- 學位論文
二硫化錫於可見光驅動光催化分解水產氫之研究
Applications of Tin Disulfide in Visible-light Driven Photocatalytic Water Splitting for Hydrogen Production
摘要
近年來在光催化分解水產氫的領域上有越來越多的研究團隊將研究重心放在可見光應答之材料上。目前可見光分解水產氫之領域以硫化鎘為主要被探討之光觸媒。雖然硫化鎘具備在可見光照射下之產氫能力，其穩定性及毒性使得該觸媒在使用上有其疑慮。而二硫化錫為一無毒性、便宜及化學穩定性高之n型半導體材料。其能隙為2.2 ~2.35 eV，為一可見光應答之材料。且文獻中提及之二硫化錫能帶結構符合光催化分解水之基本條件，為一可發展之材料。本研究希冀藉由對二硫化錫的結構及其在可見光分解水產氫的應用之了解，將此材料視為一未來有機會取代硫化鎘之可見光觸媒。 本研究中以五水合四氯化錫及硫代乙醯胺作為前驅物合成出大小為15至40奈米之奈米片，經XRD確認為二硫化錫。由TEM觀察其厚度約為十數層單層所組成之片狀結構。比表面積最高之樣品SnS2-160-12可達到105〖 m〗^2/g，為界孔洞材料。其能隙經過紫外-可見光吸收圖譜之檢測後判定為2.1 eV。本研究採用之光觸媒產氫之反應系統為內照式，並以400 W高壓汞燈照射，1M亞硝酸鈉作為濾光液，其中以硫化鈉與亞硫酸鈉作為犧牲試劑。經產氫測試結果二硫化錫之產氫速率為28 μmol/hr，為本研究合成之硫化鎘產氫速率之1.24倍。經過五個五小時之循環測試後，二硫化錫之產氫能力僅表現出些微之衰減。 本研究亦把硫化鎘奈米棒作為主體並以二硫化錫奈米粒子修飾於其上。由SEM及TEM皆可以看到有明顯的奈米粒子修飾於主體奈米棒上，並經由晶面間距及XPS分析確認該奈米粒子為二硫化錫。兩半導體材料複合後形成異質接面，其能帶結構匹配電子電洞將能夠有效地分離至兩材料，藉此減緩電子電洞對再結合，改善其產氫能力。而SnS2-20/CdS-160-12此一樣品之產氫速率可達43 μmol/hr，約為純硫化鎘產氫速率之1.9倍。
並列摘要
In the research area of photocatalytic water splitting for hydrogen production area, there are increasingly more and more research groups placputting their efforts on visible light driven materials. Cadmium sulfide is probably Up to now, the most thoroughly investigateddiscussed visible light driven photocatalystmaterial would be cadmium sulfide. Although cadmium sulfide does possess the ability to produce hydrogen under visible light irradiation, its instability and toxicity are majorstill our concerns. Tin disulfide is an n-type semiconductor which is non-toxic, inexpensive, and chemically stable. Tin disulfide is a visible light driven material since its band gap is onlyranges from 2.2~2.35 eV. According to literaturethe reference, its band structure is also suitable for hydrogen production, which makes ittin disulfide a promising alternative visible light driven photocatalyst to material that might replaces cadmium sulfide. We use tin(IV) chloride pentahydrate and thioacetamide as theour precursors to synthesizes tin disulfide nanoplates with a hydrothermal process. The productwith platearticle sizes rangesing from 15 to 40 nm. XRD data confirms that they are all products obtained are tin disulfide. TEM images shows that the lamellar structure is composed of more than ten layers in the thickness direction. Tin disulfide obtained at a reaction temperature of 160 oC and reaction time of 12 hours, SnS2-160-12, is shown to be SnS2-160-12, a meso--porous with amaterial, possesses the highlargest specific surface area of which reaches 105.4657〖 m〗^2/g. The band gap, is 2.1 eV, which is determined by UV-visible absorption spectrumspectra, is 2.1 eV. TheOur photocatalytic reactor is with an designed to be inner illumination light source,ed a by 400 W high-pressure mercury lamp. A solution of In order to filter UV light, 1M NaNO2 is usedchosen to be the filter out all lights with wavelengths shorter than 420 nmsolution. Na2S and Na2SO3 serve as theare the sacrificial agents in our system. According to our the results, tin disulfide could produces hydrogen atwith the rate of 287.718 μmol/hr, which is 1.24 times of thate rate of cadmium sulfide. In additionMoreover, we try to decorate cadmium sulfide nanorods are decorated with tin disulfide nanoparticles to form a heterojunction composite photocatalyst. It is evidentobvious to see from SEM and TEM images that tin disulfidethere are lots of nanoparticles are successfully decorated onto the surfaces of attached on the cadmium sulfide nanorods from the SEM and TEM. With the help of HR-TEM and XPS analyseis, we are certain that the nanoparticles are tin disulfide. These two semiconductor materials would formcreate a staggered heterojunction, enabling and their matching band structures makeimproved charge separation electron-hole pair well separated. Owing to this effect, electron-hole pair recombination isshould be retardedduced, which improvesmakes better the hydrogen production ability of the composite photocatalyst. Sample SnS2-20/CdS-160-12 could produces hydrogen atwith the rate of 432.609 μmol/hr, which is 1.9 times of thate rate of pure cadmium sulfide