氧化鋅基光子晶體的界面結(jié)構(gòu)設(shè)計(jì)及光電化學(xué)活性研究
發(fā)布時(shí)間：2018-10-17 14:46
【摘要】：光電化學(xué)水解產(chǎn)氫是決當(dāng)前能源與環(huán)境問題的理想技術(shù)之一,廣受國內(nèi)外學(xué)者關(guān)注。一個(gè)完整的光電化學(xué)水解產(chǎn)氫過程包括以下三個(gè)步驟:光能捕獲、光生電荷產(chǎn)生與轉(zhuǎn)移、電極界面處的氧化還原反應(yīng)。反蛋白石結(jié)構(gòu)的光子晶體一方面可以由于光子在其內(nèi)部發(fā)生的多重折射和衍射增強(qiáng)了基體對光子的捕獲,另一方面由于較短的載流子傳輸路徑,提升了光生電子和空穴的分離效率。因此,光子晶體是一種理想的光電化學(xué)水解產(chǎn)氫的納米結(jié)構(gòu)。ZnO由于環(huán)境友好、形貌可控、資源豐富,被認(rèn)為是合適的光電化學(xué)水解產(chǎn)氫的半導(dǎo)體材料。但ZnO較寬的禁帶寬度(3.2eV),限制了其在光電化學(xué)水解產(chǎn)氫方面的進(jìn)一步應(yīng)用。本論文通過界面結(jié)構(gòu)設(shè)計(jì)調(diào)控ZnO基光子晶體的光電化學(xué)活性,提高光子捕獲效率及載流子分離效率,具體研究結(jié)果有如下:1.利用層層自組裝的方法制備了三維有序堆積的聚苯乙烯(Polystyrene Sphere,PS)微球薄膜,以此為模板浸入氧化鋅前驅(qū)體溶液,通過高溫煅燒除去PS微球得到ZnO光子晶體。之后浸入鐵鹽的前驅(qū)體溶液,利用高溫條件下的固相反應(yīng)原位合成三維多孔結(jié)構(gòu)ZnO/ZnFe_2O_4光子晶體。分析了不同浸入次數(shù)對光子晶體形貌和性質(zhì)的影響,探索了最佳性能參數(shù)。利用固相轉(zhuǎn)化反應(yīng)制備的復(fù)合光子晶體界面電阻較小,光生載流子的遷移速率快,ZnO和ZnFe_2O_4能帶結(jié)構(gòu)匹配,提高了光生電子與空穴的分離效率。復(fù)合光子晶體展示出優(yōu)異的光電轉(zhuǎn)換效率,在偏壓為0.38V無助催化劑存在的條件下高達(dá)0.81%幾乎是純的氧化鋅的6倍。制備的光電極光穩(wěn)定性很好,經(jīng)過十個(gè)小時(shí)的持續(xù)光照光電流還保持了95.1%(在相同條件下衰減了 89%)。展示出了良好的光電催化性能和優(yōu)異的穩(wěn)定性。通過DFT理論計(jì)算和電化學(xué)性能分析,很好的佐證了較快的載流子動(dòng)力學(xué)促進(jìn)了 ZnO/ZnFe_2O_4反蛋白石結(jié)構(gòu)光電極性能的提升。2.以ZnO光子晶體為前驅(qū)體,通過陰陽離子交換的方法原位制備了全光譜響應(yīng)的ZnO/CdSe復(fù)合光子晶體。這種三維多孔結(jié)構(gòu)的復(fù)合光子晶體對光子的捕獲從紫外區(qū)拓寬到了近紅外區(qū),低的界面電阻提高了光生載流子的轉(zhuǎn)移與分離。在波長小于400nm光的輻射下,ZnO/CdSe復(fù)合光子晶體光電流可高達(dá)17.5 mA cm~(-2),并且樣品展現(xiàn)了令人滿意的光穩(wěn)定性。ZnO/CdSe復(fù)合光子晶體的產(chǎn)氫速率為148μmol cm~(-2)h~(-1),法拉第效率高達(dá)95%以上。相較于在相似條件下文獻(xiàn)中報(bào)道的結(jié)果,我們制備的三維多孔結(jié)構(gòu)的ZnO/CdSe復(fù)合光子晶體體現(xiàn)了優(yōu)異的競爭力。這為制備可實(shí)際應(yīng)用的高活性和穩(wěn)定性的光電極提供了新的思路。
[Abstract]:Photochemical hydrolysis of hydrogen production is one of the ideal technologies to solve the current energy and environmental problems, and has been widely concerned by scholars at home and abroad. A complete photochemical hydrolysis process for hydrogen production consists of three steps: photoenergy capture, photogenerated charge generation and transfer, and redox reaction at the electrode interface. On the one hand, photonic crystals with inverse opal structure can enhance the capture of photons due to the multiple refraction and diffraction of photons in their interior, on the other hand, because of the short carrier transmission path, The separation efficiency of photogenerated electrons and holes is improved. Therefore, photonic crystal is an ideal nano-structure of photochemical hydrolysis for hydrogen production. ZnO is considered to be a suitable semiconductor material for photochemical hydrolysis of hydrogen because of its friendly environment, controllable morphology and abundant resources. However, the wide band gap (3.2eV) of ZnO limits its further application in photochemical hydrolysis to produce hydrogen. In this paper, the photochemical activity of ZnO based photonic crystal is regulated by interface structure design, and the photonic capture efficiency and carrier separation efficiency are improved. The results are as follows: 1. Three-dimensional ordered polystyrene (Polystyrene Sphere,PS) microspheres were prepared by layer-by-layer self-assembly method, which were used as templates to immerse in zinc oxide precursor solution, and ZnO photonic crystals were obtained by calcination of PS microspheres at high temperature. After soaking in the precursor solution of iron salt, three-dimensional porous ZnO/ZnFe_2O_4 photonic crystals were synthesized in situ by solid state reaction at high temperature. The effects of different immersion times on the morphology and properties of photonic crystals were analyzed and the optimum performance parameters were explored. The interface resistance of photonic crystals prepared by solid phase conversion reaction is small, the transfer rate of photogenerated carriers is fast, the band structure of ZnO and ZnFe_2O_4 is matched, and the separation efficiency of photogenerated electrons and holes is improved. The composite photonic crystal exhibits excellent photoelectric conversion efficiency, which is almost 6 times that of pure zinc oxide at a bias voltage of 0.38 V in the presence of a helpless catalyst. The photo-electric auroral stability is very good. After 10 hours of continuous illumination, the photocurrent is kept at 95.1% (the attenuation is 89% under the same conditions). Good photocatalytic performance and excellent stability are shown. Through DFT theory calculation and electrochemical performance analysis, it is well proved that faster carrier dynamics can promote the improvement of optoelectronic pole performance of ZnO/ZnFe_2O_4 reverse opal structure. 2. Using ZnO photonic crystal as precursor, ZnO/CdSe composite photonic crystal with full spectral response was prepared in situ by anion exchange method. The photonic trapping of this three-dimensional porous composite photonic crystal extends from the ultraviolet region to the near infrared region, and the low interfacial resistance increases the transfer and separation of photogenerated carriers. The photocurrent of ZnO/CdSe composite photonic crystal can reach 17.5 mA cm~ (-2) under the radiation of wavelength less than 400nm, and the sample shows satisfactory photostability. The hydrogen production rate of ZnO/CdSe composite photonic crystal is 148 渭 mol cm~ (-2) h ~ (-1), and the Faraday efficiency is over 95%. Compared with the results reported in the literature under similar conditions, the ZnO/CdSe composite photonic crystals with three dimensional porous structures exhibit excellent competitiveness. This provides a new idea for the preparation of highly active and stable photoelectrodes which can be applied in practice.
【學(xué)位授予單位】：安徽大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O734
本文編號：2277016
[Abstract]:Photochemical hydrolysis of hydrogen production is one of the ideal technologies to solve the current energy and environmental problems, and has been widely concerned by scholars at home and abroad. A complete photochemical hydrolysis process for hydrogen production consists of three steps: photoenergy capture, photogenerated charge generation and transfer, and redox reaction at the electrode interface. On the one hand, photonic crystals with inverse opal structure can enhance the capture of photons due to the multiple refraction and diffraction of photons in their interior, on the other hand, because of the short carrier transmission path, The separation efficiency of photogenerated electrons and holes is improved. Therefore, photonic crystal is an ideal nano-structure of photochemical hydrolysis for hydrogen production. ZnO is considered to be a suitable semiconductor material for photochemical hydrolysis of hydrogen because of its friendly environment, controllable morphology and abundant resources. However, the wide band gap (3.2eV) of ZnO limits its further application in photochemical hydrolysis to produce hydrogen. In this paper, the photochemical activity of ZnO based photonic crystal is regulated by interface structure design, and the photonic capture efficiency and carrier separation efficiency are improved. The results are as follows: 1. Three-dimensional ordered polystyrene (Polystyrene Sphere,PS) microspheres were prepared by layer-by-layer self-assembly method, which were used as templates to immerse in zinc oxide precursor solution, and ZnO photonic crystals were obtained by calcination of PS microspheres at high temperature. After soaking in the precursor solution of iron salt, three-dimensional porous ZnO/ZnFe_2O_4 photonic crystals were synthesized in situ by solid state reaction at high temperature. The effects of different immersion times on the morphology and properties of photonic crystals were analyzed and the optimum performance parameters were explored. The interface resistance of photonic crystals prepared by solid phase conversion reaction is small, the transfer rate of photogenerated carriers is fast, the band structure of ZnO and ZnFe_2O_4 is matched, and the separation efficiency of photogenerated electrons and holes is improved. The composite photonic crystal exhibits excellent photoelectric conversion efficiency, which is almost 6 times that of pure zinc oxide at a bias voltage of 0.38 V in the presence of a helpless catalyst. The photo-electric auroral stability is very good. After 10 hours of continuous illumination, the photocurrent is kept at 95.1% (the attenuation is 89% under the same conditions). Good photocatalytic performance and excellent stability are shown. Through DFT theory calculation and electrochemical performance analysis, it is well proved that faster carrier dynamics can promote the improvement of optoelectronic pole performance of ZnO/ZnFe_2O_4 reverse opal structure. 2. Using ZnO photonic crystal as precursor, ZnO/CdSe composite photonic crystal with full spectral response was prepared in situ by anion exchange method. The photonic trapping of this three-dimensional porous composite photonic crystal extends from the ultraviolet region to the near infrared region, and the low interfacial resistance increases the transfer and separation of photogenerated carriers. The photocurrent of ZnO/CdSe composite photonic crystal can reach 17.5 mA cm~ (-2) under the radiation of wavelength less than 400nm, and the sample shows satisfactory photostability. The hydrogen production rate of ZnO/CdSe composite photonic crystal is 148 渭 mol cm~ (-2) h ~ (-1), and the Faraday efficiency is over 95%. Compared with the results reported in the literature under similar conditions, the ZnO/CdSe composite photonic crystals with three dimensional porous structures exhibit excellent competitiveness. This provides a new idea for the preparation of highly active and stable photoelectrodes which can be applied in practice.
【學(xué)位授予單位】：安徽大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O734
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 李珩;王京霞;王榮明;宋延林;;三維膠體光子晶體對光的調(diào)控與應(yīng)用研究[J];化學(xué)進(jìn)展;2011年06期
，本文編號：2277016
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