發(fā)布時間：2018-04-21 03:14

  本文選題：二維納米材料 + 光催化��； 參考：《中國科學技術大學》2015年博士論文

【摘要】：實現(xiàn)光生載流子的最大化分離是提高人工太陽能轉換效率的關鍵。本論文基于納米固體化學原理,選擇結構清晰的超薄二維納米片為模型,結合時間分辨光譜、自旋捕獲等原位表征手段,來深入理解表面微結構、有機-無機界面、小分子有機物等對半導體中光生載流子分離和遷移的影響,為設計和構筑高效的人工光催化體系提供理論支持。本論文的研究內容包括以下幾個方面： 1、我們提出低維化是抑制半導體光生載流子復合的有效途徑,尤其是二維納米材料,它具有高比表面積,短載流子擴散距離,強光吸收等優(yōu)勢；同時其優(yōu)異的力學性能滿足了人們對柔性、便攜式器件的需求,因此是柔性光電器件的理想載體。本工作發(fā)展了自犧牲模板法來合成非層狀四方黃銅礦結構的CuInSe2超薄納米片,高度各向異性的CuSe六方片不僅是CuInSe2形貌上的模板,而且作為結構模板用于控制CuInSe2納米片的厚度。CuSe的(001)晶面和CuInSe2(112)晶面的原子排布匹配,為CuInSe2平行(112)晶面生長提供驅動力：同時反應過程中,在CuSe[001]方向上In取代部分Cu引入應力,使準層狀結構CuSe的Se-Se鍵斷裂,從而抑制CuInSe2納米片沿此方向生長,實現(xiàn)對CuInSe2納米片厚度的控制。CuInSe2超薄納米片的成功合成充分驗證了自犧牲模板法在控制納米結構形貌上的優(yōu)勢。CuInSe2超薄納米片-P3HT的能級交錯,獨特的界面結構有效促進載流子的分離,因此兩者構建的雜化柔性光探測器表現(xiàn)出優(yōu)異的光響應性能,開關比高達兩個量級,響應時間達到1.7s,同時表現(xiàn)出優(yōu)異的抗彎折性能。 2、我們提出結構明確的超薄納米片是研究表面缺陷與材料光催化性能的理想載體。以K4Nb6O17超薄納米片為例,我們通過可控還原過程引入表面氧空位,使其帶隙降低0.2eV,從而促進了光吸收；同時,表面氧空位捕獲光生電子,促進載流子的高效分離和利用。實驗結果證實：含表面氧空位的K4Nb6O17超薄納米片展示出大幅提高的光催化性能,產氫速率達到1661μmol·g-1·h-1,與無氧空位的塊材相比提高了20倍,而與無氧空位的超薄納米片相比則有6倍的提高。同時本工作中氧空位空間分布對光催化性能影響的研究解決了長期以來氧空位在光催化過程中的角色爭議,體相氧空位是載流子復合的中心,而表面氧空位則促進載流子的高效分離,抑制電子-空穴復合。氧空位分布調控策略不僅為深入理解氧空位對光催化性能的影響提供新思路,而且為利用調控半導體缺陷來設計高效產氫催化劑打開切實可行的途徑。 3、我們提出水溶性小分子助催化劑策略來加速光生空穴的轉移�？赡嫜趸�原電對TFA·/TFA-使三氟乙酸(TFA)成為優(yōu)異的分子助催化劑,為光生電子-空穴對提供了進一步的分離路徑,從而促進光催化產氫。原位電子自旋共振(ESR)及能級對應關系顯示出K4Nb6O17價帶的光致空穴易與吸附的TFA陰離子反應產生TFA自由基。同時生成的高活性自由基轉移空穴至甲醇,從而抑制了電子-空穴復合。此外,超快吸收光譜及穩(wěn)態(tài)和時間分辨的發(fā)光光譜確認了高效的電荷分離是光催化性能大幅提高的主要因素。均相分子助催化劑不受催化劑與反應物接觸面積的限制,為催化提供足夠的反應位點,因此為發(fā)展高效光催化體系提供了機遇。
[Abstract]:Realizing the maximum separation of optical carrier is the key to improve the efficiency of the conversion of artificial solar energy. Based on the principle of nano solid chemistry, this paper selects the ultrathin two-dimensional nanoscale with clear structure as the model. It combines the time resolved spectrum and the spin capture in situ to understand the surface microstructures, the organic inorganic interface and the small molecules. The effects of aircraft on the separation and migration of photogenerated carriers in semiconductors provide theoretical support for the design and construction of a highly efficient artificial photocatalytic system. The contents of this paper include the following aspects:
1, we propose that low dimension is an effective way to suppress semiconductor optical carrier recombination, especially two dimensional nanomaterials. It has the advantages of high surface area, short carrier diffusion distance, strong light absorption and so on. At the same time, its excellent mechanical properties meet the needs of flexible and portable devices. Therefore, it is an ideal load of flexible optoelectronic devices. This work has developed a self sacrificial template method for the synthesis of CuInSe2 ultra-thin nanometers of non layered Quartet chalcopyrite structure. The highly anisotropic CuSe six slice is not only a template on the morphology of the CuInSe2, but also as a structural template for controlling the atomic arrangement of (001) and CuInSe2 (112) crystal surfaces of the thickness of CuInSe2 nanoscale,.CuSe. To provide driving force for CuInSe2 parallel (112) crystal surface growth: at the same time, in the course of the reaction, the In substitution of partial Cu in the direction of CuSe[001] leads to the crack of the Se-Se bond of the quasi layered structure CuSe, thereby inhibiting the growth of the CuInSe2 nanoscale along this direction, and realizing the successful synthesis of the.CuInSe2 ultra-thin nanoscale with the thickness of CuInSe2 nanoscale. The advantages of self sacrificing template method in controlling the nanostructure morphology are interlaced, and the unique interface structure can effectively promote the separation of carriers. Therefore, the hybrid flexible photodetectors have excellent optical response performance. The switch ratio is up to two orders, the response time is up to 1.7s, and the table is at the same time. Excellent bending resistance.
2, we propose that ultrathin nanoscale is an ideal carrier for the study of surface defects and photocatalytic properties of materials. Taking K4Nb6O17 ultra-thin nanoscale as an example, we introduce surface oxygen vacancies by controlled reduction process to reduce the band gap of 0.2eV and thus promote optical absorption; at the same time, surface oxygen vacancies capture photoelectrons to promote carriers. The experimental results show that the K4Nb6O17 ultra-thin nanoscale containing the surface oxygen vacancy shows a significant enhancement in the photocatalytic performance, the hydrogen production rate reaches 1661 Mu mol. G-1. H-1, which is 20 times higher than that of the non oxygen vacant bulk, while the oxygen vacancy is 6 times higher than that of the ultra-thin nanoscale without oxygen vacancy. The study of the influence of spatial distribution on the photocatalytic activity has solved the role controversy in the photocatalytic process for a long time. The oxygen vacancy of the bulk is the center of the carrier recombination, while the surface oxygen vacancy promotes the efficient separation of the carrier and inhibits the recombination of the electron hole. The effect of catalytic performance provides a new idea and opens a feasible way to design efficient hydrogen production catalyst by controlling semiconductor defects.
3, we propose a water-soluble small molecular cocatalyst strategy to accelerate the transfer of photogenerated holes. Reversible oxidation-reduction electricity makes TFA. /TFA- an excellent molecular cocatalyst for three FLUOROACETIC acid (TFA), which provides a further separation path for photoelectron hole pairs, thus promoting the photocatalytic hydrogen production. In situ electron spin resonance (ESR) and energy level pairs The relationship shows that the photoinduced cavitation of the K4Nb6O17 valence band is easy to react with the adsorbed TFA anion to produce TFA radical. Meanwhile, the high active free radical transfer cavitation to methanol, which inhibits the electron hole recombination. In addition, the ultra fast absorption spectrum and the steady and time resolved luminescence spectra confirm that the efficient charge separation is photocatalytic. The main factor that can be greatly improved. The homogeneous molecular cocatalyst is not limited by the contact area between the catalyst and the reactant, and provides sufficient reaction sites for the catalysis, thus providing an opportunity for the development of the high effective photocatalytic system.

【學位授予單位】：中國科學技術大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TK511;TB383.1

【共引文獻】

相關期刊論文 前10條

1 羅水源;何杰;趙俊斌;;層狀鈮酸鹽M_xNb_6O_(17)(M=K,Fe,Ni)的合成及對甲硫醇的吸附與光催化性能研究[J];廣東化工;2009年06期

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本文編號：1780680