本文選題：Co基納米線 + Ni/Fe-水滑石�。� 參考：《哈爾濱工業(yè)大學》2017年碩士論文

【摘要】：近年來,由于環(huán)境污染的加重和傳統(tǒng)化石燃料的短缺,人們越來越重視清潔能源的使用。在各種新能源中,與太陽能和風能相比,氫能具有便于儲存、不受氣象條件影響等優(yōu)點。若實現(xiàn)氫能的大范圍應(yīng)用,可以在很大程度上緩解、解決化石燃料短缺和環(huán)境污染等難題。在各種制氫方法中,電解水制取氫氣具有能量利用率高和操作簡單等優(yōu)點,是最有希望成為一種大范圍應(yīng)用的生產(chǎn)氫氣的方法。但是,在實際生產(chǎn)過程中,需要使用到貴金屬催化劑,由于其價格昂貴無法進行大規(guī)模生產(chǎn)。因此,制備一種可代替貴金屬且價格低廉的高效催化劑,對于電解水制氫的工業(yè)化生產(chǎn)至關(guān)重要。過渡金屬氧化物,由于具有良好的催化性能、低廉的價格被認為是貴金屬氧化物催化劑的一種有效替代品。其中Co_3O_4和Ni/Fe-水滑石等催化劑,由于具有良好的催化性能、易于制備等優(yōu)點已經(jīng)被廣泛研究。催化反應(yīng)通常發(fā)生在催化劑的表面,因此催化劑的幾何結(jié)構(gòu)將會對催化性能產(chǎn)生較大的影響。通常,氧化物催化劑材料由于導電性差或催化劑比表面積較小等缺點,而影響催化性能的發(fā)揮。本文采用水熱法,通過在還原氣氛煅燒的方式分別制備導電性良好的Co_3O_(4-x)和Co納米線陣列,最后將上述納米線陣列與高催化活性的Ni/Fe-水滑石復合構(gòu)建多級陣列電極,兩種材料起到協(xié)同效應(yīng)從而提高Co基催化劑的性能,多級結(jié)構(gòu)可以最大程度的暴露催化劑的活性表面,增大活性位點與電解液的接觸面積,從而提高催化效率。首先,通過水熱法在不銹鋼網(wǎng)上原位生長出Co基納米線前驅(qū)體,將前驅(qū)體在空氣中高溫煅燒轉(zhuǎn)化為Co_3O_4納米線陣列,再經(jīng)NaBH4處理在Co_3O_4引入氧空位,隨后通過電沉積的方式,成功地在陣列表面生長Ni/Fe-水滑石納米片,構(gòu)建Co_3O_(4-x)@LDH多級結(jié)構(gòu)。電化學測試結(jié)果表明,其在30 mA×cm-2電流密度下析氧過電位為272 m V,Tafel斜率為85.5 mV×dec-1;在10 mA×cm-2電流密度下析氫過電位為-284 mV,Tafel斜率為-72 m V×dec-1,催化性能均優(yōu)于未處理的Co_3O_(4-x)納米線陣列。隨后,為了進一步提高催化劑導電性,將Co基納米線前驅(qū)體在氫氬氣氛下高溫處理,制備金屬Co納米線陣列,金屬Co納米陣列具有更好的導電性。在Co納米線表面電沉積Ni/Fe-水滑石納米片,成功構(gòu)建Co@LDH多級結(jié)構(gòu)并測試其Co@LDH多級結(jié)構(gòu)的全解水性能。結(jié)果表明,在30 m A×cm-2電流密度下析氧過電位為262 mV,Tafel斜率為39.8 m V×dec-1,析氫過電位為-265 mV,Tafel斜率為-65 mV×dec-1,在經(jīng)過50000 s的反應(yīng)后催化活性基本不變,展示出了良好的穩(wěn)定性。
[Abstract]:In recent years, more and more attention has been paid to the use of clean energy due to the worsening of environmental pollution and the shortage of traditional fossil fuels. Compared with solar and wind energy, hydrogen energy has the advantages of convenient storage and no influence of meteorological conditions. If the hydrogen energy is widely used, it can alleviate the shortage of fossil fuels and solve the problems of environmental pollution to a great extent. Among the various hydrogen production methods, electrolytic water for hydrogen production has the advantages of high energy efficiency and simple operation, which is the most promising method for hydrogen production in a wide range of applications. However, in the actual production process, precious metal catalysts need to be used, because of their high prices can not be large-scale production. Therefore, it is very important for the industrial production of hydrogen by electrolytic water to prepare a high efficient catalyst which can replace precious metals. Transition metal oxides are considered as an effective substitute for noble metal oxide catalysts due to their good catalytic properties. Among them, Co_3O_4 and Ni / Fe- hydrotalcite catalysts have been widely studied because of their good catalytic performance and easy preparation. The catalytic reaction usually takes place on the surface of the catalyst, so the geometry of the catalyst will have a great influence on the catalytic performance. Usually, the performance of oxide catalysts is affected because of their poor conductivity or low specific surface area. In this paper, by hydrothermal method and calcination in the reduction atmosphere, we prepared CoSZ _ 3O _ (4-x) and Co nanowire arrays with good electrical conductivity respectively. Finally, the nanowire arrays were combined with Ni / Fe-hydrotalcite with high catalytic activity to form multistage array electrodes. The two kinds of materials play a synergistic effect so as to improve the performance of Co-based catalysts. The multilevel structure can maximize the exposure of the active surface of the catalyst and increase the contact area between the active sites and the electrolyte thus improving the catalytic efficiency. First of all, Co nanowire precursors were grown in situ on stainless steel by hydrothermal method. The precursors were calcined in air at high temperature to form Co_3O_4 nanowire arrays, then oxygen vacancies were introduced into Co_3O_4 by NaBH4 treatment, and then electrodeposited. The Ni / Fe-hydrotalcite nanocrystals were successfully grown on the surface of the array and the multilevel structure of Co_3O_(4-x)@LDH was constructed. The results of electrochemical measurement show that the overpotential of oxygen evolution is 272mV / cm-2 at 30 Ma 脳 cm-2 current density, the slope is 85.5 MV 脳 dec-1 and the overpotential of hydrogen evolution is -284mV / cm-2 Tafel slope of -72mV 脳 dec-1 at the current density of 10mA 脳 cm-2, which is superior to the untreated Co3OOt4-x nanowire array. Then, in order to further improve the conductivity of the catalyst, the Co nanowire precursor was treated in hydrogen argon atmosphere at high temperature to prepare the metal Co nanowire array, and the metal Co nanowire array had better electrical conductivity. Ni / Fe- hydrotalcite nanocrystals were electrodeposited on the surface of Co nanowires. The multistage structure of Co@LDH was successfully constructed and its Co@LDH multilevel structure was tested. The results show that the slope of oxygen evolution overpotential is 39.8 MV 脳 dec-1 at 30 Ma 脳 cm-2 current density, and the slope of hydrogen evolution overpotential is -65 MV 脳 dec-1 at 30 Ma 脳 cm-2 current density. After the reaction of 50000 s, the catalytic activity is almost unchanged, showing good stability.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB383.1;O643.36

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本文編號：1833751