染料敏化光催化制氢体系中的溶剂效应和铜基催化剂的研究

发布时间：2018-10-09 16:49

【摘要】：本论文以光催化制氢体系中敏化剂和催化剂上的电子转移为研究的切入点,通过引入二甲基亚砜(DMSO)有效地抑制了激发态虎红(RB*)的非辐射过程并延长了激发态RB*的荧光寿命。同时,通过原位光还原Cu_2O/TiO_2制备了Cu/Cu_2O/Cu/TiO_2催化剂,对氧化铜和氧化亚铜作为光催化剂的制氢机理进行了研究,发现夹层金属铜在该催化剂中传导电子的重要作用。本论文主要内容如下:1.DMSO对抑制激发态RB~*非辐射过程和提高光催化制氢效率作用的研究在RB敏化Pt催化制氢体系中,引入少量DMSO能够有效地抑制质子诱发引起的激发态RB~(ˉ*)非辐射过程,从而提高光催化制氢效率。在可见光激发下,激发态RB*很容易跟水分子发生分子间质子转移形成激发态RB~(ˉ*),这种激发态RB~(ˉ*)很容易与H+结合而被猝灭,造成激发态RB~(ˉ*)的光生电子损失从而导致制氢效率下降。研究发现少量DMSO加入该反应体系,减弱了水分子与激发态RB~*之间的氢键作用,同时抑制了激发态RB*与水分子间的质子转移,进而降低了激发态RB~(ˉ*)的非辐射过程。制氢测试结果表明DMSO的引入使RB敏化Pt催化体系的制氢量在120 min内达到1410.7μmol,是没有DMSO引入的4.48倍。在550nm处,RB敏化Pt催化剂制氢体系达到最大的制氢量子效率,其值为44.3%。2.Cu/Cu_2O/Cu/TiO_2催化剂中夹层金属铜对可见光催化制氢的重要作用通过原位光还原Cu_2O/TiO_2制备了Cu/Cu_2O/Cu/TiO_2夹层结构的光催化剂。研究发现夹层金属Cu在Cu/Cu_2O/Cu/TiO_2催化剂中起着非常重要的作用,夹层金属Cu在制氢过程中为TiO_2导带上的电子向Cu_2O的转移提供了便捷的通道,使得光电子的寿命得到极大延长。此外,通过调节Cu/Cu_2O/Cu/TiO_2催化剂中的夹层金属Cu与Cu_2O的摩尔比可显著改善催化剂的制氢活性,当夹层金属Cu和Cu_2O的摩尔比是0.99时,Cu/Cu_2O/Cu/TiO_2催化剂表现出最高的瞬态光电流和较长的荧光寿命(0.365 ns)。在相同条件下,Cu/Cu_2O/Cu/TiO_2催化剂的制氢活性是Cu/TiO_2催化剂的三倍,并且具有较好的制氢稳定性。
[Abstract]:In this paper, the electron transfer between sensitizer and catalyst in photocatalytic hydrogen production system is taken as the starting point. By introducing dimethyl sulfoxide (DMSO), the non-radiation process of excited tiger red (RB*) is effectively suppressed and the fluorescence lifetime of excited RB* is prolonged. At the same time, Cu/Cu_2O/Cu/TiO_2 catalyst was prepared by in situ photoreduction of Cu_2O/TiO_2. The hydrogen production mechanism of copper oxide and cuprous oxide as photocatalysts was studied. The important role of interlayer metal copper in conducting electrons in the catalyst was found. The main contents of this thesis are as follows: 1. The effect of DMSO on the inhibition of excited RB~* nonradiative process and the improvement of photocatalytic hydrogen production efficiency in RB sensitized Pt catalytic hydrogen production system. The introduction of a small amount of DMSO can effectively suppress the non-radiative process of proton induced excited state RB~ (RB~ *) and thus improve the efficiency of photocatalytic hydrogen production. Excited by visible light, excited state RB* can easily transfer with water molecule to form excited state RB~ (RB~ *). This excited state RB~ (RB~ *) is easily quenched with H, resulting in photoelectron loss of excited state RB~ (RB~ *), which leads to the decrease of hydrogen production efficiency. It is found that the addition of a small amount of DMSO to the reaction system weakens the hydrogen bond between the water molecule and the excited RB~*, and at the same time inhibits the proton transfer between the excited RB* and the water molecule, thus reducing the non-radiative process of the excited RB~. The hydrogen production test results show that the hydrogen production of RB sensitized Pt catalyst system can reach 1410.7 渭 mol, within 120 min with the introduction of DMSO, which is 4.48 times as high as that without DMSO. The hydrogen production system of RB sensitized Pt catalyst at 550nm achieves the maximum hydrogen production quantum efficiency. The value of the interlayer metal copper in the 44.3%.2.Cu/Cu_2O/Cu/TiO_2 catalyst plays an important role in the visible light catalytic hydrogen production. The Cu/Cu_2O/Cu/TiO_2 interlayer photocatalyst was prepared by in situ photoreduction of Cu_2O/TiO_2. It is found that interlayer metal Cu plays a very important role in the Cu/Cu_2O/Cu/TiO_2 catalyst. The interlayer metal Cu provides a convenient channel for the transfer of electrons from TiO_2 conduction band to Cu_2O in the process of hydrogen production, which greatly prolongs the lifetime of photoelectrons. In addition, by adjusting the molar ratio of interlayer metal Cu to Cu_2O in Cu/Cu_2O/Cu/TiO_2 catalyst, the hydrogen production activity of the catalyst can be significantly improved. When the molar ratio of interlayer metal Cu to Cu_2O is 0.99, the catalyst Cu / Cu _ 2O / Cu / TIO _ 2 exhibits the highest transient photocurrent and longer fluorescence lifetime (0.365 ns). Under the same conditions, the catalytic activity of Cu- / TiO-2 catalyst is three times as high as that of Cu/TiO_2 catalyst, and the catalyst has better hydrogen production stability.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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