本文選題：光催化　切入點：改性　出處：《華南理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著人們對清潔能源和可再生能源的重視,光催化分解水制取氫氣已經(jīng)引起了國內(nèi)外學(xué)者的廣泛興趣。Ti O2具有強(qiáng)氧化還原能力、高穩(wěn)定性、低價格和容易獲取等特點,是備受矚目的半導(dǎo)體光催化材料之一。納米Ti O2作為半導(dǎo)體光催化材料已被廣泛應(yīng)用到光解水產(chǎn)氫、光降解污染物、大氣凈化、殺菌消毒等方面。但是由于光生載流子電荷的高復(fù)合率和本身較小比表面積,Ti O2單獨使用時催化性能并不理想。改性Ti O2以提高其光催化制氫活性,一直是富有挑戰(zhàn)并極具理論和實踐意義的課題。研究人員通過在Ti O2表面添加不同助催化劑,形成新的催化劑捕獲光生載流子缺陷,以延長光生載流子壽命,提高光催化性能。此外,不同形貌納米Ti O2,如納米棒、納米線、納米管等,被證實在形成更大比表面積同時確保光生電子的快速傳遞,因而獲得更好制氫活性。本文利用溶劑熱法合成了Ni S/Ti O2和Ni S/Ti O2納米管(TNTs)催化劑,考察了催化劑的制氫活性,探討了影響光催化效率的因素,并對其光催化機(jī)理等做了初步探討。主要工作內(nèi)容和結(jié)論如下:1.以P25、硝酸鎳和硫脲為原料,通過溶劑熱法制備納米Ni S/Ti O2光催化劑,采用XRD、TEM、UV-vis、PL等對催化劑的晶型、形貌、光響應(yīng)特性等性能進(jìn)行了測試和表征,考察了Ni S添加量對催化劑制氫活性的影響,探討了Ni S/Ti O2光催化機(jī)理。結(jié)果表明:Ni S添加量為5 wt%,催化劑用量為0.5 g/L,犧牲試劑為甲醇時,Ni S/Ti O2催化劑的產(chǎn)氫活性最佳,達(dá)3090μmol·h-1·g-1,約是純Ti O2產(chǎn)氫活性的96倍。光催化產(chǎn)氫活性提高的原因歸屬于Ni S與Ti O2形成的協(xié)同效應(yīng):1)Ni2+/Ni還原電勢(-0.23 e V)略低于Ti O2導(dǎo)帶位置(-0.26 e V),有利于Ti O2上光生電子轉(zhuǎn)移到Ni S納米簇上;2)部分Ni2+被還原成Ni單質(zhì),金屬Ni與Ti O2形成肖特基勢壘,一定程度上加速電子的轉(zhuǎn)移并抑制光生載流子的復(fù)合。2、以P25為原料,在10 M Na OH的強(qiáng)堿環(huán)境下,采用水熱法成功制備出二氧化鈦納米管(TNTs),并通過溶劑熱法制備Ni S/TNTs光催化劑,采用XRD、TEM、UV-vis、BET、PL等對催化劑的晶型、形貌、光響應(yīng)特性等性能進(jìn)行了測試,并探究Ni S添加量對光催化活性的影響,探討了Ni S/TNTs光催化反應(yīng)機(jī)理。結(jié)果表明:堿性水熱法制備的TNTs具有一維中空結(jié)構(gòu),管徑范圍為10-15 nm,比表面積達(dá)到313.79 m2·g-1,約為P25比表面積的6倍;Ni S添加量為8 wt%,催化劑用量為0.5 g/L,犧牲試劑為甲醇時,Ni S/TNTs催化劑的產(chǎn)氫活性最佳,達(dá)7486μmol·h-1·g-1。Ni S/TNTs高催化活性的原因在于TNTs的獨特結(jié)構(gòu),大的比表面積使Ni S納米簇高度分散,以形成更多還原活性位;一維電子傳輸結(jié)構(gòu)使載流子電荷定向輸,減少光生電子遷移距離,實現(xiàn)快速轉(zhuǎn)移,減少了光生電子-空穴對的復(fù)合率。
[Abstract]:With the attention paid to clean energy and renewable energy, photocatalytic decomposition of water to produce hydrogen has attracted wide interest of scholars at home and abroad. TIO 2 has the characteristics of strong redox ability, high stability, low price and easy to obtain. Nanocrystalline TIO _ 2 as semiconductor photocatalytic material has been widely used in photodegradation of aquatic hydrogen, photodegradation of pollutants, atmospheric purification. However, due to the high recombination rate of photogenerated carrier charge and the low specific surface area of TIO _ 2 alone, the catalytic performance of TIO _ 2 is not ideal. Modification of TIO _ 2 can improve its photocatalytic activity for hydrogen production. It has always been a challenging subject with great theoretical and practical significance. By adding different co-catalysts to the surface of TIO _ 2, researchers have formed a new catalyst to capture photogenerated carrier defects in order to prolong the lifetime of photogenerated carriers. In addition, different morphologies of nanocrystalline TIO _ 2, such as nanorods, nanowires, nanotubes, etc., have been shown to generate larger specific surface areas while ensuring the rapid transfer of photogenerated electrons. In this paper, Ni S/Ti O 2 and Ni S/Ti O 2 nanotube TNTs catalysts were synthesized by solvothermal method. The hydrogen production activity of the catalysts was investigated, and the factors affecting the photocatalytic efficiency were discussed. The main work contents and conclusions are as follows: 1. Using P25, Nickel nitrate and thiourea as raw materials, nanometer Ni S/Ti O 2 photocatalyst was prepared by solvothermal method. The properties of the catalyst were tested and characterized, and the effect of the amount of Ni S on the activity of the catalyst for hydrogen production was investigated. The photocatalytic mechanism of Ni S/Ti O 2 was discussed. The results showed that Ni / Ni S/Ti O 2 catalyst had the best hydrogen production activity when the amount of Ni / Ni S was 5 wt. the amount of catalyst was 0.5 g / L, and the sacrificial reagent was methanol. The increase of photocatalytic hydrogen production activity is attributed to the synergistic effect of Ni / S and TIO _ 2 formed by Ni / 1 / Ni _ 2 / Ni _ 2 / Ni reduction potential = -0.23e / V), which is slightly lower than that of TIO _ 2 conductance band ~ (-0.26) e V ~ (-1), which is beneficial to the uplight of TIO _ 2. Electron transfer to Ni S nanoclusters) partial Ni2 is reduced to Ni elements. Metal Ni and TIO _ 2 form Schottky barrier, accelerate electron transfer to some extent and inhibit photogenerated carrier compound. Using P25 as raw material, under the strong alkali environment of 10m NaOH, the metal Ni and TIO _ 2 form Schottky barrier, and accelerate the electron transfer to some extent. Titanium dioxide nanotubes were successfully prepared by hydrothermal method, and Ni S/TNTs photocatalysts were prepared by solvothermal method. The effect of Ni S addition on photocatalytic activity was investigated and the mechanism of Ni S/TNTs photocatalytic reaction was discussed. The results showed that the TNTs prepared by alkaline hydrothermal method had one-dimensional hollow structure. The diameter range of tube is 10-15 nm, the specific surface area is 313.79 m ~ 2 g ~ (-1), about 6 times the specific surface area of P25, the addition amount of Ni S is 8 wt, the amount of catalyst is 0.5 g / L, and the sacrificial reagent is methanol, the activity of Ni S/TNTs catalyst is the best. The reason for the high catalytic activity of 7486 渭 mol h-1 g-1.Ni S/TNTs lies in the unique structure of TNTs, the large specific surface area makes the Ni S nanoclusters highly dispersed to form more reductive active sites, and the one-dimensional electron transport structure leads to the directional transport of charge of carriers and reduces the distance of photoelectron migration. Fast transfer is realized, and the recombination rate of photogenerated electron-hole pair is reduced.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O643.36;TQ116.2

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