發(fā)布時(shí)間：2018-01-05 10:43

  本文關(guān)鍵詞：基于多酸的光、電催化劑設(shè)計(jì)、制備及其催化性能研究　出處：《東北師范大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 多酸 復(fù)合材料 催化劑 光降解染料 電催化析氫

【摘要】：多酸全稱多金屬氧酸鹽,是一類具有豐富組成、結(jié)構(gòu)和多種化學(xué)性質(zhì)的納米級(jí)無機(jī)金屬氧簇類化合物,在光催化、電催化、質(zhì)子導(dǎo)體、藥物化學(xué)、有機(jī)催化和電致變色材料等領(lǐng)域具有潛在的應(yīng)用價(jià)值。本論文利用多酸的類半導(dǎo)體性能設(shè)計(jì)和制備了兩類新型的多酸基復(fù)合光催化劑系列,具有高效的可見光光催化降解染料活性;同時(shí)借助多酸豐富的組成和納米結(jié)構(gòu)特征設(shè)計(jì)和開發(fā)了新型的W/Mo基碳化物電催化劑,展現(xiàn)出高效的全pH電解水產(chǎn)氫性能。具體工作如下:1.設(shè)計(jì)制備了二維層狀復(fù)合光催化劑Bi_2O_xS_(3-x)/Nb6O17(Bi/Nb)。利用Bi~(3+)交換的K_4Nb_6O_(17)和硫脲,通過簡(jiǎn)單的水熱硫化過程制得Bi_2O_xS_(3-x)/Nb6O17光催化劑。XRD結(jié)果證實(shí)復(fù)合催化劑由Bi_2O_xS_(3-x)和Nb6O17組成。高分辨透射電鏡(HRTEM)表明Bi_2O_xS_(3-x)成功插層進(jìn)入K_4Nb_6O_(17)層間。該催化劑具有高效的可見光驅(qū)動(dòng)的降解典型有機(jī)染料模型甲基橙能力(λ400 nm)。自由基捕獲實(shí)驗(yàn)表明空穴h+和超氧自由基O_2~-起到重要作用。通過結(jié)構(gòu)與性能對(duì)照分析推測(cè)雜化組分間有效的界面接觸有利于光生電荷的遷移和分離,進(jìn)而提高整個(gè)雜化催化劑的催化活性。這類二維層狀復(fù)合物可作為潛在的高效可見光催化劑用于水污染處理和環(huán)境修復(fù)。2.設(shè)計(jì)制備了一系列多酸修飾的g-C_3N_4(POMs/C_3N_4)復(fù)合光催化劑。利用g-C_3N_4和各種多酸陰離子(包括SiW12O404-,PW12O403-,PMo12O403-)在水溶液中室溫反應(yīng)制得。XRD,TEM,XPS和EDAX測(cè)試證實(shí)多酸通過靜電作用和氫鍵修飾到g-C_3N_4表面。光催化實(shí)驗(yàn)證實(shí)該類復(fù)合物具有高效的可見光光降解甲基橙能力(λ400 nm),并且改變多酸的含量和種類可調(diào)節(jié)復(fù)合催化劑的光催化活性。其中,5%SiW12修飾的g-C_3N_4具有最高催化活性。催化機(jī)理研究表明多酸作為電子受體能捕獲C_3N_4的光生電子,從而促進(jìn)光生載流子的分離,導(dǎo)致光催化活性的改善。3.設(shè)計(jì)制備了一種少層N摻雜碳包裹的P修飾碳化鎢(P-W_2C@NC)電催化劑。該催化劑利用多酸H3PW12O40和二聚氰胺在氮?dú)夥障赂邷仂褵玫�。該催化劑展現(xiàn)出高效的電解水產(chǎn)氫性能,并可在全pH范圍內(nèi)具有高催化活性。電催化測(cè)試證實(shí)在酸性(pH=0),堿性(pH=14)和中性(pH=7)的溶液中,當(dāng)電流密度達(dá)到10 m A cm~(-2)時(shí),P-W_2C@NC需要過電位89 mV,63 mV和185 mV。此外,該催化劑也在全pH范圍內(nèi)展示良好的穩(wěn)定性。通過量化計(jì)算并結(jié)合實(shí)驗(yàn)結(jié)果分析得出,W_2C與氮摻雜碳層的復(fù)合,可有效降低催化劑的氫原子吸附自由能,提高電催化活性;此外P的摻雜也有效提高了催化活性。更重要的是少層碳?xì)げ粌H有效防止了W_2C納米粒子在形成過程中的聚集和板結(jié),而且保護(hù)了電催化劑不被外界環(huán)境腐蝕,極大提高了穩(wěn)定性和導(dǎo)電性。這類碳層包覆和雜原子磷修飾的碳化鎢納米催化劑為開發(fā)全pH范圍的高活性和穩(wěn)定性的非貴金屬電催化析氫催化劑提供了重要的設(shè)計(jì)參考。4.設(shè)計(jì)制備了負(fù)載于氮摻雜碳層上的磷修飾碳化鉬(P-Mo_2C/NC)電催化劑。利用低廉環(huán)保的脲醛樹脂UF與H3PMo12O40在氮?dú)夥障赂邷仂褵频脧?fù)合催化劑P-Mo_2C/NC。UF的3D網(wǎng)狀結(jié)構(gòu)有利于多酸簇的單分散,能有效避免煅燒過程中的Mo_2C團(tuán)聚。所制備的復(fù)合材料中Mo_2C納米粒子具有較小尺寸(av.7 nm)和粒子尺寸均一(5~12 nm)的特點(diǎn)。該類催化劑具有高效穩(wěn)定的全pH電催化析氫活性。在酸性(pH=0),堿性(pH=14)和中性(pH=7)的溶液中,當(dāng)電流密度達(dá)到10 mA cm~(-2)時(shí),P-Mo_2C/NC需要過電位109 m V,159 mV和83 mV。此外,該催化劑也在全pH范圍內(nèi)展示良好的穩(wěn)定性。這一研究為制備高效、價(jià)廉的非貴金屬HER催化劑提供新的設(shè)計(jì)方案。
[Abstract]:The full name of Polyoxometalates POMS, which is a kind of rich composition, nano inorganic metal oxygen cluster compounds structure and a variety of chemical properties, photocatalysis, electrocatalysis, proton conductor, pharmaceutical chemistry, has potential application in catalysis and organic electrochromic materials and other fields. In this thesis, two kinds of acid composite photocatalysts were prepared by a series of new polyoxometalate semiconductor design and performance, with visible light photocatalytic degradation of dye reactive efficiently; at the same time with the more acid rich composition and nanometer structure design and development of the new W/ Mo based carbide catalysts, showing pH hydrogen water electrolysis performance the specific work as follows: 2D layered composite photocatalyst prepared Bi_2O_xS_ 1. design system (3-x) /Nb6O17 (Bi/Nb). Using Bi~ (3+) exchange K_4Nb_6O_ (17) and thiourea through a simple hydrothermal curing process to prepare Bi_2O_ XS_ (3-x) /Nb6O17 photocatalyst.XRD showed that the composite catalyst by Bi_2O_xS_ (3-x) and Nb6O17. High resolution transmission electron microscopy (HRTEM) showed that Bi_2O_xS_ (3-x) successfully intercalated into the K_4Nb_6O_ layer (17). The catalyst has high visible light driven degradation of typical organic dye methyl orange (lambda 400 nm capacity model). Radical trapping experiments show that the hole h+ and superoxide radical O_2~- play an important role. Through the comparative analysis of the structure and properties of hybrid components that effective interface facilitates the migration and separation of photogenerated charge, and then improve the catalytic activity of the catalyst. This kind of hybrid 2D layered composite material can be used as efficient visible light the catalyst potential for a series of Polyoxometalates modified to prepare g-C_3N_4 water pollution treatment and environmental remediation.2. design system (POMs/C_3N_4) composite photocatalyst. With g-C_3N_4 and polyoxoanions (package Including SiW12O404-, PW12O403-, PMo12O403-) in aqueous solution at room temperature for.XRD, TEM, XPS and EDAX test proved that the acid modified by electrostatic interaction and hydrogen bonding on the surface of g-C_3N_4. The photocatalytic experiment showed that the compound has the ability of visible light, the degradation of methyl orange (lambda 400 nm), the photocatalytic activity and change many kinds of acid content and adjustable composite catalyst. Among them, 5%SiW12 modified g-C_3N_4 exhibited the highest catalytic activity. The catalytic mechanism of multi acid as electron acceptor C_3N_4 can capture photogenerated electrons, so as to promote the separation of photogenerated carriers, resulting in a few layers of N doped carbon coated P modified tungsten carbide the preparation of.3. was designed to improve the photocatalytic activity of the catalysts (P-W_2C@NC). H3PW12O40 acid and two melamine by high temperature calcination under nitrogen using the catalyst. The catalyst exhibited high electrolytic hydrogen The performance, and has high catalytic activity in the whole range of pH. The electrocatalytic test confirmed in acid (pH=0), alkaline (pH=14) and neutral (pH=7) solution, when the current density reaches 10 m A cm~ (-2), P-W_2C@NC potential of 89 mV, 63 mV and 185 mV. in addition. The catalyst also showed good stability in the whole range of pH. Through the quantitative calculation and with the analysis and experimental results show that the composite W_2C and nitrogen doped carbon layer, can effectively reduce the hydrogen adsorption free catalyst can improve the electrocatalytic activity; in addition, the doping of P enhances the catalytic activity is more important. The less carbon shell layer not only effectively prevent W_2C nanoparticles in the formation process of the accumulation and compaction, and protect the electrocatalyst by external environmental corrosion, which greatly improves the stability and conductivity of nano tungsten carbide catalyst. This kind of carbon coated and heteroatom phosphorus modified for development The full range of pH with high activity and stability of non noble metal catalyst for hydrogen evolution provides a modified phosphorus molybdenum carbide supported on nitrogen doped carbon layer on the preparation of.4. design for important reference design (P-Mo_2C/NC) electrocatalysts. 3D network structure using urea formaldehyde resin UF and H3PMo12O40 environmental protection low in nitrogen atmosphere at high temperature calcined composite catalyst P-Mo_2C/NC.UF for polyoxomolybdate cluster monodisperse, can effectively avoid the calcination process of Mo_2C agglomeration. For Mo_2C nanoparticles composite material prepared with smaller size (av.7 nm) and uniform particle size (5~12 nm). The characteristics of this kind of catalyst has high efficiency and stability of the whole electric catalytic pH the activity of hydrogen evolution. In acid (pH=0), alkaline (pH=14) and neutral (pH=7) solution, when the current density reaches 10 mA cm~ (-2), P-Mo_2C/NC need to have a potential of 109 m V, 159 mV and 83 mV. in addition, the catalyst is in full pH fan It shows good stability in the enclosure. This study provides a new design for the preparation of efficient and inexpensive non precious metal HER catalysts.

【學(xué)位授予單位】：東北師范大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 吳聰萍;周勇;鄒志剛;;光催化還原CO_2的研究現(xiàn)狀和發(fā)展前景[J];催化學(xué)報(bào);2011年10期

2 ;Preparation and Photocatalytic Properties of g-C_3N_4 /TiO_2 Hybrid Composite[J];Journal of Materials Science & Technology;2010年10期

3 袁堅(jiān);陳愷;陳銘夏;上官文峰;;層間插入CDS/ZNS的K_4NB_6O_(17)的制備及其光解水制氫研究[J];太陽(yáng)能學(xué)報(bào);2005年06期

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本文編號(hào)：1382786