【摘要】：通過半導體光催化還原水制氫,將太陽能轉(zhuǎn)化為清潔、可再生的氫能,已經(jīng)成為目前光催化領域的研究熱點。鈮酸鉀是一種穩(wěn)定、廉價,形貌可調(diào)、易于被改性的半導體,在光催化還原水制氫和傳感等領域有潛在的應用前景。本文首先以還原氧化石墨烯替代貴金屬Pt作為助催化劑,與不同形貌的鈮酸鉀組裝制備得到了多種光催化劑,進而研究其在光催化還原水制氫中的活性、穩(wěn)定性及電子轉(zhuǎn)移機制。其次,組裝了層數(shù)可控、有序的鈮酸鉀納米片/Ag20復合膜,研究其對低濃度結(jié)晶紫的拉曼響應及作用機理。主要研究內(nèi)容如下：通過在鈮酸鉀納米片卷曲過程中插入還原氧化石墨烯(RGO),制備得到了一種新型的RGO/鈮酸鉀復合納米軸。通過XRD、TEM、固體紫外-可見漫反射光譜表征了鈮酸鉀/RGO復合納米軸的結(jié)構(gòu)、形貌與光學特性。對比研究了鈮酸鉀/RGO復合納米軸在紫外光照射下的光催化還原水制氫活性。研究結(jié)果表明：復合少量的RGO(2%)即能使鈮酸鉀納米軸的光催化制氫量提高3.1倍,而且性能穩(wěn)定。通過熒光光譜和交流阻抗圖譜說明RGO的引入能有效提高鈮酸鉀納米軸的光生電子和空穴的分離效率,這是RGO/鈮酸鉀復合納米軸具有較高光催化制氫活性的主要原因。在室溫下混合、攪拌還原氧化石墨烯和鈮酸鉀微球制備得到了一種核殼結(jié)構(gòu)的還原氧化石墨烯／鈮酸鉀復合微球光催化劑。通過XRD、SEM、固體紫外-可見漫反射光譜、熒光光譜和交流阻抗圖譜等手段研究了所得產(chǎn)物的組成、形貌與電子轉(zhuǎn)移。由于還原氧化石墨烯作為助催化劑,能夠及時將光生電子轉(zhuǎn)移,從而避免了與空穴復合,所以,還原氧化石墨烯／鈮酸鉀復合微球在紫外光照射下表現(xiàn)出比純鈮酸鉀微球和P25 TiO2更高的還原水制氫活性。此外,我們研究了氧化石墨烯-鈮酸鉀復合微球在紫外光照射下的還原水制氫的循環(huán)使用穩(wěn)定性,結(jié)果表明,還原氧化石墨烯／鈮酸鉀復合微球經(jīng)六次循環(huán)使用后其還原水制氫活性基本不變,說明還原氧化石墨烯／鈮酸鉀復合微球是一種廉價、易得、光催化制氫活性高、穩(wěn)定的光催化劑。通過層層自組裝技術并結(jié)合紫外光原位還原法制備了一種形貌規(guī)整、有序的鈮酸鉀納米片/氧化銀復合膜。通過XRD、SEM、XPS等多種手段對復合膜的組成、結(jié)晶性和形貌等進行了表征。以鈮酸鉀納米片／納米氧化銀復合膜為活性基底,通過表面增強拉曼散射光譜研究了其對低濃度結(jié)晶紫的檢測。研究結(jié)果顯示,鈮酸鉀納米片／納米氧化銀復合膜能快速、高效地檢測低濃度的結(jié)晶紫,而復合膜中納米氧化銀與鈮酸鉀納米片之間快速的電子轉(zhuǎn)移是其實現(xiàn)低濃度結(jié)晶紫檢測的關鍵。
[Abstract]:The conversion of solar energy to clean and renewable hydrogen energy by photocatalytic reduction of water to hydrogen has become a hot spot in the field of photocatalysis. Potassium niobate is a stable, cheap, adjustable and easily modified semiconductor, which has potential applications in photocatalytic reduction of water for hydrogen production and sensing. In this paper, a variety of photocatalysts were prepared by using reductive graphene instead of noble metal Pt as co-catalysts and assembled with potassium niobate with different morphologies, and their activity in photocatalytic reduction of water for hydrogen production was studied. Stability and electron transfer mechanism. Secondly, the layered and ordered potassium niobate / Ag20 composite films were assembled and their Raman response to low concentration crystal violet was studied. The main research contents are as follows: a novel RGO/ potassium niobate composite nano-axis was prepared by inserting reduced graphene oxide (RGO),) in the crimp process of potassium niobate nanoparticles. The structure, morphology and optical properties of potassium niobate / RGO composite nano-axis were characterized by XRD,TEM, solid-state UV-Vis diffuse reflectance spectroscopy. The photocatalytic reduction activity of potassium niobate / RGO nanoaxis for hydrogen production from water under UV irradiation was studied. The results show that the photocatalytic hydrogen production of potassium niobate nanoaxis can be increased by 3.1 times with a small amount of RGO (2%), and the performance is stable. Fluorescence spectra and AC impedance spectra show that the introduction of RGO can effectively improve the separation efficiency of photogenerated electrons and holes in the potassium niobate nanoaxis, which is the main reason for the high photocatalytic activity of RGO/ potassium niobate nanoaxis. A core-shell structure photocatalyst of reduced graphene / potassium niobate composite microspheres was prepared by mixing graphene oxide and potassium niobate microspheres at room temperature. The composition, morphology and electron transfer of the products were studied by means of XRD,SEM, solid-state UV-Vis diffuse reflectance spectroscopy, fluorescence spectra and AC impedance spectroscopy. Because the reduced graphene oxide acts as a co-catalyst, it can transfer photogenerated electrons in time, thus avoiding the recombination with the hole, so, The redox graphene / potassium niobate composite microspheres exhibit higher hydrogen production activity under UV irradiation than pure potassium niobate microspheres and P25 TiO2. In addition, the stability of hydrogen production by reducing water with graphene oxide and potassium niobate composite microspheres under UV irradiation was studied. The redox graphene / potassium niobate composite microspheres had almost no change in hydrogen production activity after six cycles, which indicated that the reduced graphene / potassium niobate composite microspheres were cheap, easy to obtain and high in photocatalytic hydrogen production. A stable photocatalyst. A structured and ordered potassium niobate / silver oxide composite film was prepared by layer-by-layer self-assembly technique and UV in-situ reduction method. The composition, crystallinity and morphology of the composite films were characterized by XRD,SEM,XPS. The determination of low concentration crystal violet was studied by surface-enhanced Raman scattering with potassium niobate / nano-silver oxide composite film as active substrate. The results show that the potassium niobate nanochip / nano-silver oxide composite film can be used to detect crystal violet with low concentration quickly and efficiently. The rapid electron transfer between nano-silver oxide and potassium niobate nanoparticles in the composite film is the key to the detection of low concentration crystal violet.
【學位授予單位】：上海應用技術學院
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：O643.36;TQ116.2

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