微波合成二硫化錫作為光催化 二氧化碳還原之研究
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2016
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Abstract
本研究使用連續進樣式二氧化碳光催化反應系統，以鹵素燈作為模擬太陽光光源激發二硫化錫光觸媒，以固-氣相的催化反應將二氧化碳還原成具有經濟價值的碳氫化合物，並原位進樣反應器中的氣體至氣相層析儀/火燄離子化偵測器，再利用與量測方式相同之連續式檢量線，即可及時量測反應效率並轉換成量子效率。
為了有效地縮短加熱時間並且精準地控制合成條件，本篇合成之二硫化錫光催化觸媒是利用程式控制之微波加熱法合成，借助微電腦以及反應器內溫度的即時回饋控制，此合成方法擁有優異的再現性。
同時本研究以拉曼光譜儀與X-光繞射儀進行結晶性的分析，利用掃描式電子顯微鏡作材料微結構鑑定，將X-光吸收光譜做線性疊加進行材料組成分析，最後將表面功函數量測系統與紫外光-可見光吸收光譜結合建立能帶資訊，探討能帶與二氧化碳光催化之關係，以此探討不同溶劑、合成時間對二硫化錫粒子的影響。
本篇利用乙二醇、乙醇或是去離子水作為溶劑，改變不同的反應時間以及SDS的添加量，以求最高的量子效率。最後發現以去離子水添加1 %莫耳百分比的SDS反應60分鐘時，成功地利用光催化反應將二氧化碳還原成八個電子轉移的乙醛，同時計算其量子效率達到了0.028 %，是市售二硫化錫量子效率0.0011 %的25倍。
With a photocatalysis system for CO2 reduction reactions linked to a halogen lamp solar source, we continuously collected highly valuable organic products in-situ by using tin disulfide photocatalysis in solid - gas phase reaction with Gas chromatography/Flame ionized detector (GC/FID). Then, using a newly developed calibration curve for the real time system, we converted the signal to measure the quantum efficiency (QE). In this study, we shortened the reaction time and maintained precise control of our system conditions by using a programmable microwave-assisted synthesis system for tin disulfide particles synthetization; thusly, we could reproduce high quality samples easily. Six major techniques were used to characterize the particles: Raman spectroscopy and X-ray diffraction spectroscopy were used for crystallinity analysis, a Scanning Electron Microscopy for microstructure characterization, X-ray absorption spectroscopy from NSRRC, to quantify different components by linear combination of standard compounds, and photo-electron spectroscopy in air coupled with UV-Visible absorption spectroscopy to find the relationship between band position and photocatalytic reactivity. We tried optimizing efficiency of the tin disulfide by: sampling different solvents (ethylene glycol, ethanol, and deionized water ) in the microwave reaction, testing different reaction times (5 min - 120 min), and altering the concentration of SDS (0-2000%). We found that by synthesizing tin disulfide in deionized water with 1% SDS for 1 hour we achieved a QE of 0.028%, which is 25 times better than the commercial tin disulfide. Furthermore, the CO2 reduction reaction resulted in the formation of acetaldehyde, implying eight electrons transferred. In total, we found a new process for the synthesis of tin disulfide that demonstrates a significant enhancement to the reduction activity of carbon dioxide.
With a photocatalysis system for CO2 reduction reactions linked to a halogen lamp solar source, we continuously collected highly valuable organic products in-situ by using tin disulfide photocatalysis in solid - gas phase reaction with Gas chromatography/Flame ionized detector (GC/FID). Then, using a newly developed calibration curve for the real time system, we converted the signal to measure the quantum efficiency (QE). In this study, we shortened the reaction time and maintained precise control of our system conditions by using a programmable microwave-assisted synthesis system for tin disulfide particles synthetization; thusly, we could reproduce high quality samples easily. Six major techniques were used to characterize the particles: Raman spectroscopy and X-ray diffraction spectroscopy were used for crystallinity analysis, a Scanning Electron Microscopy for microstructure characterization, X-ray absorption spectroscopy from NSRRC, to quantify different components by linear combination of standard compounds, and photo-electron spectroscopy in air coupled with UV-Visible absorption spectroscopy to find the relationship between band position and photocatalytic reactivity. We tried optimizing efficiency of the tin disulfide by: sampling different solvents (ethylene glycol, ethanol, and deionized water ) in the microwave reaction, testing different reaction times (5 min - 120 min), and altering the concentration of SDS (0-2000%). We found that by synthesizing tin disulfide in deionized water with 1% SDS for 1 hour we achieved a QE of 0.028%, which is 25 times better than the commercial tin disulfide. Furthermore, the CO2 reduction reaction resulted in the formation of acetaldehyde, implying eight electrons transferred. In total, we found a new process for the synthesis of tin disulfide that demonstrates a significant enhancement to the reduction activity of carbon dioxide.
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量子效率, 太陽光, 光催化, 二氧化碳, 二硫化錫, 乙醛, 十二烷基硫酸鈉 (SDS), Quantum Efficiency, Solar Energy, Carbon Dioxide, Tin Disulfide, Acetaldehyde, Sodium dodecyl sulfate (SDS), Photocatalyst