【作者】 王力春；

【导师】 黎学明；

【作者基本信息】 重庆大学 ， 物理化学， 2007， 硕士

【摘要】 二氧化硫（SO₂）的大量排放造成了严重的大气污染,对人类的生存环境带来巨大的威胁,严格控制SO₂排放迫在眉睫,而采用有效手段动态连续监测大气中SO₂含量则是控制SO₂排放的前提。目前用于SO₂含量检测的方法仍存在一定不足,迫切需要研发可实时在线连续监测SO₂的新技术。多孔硅是一种以硅原子簇为骨架的海绵状新型功能材料,具有室温发光的特性且在SO₂气氛中其发光会发生猝灭,因此可以作为全固态新型传感基底材料。基于实验室前期工作,论文以n型单晶硅片作为原料,采用电化学阳极氧化法在单晶硅表面制备多孔硅薄膜并对其进行钝化处理,形成具有一定抗氧化能力同时具备SO₂传感性能的多孔硅材料。具体内容包括:（1）综述目前用于SO₂含量检测的国内外检测手段,分析多孔硅功能材料制备、钝化处理、应用的国内外研究现状及发展方向;（2）实验部分研究了电化学阳极氧化法制备多孔硅的条件,提出了形成多孔硅且用于SO₂气体传感的最佳制备条件:电流密度50mA·cm-2,电解液组成HF/C2H5OH=1:1（V/V）,阳极氧化时间为15min,同时采用300W碘钨灯照射其抛光面;提出了基于无机强酸和醇混合溶液的紫外光（UV）氧化法,考察了钝化处理后多孔硅发光的稳定性,结果表明经该方法钝化处理的多孔硅在空气中放置12个月后仍然保持良好的发光性能,钝化效果好且对SO₂气体非常敏感;（3）开展基于钝化多孔硅传感SO₂的定性、定量研究,获取了SO₂气体传感的响应时间和可逆性。结果表明钝化处理后的多孔硅对SO₂气体表现出良好的荧光猝灭特性和可逆性,多孔硅荧光猝灭幅度与SO₂浓度之间呈正相关;同时针对典型大气污染源其他气体的含量考察了多孔硅对SO₂的选择性,发现除NO2（>100ppm）会对多孔硅的发光产生轻微的影响外,其他气体（CO、CO2、NO）均无影响;最后结合分子猝灭的动力学原理和Stern-Volmer方程得到了多孔硅用于SO₂检测的分段线性响应范围为10¹4000ppm。更多还原

【Abstract】 SO₂ is a primary pollutant, which is the major factor leads to acid rain. Acid rain brings tremendous hazard to nature and human being. So monitoring SO₂ in environment is a critical part in pollution prevention. At present, several methods and instruments are available to monitor the concentration of SO₂ via different systems. However, these techniques have their own limits, such as high working temperature or the preparation of electrodes is complex, most of them involve big-sized analysis apparatus or complex test system, it can not monitor SO₂ in-situ. New approaches to the detection and analysis of SO₂ appear to be in urgent need.As novel functional material, porous silicon （PS） electrochemically etched in hydrofluoric acid （HF） solutions has attracted considerable interest because of its strong photoluminescence property under room temperature. The photoluminescence of the etched PS quenched in the SO₂ atmosphere and high concentration of typical atmospheric and industrial waste gases does not evoke a quenching response. Then lots of idea is presented to use PS as the material to detect the concentration of SO₂ in the air.Based on the former work of our team, n-type silicon wafer is used as the start material to prepare porous silicon film by electrochemical anodic oxidation, then a steady photoluminescence PS is obtained by surface passivation. It is expected to get a functional PS material which is anti-oxidized in the air and excellent sensing property to SO₂. The main points of this dissertation are as following:（1） It is summarized that the current studies situation and perspective orient of detecting SO₂, preparation mechanism and applied research status of porous silicon.（2） The optimal condition to prepare the PS for SO₂ detecting is presented: current density 50mA·cm-2, electrolyte HF/C2H5OH=1:1（V/V）, oxidized time 15min. Based on the former passivation methods, a new method is presented by immerging the fresh etched PS with inorganic acid and alcohol solution via UV-irradiation for 30min to obtain a stable photoluminescence PS. This method doesn’t diminish the sensitivity of PS to SO₂. It showed improved sensitivity and reversibility in response to SO₂. The photoluminescence of the passivated PS is very steady after it was stored in ait for 12monthes.（3）According to the experimental results of porous silicon sensing SO₂ qualitatively and quantitatively, it is discovered that photoluminescence quenching values of porous silicon oxidized by n-type single-crystal silicon wafers correlated with concentration of SO₂ positively. Moreover, researching the selectivity of passivated PS to SO₂ based on the typical pollution source, it shows that the selectivity of the PS is excellent, but the NO2 affects the selectivity only when its concentration is over 100ppm. According to dynamics mechanism of molecule quenching and Stern-Volmer equation, the linear response range of PS to detect SO₂ 10¹4000ppm is obtained.This technic applies the novel passivated PS and a mini-size fiber spectrometer to achieve SO₂ sensing process. This system is different from the big-sized analysis apparatus or complex test system. It is a simple, feasible and portable method to monitor SO₂.更多还原