd-OHad to accelerate the oxidation of intermediate products, thus enhancing the catalytic activity and the ability of resisting CO poisoning. Secondly, it is proved that the reaction path in the substitution reaction between Cu and PdCl2 is that CuCl, is first formed, then CuCl is decomposed to Cu and Cu2, and finally the hollow tubular structure is formed due to the Kokkendal effect by adding CuCl to the complex agent Na2S2O3. Finally, by adding Na2S2O3 as additive, copper based amorphous alloy nanotubes were prepared by electrochemical replacement method. The amorphous structure of the nanotubes was determined. The nanowire diameter of the nanotubes was about 100nm, the length was several microns and the wall thickness was about 15nm. In methanol oxidation test, Cu-Pt amorphous nanotubes have better catalytic ability and anti-CO toxicity than Cu-Pt alloy and commercial Pt/C. The initial oxidation potential of CO is 70 MV lower than that of commercial Pt/C. The results of kinetic study on methanol electrocatalytic oxidation showed that the reason for the enhancement of methanol activity was that it promoted the adsorption and activation of methanol, promoted the formation of Pt-OHad, accelerated the oxidation of Pt-COad, and finally enhanced the catalytic activity.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1;O643.36
[Abstract]:In this paper, copper alloy nanotubes with high aspect ratio were prepared by electrochemical replacement method and copper nanowires as sacrificial templates, by adjusting the type, concentration and reaction temperature of metal salt precursors. The effect of the composition and crystal structure of the alloy on its electrocatalytic performance was studied, which provided the basic data support for the development of unsupported nano-electrocatalytic materials. First of all, the diameter, length and wall thickness of copper-palladium alloy nanotubes with different ratios are about 100nm, several microns and 20nm respectively. In the process of catalytic oxygen reduction, Cu45Pd55 has the best catalytic activity and is better than commercial Pt/C in the process of catalytic oxygen reduction. According to the calculation of the kinetic parameters, it is found that Cu45Pd55 has the highest exchange current density, which proves that it has the fastest catalytic rate and better catalytic activity. XPS indicates that the addition of Cu causes the change of the binding energy of Pd 3D orbital. The reason for the increase of activity can be attributed to the suitable 3D binding energy of Pd can improve the catalytic activity. In methanol oxidation test, Cu45Pd55 showed excellent catalytic activity, and its mass specific activity was 2.33 times that of commercial Pt/C. The main reason for the enhancement of the activity is that the addition of Cu makes Pd lose electrons, promotes the breaking of C-H bond in methanol, and accelerates the formation of a large number of Pd-OHad to accelerate the oxidation of intermediate products, thus enhancing the catalytic activity and the ability of resisting CO poisoning. Secondly, it is proved that the reaction path in the substitution reaction between Cu and PdCl2 is that CuCl, is first formed, then CuCl is decomposed to Cu and Cu2, and finally the hollow tubular structure is formed due to the Kokkendal effect by adding CuCl to the complex agent Na2S2O3. Finally, by adding Na2S2O3 as additive, copper based amorphous alloy nanotubes were prepared by electrochemical replacement method. The amorphous structure of the nanotubes was determined. The nanowire diameter of the nanotubes was about 100nm, the length was several microns and the wall thickness was about 15nm. In methanol oxidation test, Cu-Pt amorphous nanotubes have better catalytic ability and anti-CO toxicity than Cu-Pt alloy and commercial Pt/C. The initial oxidation potential of CO is 70 MV lower than that of commercial Pt/C. The results of kinetic study on methanol electrocatalytic oxidation showed that the reason for the enhancement of methanol activity was that it promoted the adsorption and activation of methanol, promoted the formation of Pt-OHad, accelerated the oxidation of Pt-COad, and finally enhanced the catalytic activity.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.1;O643.36
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