分子催化劑修飾的釩酸鉍光陽極的制備與光電性能研究
發(fā)布時間：2018-10-05 16:19
【摘要】：利用太陽能驅(qū)動水分解生產(chǎn)清潔化學(xué)燃料-氫氣,被認(rèn)為是減輕化石燃料燃燒引起的環(huán)境問題,滿足全球日益增長的能源需求的有效途徑。在人工光合作用體系中,水分解反應(yīng)是提供質(zhì)子和電子的關(guān)鍵步驟,是制約太陽能轉(zhuǎn)化的瓶頸。在水分解反應(yīng)中影響太陽能燃料合成效率的主要限制因素包括:ⅰ)光吸收,ⅱ)電荷分離和運(yùn)輸, ⅲ)表面化學(xué)反應(yīng)。在光敏半導(dǎo)體上負(fù)載可以改善電子電荷分離或可以充當(dāng)空穴受體的助催化劑是解決這些難題的有效手段。本文以價格低廉的鈷金屬為原料,合成了帶乙烯基的鈷立方烷水氧化分子催化劑Col,將Col在FTO和BiVO_4上以電化學(xué)聚合的方式負(fù)載,制備了poly-1/FTO復(fù)合陽極和poly-1/BiVO_4光陽極。對于poly-1/FTO電極來說,在外加電壓為1.2VvsAg/AgCl時,電流密度可達(dá)到4mA/cm~2。經(jīng)過長時間電解后,依然有將近2 mA/cm~2的電流密度存在。電極的法拉第效率可以達(dá)到84.8%。對于 poly-1/BiVO_4 光陽極,在 0.6 V vs Ag/AgCl 偏壓和 100 mW/cm~2 光照下,poly-1/BiVO_4光陽極比BiVO_4光電流密度提高了 8倍。法拉第效率由BiVO_4的31.4 %提高至59.8 %。入射單色光子-電子轉(zhuǎn)化效率(IPCE)由BiVO_4的5 %提高至了 23 %,光陽極的空穴注入效率由BiVO_4的20 %以下提高至了 80 %以上,而poly-1/BiVO_4相對于BiVO_4的電荷分離效率在1.23 V vs RHE處接近90 %。本文還改進(jìn)方法制備了 BiVO_4半導(dǎo)體材料,并制備了 AuNPs修飾的納米多孔BiVO_4光電陽極,利用AuNPs的等離子體效應(yīng)來增強(qiáng)復(fù)合電極的光響應(yīng)。將制備的AuNPs/BiVO_4電極進(jìn)行光電化學(xué)測試,測試結(jié)果表明,與單獨的BiVO_4相比,AuNPs/BiVO_4復(fù)合電極光催化分解水的光電流有明顯提高,說明金的等離子體效應(yīng)有助于BiVO_4和金的電荷傳輸。合成了巰基修飾的聯(lián)吡啶釕基分子催化劑Ru1,通過AuNPs和巰基之間的化學(xué)吸附作用,將催化劑負(fù)載于AuNPs/BiVO_4電極表面。對Ru1/AuNPs/BiVO_4陽極的光催化水氧化的性能進(jìn)行了深入的研究,在100 mW/cm~2光照條件下,外加0.62 V vs Ag/AgCl偏壓,Ru1/AuNPs/BiVO_4光陽極電流密度可達(dá)2 mA/cm~2,比BiVO_4高4倍,比AuNPs/BiVO_4的光電流高1.5倍,并且測試時間內(nèi)無明顯的電流下降,得到了相對穩(wěn)定的恒定電流。
[Abstract]:The use of solar energy to drive water decomposition to produce clean chemical fuel-hydrogen is considered to be an effective way to alleviate the environmental problems caused by fossil fuel combustion and to meet the increasing global energy demand. In artificial photosynthesis, water decomposition is the key step to provide protons and electrons, and is the bottleneck of solar energy conversion. The main factors limiting the efficiency of solar fuel synthesis in water decomposition include: I) light absorption, II) charge separation and transport, and III) surface chemical reaction. Loading on Guang Min semiconductor can improve the separation of electron charge or act as a catalyst for hole receptor is an effective way to solve these problems. In this paper, the low cost cobalt metal was used as the raw material to prepare poly-1/FTO composite anode and poly-1/BiVO_4 photoanode by electrochemical polymerization of Col on FTO and BiVO_4 supported by Col, a molecular catalyst of cobalt cubic alkane water oxidation with vinyl group. For the poly-1/FTO electrode, the current density can reach 4 Ma / cm ~ (2) when the applied voltage is 1.2VvsAg/AgCl. After a long period of electrolysis, there is still a current density of nearly 2 mA/cm~2. The Faraday efficiency of the electrode can reach 84.8. For the poly-1/BiVO_4 photoanode, the photocurrent density of the poly-1 / Bivos _ 4 photoanode is 8 times higher than that of the BiVO_4 photoanode under 0. 6 V vs Ag/AgCl bias and 100 mW/cm~2 illumination. Faraday efficiency increased from 31.4% of BiVO_4 to 59.8%. The incident monochromatic photon electron conversion efficiency (IPCE) is increased from 5% of BiVO_4 to 23%, the hole injection efficiency of photoanode is increased from less than 20% of BiVO_4 to more than 80%, and the charge separation efficiency of poly-1/BiVO_4 relative to BiVO_4 is close to 90% at 1.23 V vs RHE. In this paper, BiVO_4 semiconductor materials and AuNPs modified nano-porous BiVO_4 photoanode were prepared. The photoresponse of the composite electrode was enhanced by using the plasma effect of AuNPs. The photochemical test of the prepared AuNPs/BiVO_4 electrode shows that the photocatalytic photocurrent of the au / ANPs / BiVO _ 4 composite electrode is significantly higher than that of the single BiVO_4 electrode, indicating that the plasma effect of gold is helpful to the charge transport of BiVO_4 and gold. Mercapto modified bipyridine ruthenium based catalyst Ru1, was synthesized by chemisorption between AuNPs and sulfhydryl. The catalyst was supported on the surface of AuNPs/BiVO_4 electrode. The photocatalytic water oxidation of Ru1/AuNPs/BiVO_4 anode was studied. Under 100 mW/cm~2 illumination, the current density of the photoanode was 4 times higher than that of BiVO_4 and 1.5 times higher than that of AuNPs/BiVO_4 under 0.62 V vs Ag/AgCl bias voltage Ru1 / AuNPs / BiVO4. And there is no obvious current drop in the test time, and a relatively stable constant current is obtained.
【學(xué)位授予單位】：遼寧大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36;O646.5
[Abstract]:The use of solar energy to drive water decomposition to produce clean chemical fuel-hydrogen is considered to be an effective way to alleviate the environmental problems caused by fossil fuel combustion and to meet the increasing global energy demand. In artificial photosynthesis, water decomposition is the key step to provide protons and electrons, and is the bottleneck of solar energy conversion. The main factors limiting the efficiency of solar fuel synthesis in water decomposition include: I) light absorption, II) charge separation and transport, and III) surface chemical reaction. Loading on Guang Min semiconductor can improve the separation of electron charge or act as a catalyst for hole receptor is an effective way to solve these problems. In this paper, the low cost cobalt metal was used as the raw material to prepare poly-1/FTO composite anode and poly-1/BiVO_4 photoanode by electrochemical polymerization of Col on FTO and BiVO_4 supported by Col, a molecular catalyst of cobalt cubic alkane water oxidation with vinyl group. For the poly-1/FTO electrode, the current density can reach 4 Ma / cm ~ (2) when the applied voltage is 1.2VvsAg/AgCl. After a long period of electrolysis, there is still a current density of nearly 2 mA/cm~2. The Faraday efficiency of the electrode can reach 84.8. For the poly-1/BiVO_4 photoanode, the photocurrent density of the poly-1 / Bivos _ 4 photoanode is 8 times higher than that of the BiVO_4 photoanode under 0. 6 V vs Ag/AgCl bias and 100 mW/cm~2 illumination. Faraday efficiency increased from 31.4% of BiVO_4 to 59.8%. The incident monochromatic photon electron conversion efficiency (IPCE) is increased from 5% of BiVO_4 to 23%, the hole injection efficiency of photoanode is increased from less than 20% of BiVO_4 to more than 80%, and the charge separation efficiency of poly-1/BiVO_4 relative to BiVO_4 is close to 90% at 1.23 V vs RHE. In this paper, BiVO_4 semiconductor materials and AuNPs modified nano-porous BiVO_4 photoanode were prepared. The photoresponse of the composite electrode was enhanced by using the plasma effect of AuNPs. The photochemical test of the prepared AuNPs/BiVO_4 electrode shows that the photocatalytic photocurrent of the au / ANPs / BiVO _ 4 composite electrode is significantly higher than that of the single BiVO_4 electrode, indicating that the plasma effect of gold is helpful to the charge transport of BiVO_4 and gold. Mercapto modified bipyridine ruthenium based catalyst Ru1, was synthesized by chemisorption between AuNPs and sulfhydryl. The catalyst was supported on the surface of AuNPs/BiVO_4 electrode. The photocatalytic water oxidation of Ru1/AuNPs/BiVO_4 anode was studied. Under 100 mW/cm~2 illumination, the current density of the photoanode was 4 times higher than that of BiVO_4 and 1.5 times higher than that of AuNPs/BiVO_4 under 0.62 V vs Ag/AgCl bias voltage Ru1 / AuNPs / BiVO4. And there is no obvious current drop in the test time, and a relatively stable constant current is obtained.
【學(xué)位授予單位】：遼寧大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36;O646.5
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