本文選題：制氫　切入點(diǎn)：電解水　出處：《大連理工大學(xué)》2015年博士論文

【摘要】：氣候變暖和全球能源危機(jī)迫使科學(xué)家尋找新的可再生能源,如風(fēng)能、太陽(yáng)能。但是這些新能源在時(shí)間和空間上分布不均,這就要求我們開發(fā)新技術(shù)來解決能源的儲(chǔ)存和利用問題。利用新能源發(fā)電產(chǎn)生的電力,實(shí)現(xiàn)水裂解產(chǎn)生氫氣,將電能轉(zhuǎn)化為化學(xué)燃料是發(fā)展新能源系統(tǒng)的有效方法之一。鉑是在酸性水溶液中催化活性最高的電化學(xué)產(chǎn)氫催化劑,電能轉(zhuǎn)化效率最高。但是,鉑是貴金屬,全球儲(chǔ)量低,價(jià)格昂貴。商業(yè)化的氫電解裝置迫切的需要用非貴金屬催化劑來替代鉑。因此,開發(fā)能在水相中工作的高效、穩(wěn)定、低價(jià)、低過電勢(shì)的基于非貴金屬的催化劑是實(shí)現(xiàn)電能向氫能的高效率、低成本轉(zhuǎn)化的關(guān)鍵科學(xué)問題之一論文首先設(shè)計(jì)合成了四種含有三吡啶-二叔胺結(jié)構(gòu)的氮五配位鈷配合物[(Ll)CoNCCH3]2+(Al) (L1=N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethylenediamine)/ [(Ll)CoOH2]2+(A2)、[(L2)CoNCCH3]2+(B1) (L2=N-benzyl-N,N',N'-tris(2-pyridylmethyl) propylenediamine)和 [(L2)CoOH2]2+(B2),并對(duì)其進(jìn)行了結(jié)構(gòu)表征。循環(huán)伏安和極譜電化學(xué)研究表明,配體橋連基團(tuán)由乙二胺到丙二胺的細(xì)微變化對(duì)鈷配合物的電化學(xué)性質(zhì)有明顯影響。研究發(fā)現(xiàn),在四個(gè)鈷配合物中帶有乙二胺橋連配體的鈷配合物A2在中性水溶液中-1.25 V應(yīng)用電勢(shì)下電化學(xué)產(chǎn)氫效率(TOF)為860 mol H2 (mol cat)-1 h-1 (cm2 Hg)-1,并且經(jīng)過60 h的控制電勢(shì)電解水反應(yīng)電流無明顯衰減。為了進(jìn)一步研究配體對(duì)配合物催化性質(zhì)的影響,通過改變五配位配體中的叔胺氮和吡啶氮比例合成了單核鎳配合物[(L3)NiR]2+(L3=1,1-di(2-pyridinyl)-N,N-bis (2-pyridinylmethyl)methanamine)(C1, R=CH3CN; C2, R=H2O)、[(Ll)NiR]2+(D1, R = CH3CN;D2, R=H2O)和[(L4)NiL]2+(L4=N,N'-dibenzyl-N-(2-(benzyl(2-pyridinylmethyl)amino)ethyl)-N-(2-pyridinylmethyl)-ethane-1,2-diamine) (El, R=CH3CN; E2, R=H2O),并進(jìn)行了結(jié)構(gòu)表征。電化學(xué)研究表明,配合物C1-E1在THF中的NiⅡ/NiⅠ還原電勢(shì)隨著叔胺N比例的增加明顯的向正電勢(shì)方向移動(dòng),而對(duì)更負(fù)的第二個(gè)還原過程影響不大。這些Ni單核配合物(C2-E2)都能在中性水溶液中實(shí)現(xiàn)電催化產(chǎn)氫,但相同電勢(shì)下催化活性明顯不同。D2是催化活性和穩(wěn)定性最好的催化劑。在-1.25 V電勢(shì)下,D2在中性磷酸緩沖溶液中的TOF值為1650 mol H2 (mol cat)-1 h-1(cm2 Hg)-1,是相同結(jié)構(gòu)鈷配合物A2的兩倍,是其他已報(bào)道的多氮配位非貴金屬分子催化劑的3-37倍(應(yīng)用電勢(shì)為-1.30--1.40 V)。設(shè)計(jì)合成了含有胺—吡啶五配位的銅配合物[(L1)Cu]2+(G).該配合物在pH 2.5的緩沖溶液中電催化產(chǎn)氫速率常數(shù)(Kobs)為10000 s-1,過電勢(shì)為420 mV。以G為催化劑,在pH 2.5的緩沖溶液中,-0.90 V下電解2h的催化轉(zhuǎn)化數(shù)(TON)為1.4×104mol H2(mol cat)-1 cm-2,法拉第效率96%,對(duì)應(yīng)的TOF值為2.0 mol H2 (mol cat)-1 s-1 cm-2。光譜電化學(xué)研究表明,該銅配合物催化質(zhì)子還原產(chǎn)氫經(jīng)歷兩個(gè)質(zhì)子耦合電子轉(zhuǎn)移過程：第一步質(zhì)子化發(fā)生在配體上,第二步質(zhì)子化發(fā)生在金屬銅上生成[(LlH)CuⅡ(H)]2+,然后釋放出一分子氫氣,催化劑回到起始的CuⅡ狀態(tài)。研究中發(fā)現(xiàn),當(dāng)以鉑片為對(duì)電極,以玻璃碳為工作電極在酸性水溶液中對(duì)銅配合物G進(jìn)行電解時(shí),能夠在工作電極表面發(fā)生電沉積生成活性沉積膜Cu-CuxO-Pt-1。這種鉑摻雜的銅納米催化劑在中性水溶液中表現(xiàn)出比鉑片和Pt/C還要好的催化活性；該沉積膜的Tafel斜率為44mV dec-1,交換電流密度為1.601 mA cm-2,電催化產(chǎn)氫起始過電勢(shì)≤10 mV,催化電流密度達(dá)到20 mA cm-2所需的過電勢(shì)為45 mV,催化電流密度達(dá)到500mA cm-2所需的過電勢(shì)為370 mV。Cu-CuxO-Pt-1在中性水溶液中的催化活性可以與鉑在0.5 M H2SO4中的催化活性相媲美,基于鉑的質(zhì)量活性是CuPt電極在強(qiáng)酸水溶液中催化活性的11倍。中性水溶液中,Cu-CuxO-Pt-1電極在200 mV過電勢(shì)下能夠保持～190mAcm-2催化電流密度100小時(shí)內(nèi)無衰減。
[Abstract]:Global warming and energy crisis forced scientists to search for new and renewable energy, such as wind energy, solar energy. But these new energy in time and space distribution is uneven, which requires us to develop new technology to solve the energy storage and utilization. The use of new energy power generating electricity, water will produce hydrogen cracking. Electric energy is converted into chemical fuel is one of the effective methods for the development of new energy systems. Platinum is in acidic solution, the highest catalytic activity for hydrogen production of electrochemical catalyst, power conversion efficiency is the highest. However, platinum precious metals, the world's reserves is low, the price is expensive. The hydrogen electrolysis device commercialization of the urgent need for non noble instead of platinum metal catalysts. Therefore, development can work in water efficient, stable, low-cost, low overpotential catalyst of non noble metal based on electrical energy into hydrogen energy conversion efficiency, low cost One of the key scientific problem is firstly designed four kinds of pyridine containing three di TERT amine structure n five ligand cobalt complexes [(Ll) CoNCCH3]2+ synthesis (Al) (L1=N-benzyl-N, N', N'-tris (2-pyridylmethyl) ethylenediamine) / (Ll) CoOH2]2+ (A2), [(L2) CoNCCH3]2+ (B1) (L2=N-benzyl-N, N', N'-tris (2-pyridylmethyl) propylenediamine) and [(L2) CoOH2]2+ (B2), and it was characterized by cyclic voltammetry and polarography. Electrochemical studies showed that the ligand bridging group by ethylenediamine to slight changes in C two amines have obvious effects on the electrochemical properties of cobalt complexes. The study found that in four with Ethylenediamine bridged cobalt cobalt complexes A2 in neutral aqueous solution of -1.25 V application potential in electrochemical hydrogen production efficiency (TOF) of 860 mol H2 (mol cat) -1 H-1 (cm2 Hg -1), and through the controlled potential electrolysis water reaction current of 60 h of ignorance Significant attenuation. In order to further study the influence on catalytic properties of ligand coordination, by changing the five ligand in the tertiary amine nitrogen and pyridine nitrogen proportion of synthesis of mononuclear nickel complex [(L3) NiR]2+ (L3=1,1-di (2-pyridinyl) -N, N-bis (2-pyridinylmethyl) methanamine) (C1, R=CH3CN; C2, R=H2O), [(Ll) NiR]2+ (D1, R = CH3CN; D2, R=H2O) and [(L4) NiL]2+ (L4=N, N'-dibenzyl-N- (2- (benzyl (2-pyridinylmethyl) amino) ethyl) -N- (2-pyridinylmethyl) -ethane-1,2-diamine (El), R=CH3CN; E2, R, =H2O) and characterized. The electrochemical study shows that Ni /Ni I, II complexes of C1-E1 in THF with the reduction potential of tertiary amine N ratio significantly increased to the positive potential direction, while the second reduction process has little effect on the more negative. These Ni complexes (C2-E2) can realize the electrocatalytic hydrogen production in neutral aqueous solution, but the same catalytic potential live 鎬ф槑鏄句笉鍚，

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