【作者】 陈秀芳；

【导师】 付贤智； 王心晨；

【作者基本信息】 福州大学 ， 材料化学， 2011， 博士

【摘要】 半导体光催化技术在温和条件下能将太阳能转化成化学能，同时能彻底氧化分解有机物，在解决环境污染和能源短缺方面表现出巨大的潜力。然而，传统TiO2基无机半导体光催化剂存在太阳能利用率低、光量子效率低和易失活的弊端，严重地制约了光催化技术的实际推广应用。因此，开发新型高效光催化剂和拓宽光催化剂的光响应范围，成为当前光催化领域的研究热点。石墨相氮化碳（g-C₃N₄）具有良好的化学惰性、热稳定性以及生物兼容性等，有可能在各种材料科学应用中替代石墨碳材料。g-C₃N₄是一种有机半导体材料，禁带宽度约2.7eV，具有合适的导带价带位置，在光催化领域有着诱人的应用前景。本论文在不破坏半导体光催化材料的基本化学结构的基础上，通过对g-C₃N₄基体的改性来提高其光催化性能，主要包括：（1）通过热聚合法合成体相g-C₃N₄，在空气和氮气中对其进行后退火处理，研究后退火对结构、光学性质和光催化性能的影响。研究发现，后退火可以有效提高g-C₃N₄光解水制氢的活性。（2）采用硬模板法合成有序介孔结构的g-C₃N₄，发现其光电性能和光催化分解水产氢性能都优于体相g-C₃N₄。（3）将金属离子引入g-C₃N₄结构，研究金属-氮化碳化合物在有机光催化合成中的应用。研究结果表明，金属改性不仅改进了氮化碳的电子结构和光学性能，且从基团和催化功能上模拟生物氧化酶，在温和的条件下实现对过氧化氢和分子氧的催化活化，在苯羟基化反应以及苯乙烯环氧化反应中都表现出较高的催化活性和选择性;（4）通过浸渍-化学表面反应技术，将金属-氮化碳化合物负载于氧化硅载体上，得到具有大比表面积的纳米材料，并考察负载样品对苯羟基化反应的活性。研究结果表明，Fe-g-C₃N₄负载样品具有优良的催化氧化能力，与体相材料相比，负载样品的催化性能提高了2.7倍。（5）采用硬模板法合成介孔g-C₃N₄，通过溶剂热法与无机半导体CdS进行复合改性，发现复合材料具有优良的光催化氧化有机污染物和还原水制氢性能。本论文的创新点：（1）首次对体相g-C₃N₄光催化剂进行后退火处理，通过优化制备工艺来提高其光催化效率；（2）以SBA-15为模板成功合成了有序介孔g-C₃N₄，研究其光电性能和光催化分解水产氢性能；（3）通过简单的软化学法在g-C₃N₄中成功引入金属离子，得到金属-氮化碳新型催化剂，并首次应用于有机光催化合成。（4）首次将金属-氮化碳化合物负载于SBA-15，得到具有高分散纳米结构的负载型金属-氮化碳化合物。研究发现，对苯羟基化反应，负载样品具有优于体相样品的反应活性。（5）采用溶剂热法制备了CdS/介孔g-C₃N₄复合材料，从优化体相织构和调控能带结构来提高g-C₃N₄光催化降解有机污染物和分解水产氢活性。更多还原

【Abstract】 Semiconductor photocatalytic technology could convert solar energy to chemical energyunder mild reaction condition, and degrade many organics completely, consequently, it has greatapplied potential in solar energy conversion and environmental pollution control. However,traditional TiO2-based inorganic semiconductor photocatalysts have some defects, such as poorsolar energy utilization, low quantum efficiency and easily deactivation. These seriously limit thelarge-scale application of photocatalytic technology. Therefore, to develop new photocatalystswith high efficiency and to broaden photoresponse range of the photocatalysts have becomechallenging topics in the environmental photocatalytic field.Graphitic carbon nitride （g-C₃N₄） has good chemical inertness, thermal stability andbio-compatibility, which are promising candidates to complement carbon in materialsapplications. The graphitic carbon nitride polymer is an organic semiconductor material,exhibiting a band gap of2.7eV, with an appropriate conduction band and valence band position,thus, it has great applied potential in photocatalytic field. In the present research, g-C₃N₄wasmodified by many ways to enhance its photocatalytic performance without destroying the basicchemical structures, including:（1） Bulk g-C₃N₄was firstly prepared by thermal polymerization,and then post-annealed in air and nitrogen atmosphere. The effect of annealing in the structure,optical properties and photocatalytic performance of g-C₃N₄was studies. The results show thatpost-annealing can effectively improve the photocatalytic activity for hydrogen evolution;（2）Ordered mesoporous structure of g-C₃N₄was prepared by using hard template. It was found thatits photoelectric property and photocatalytic efficiency for H2evolution was much better thanthat of the bulk sample;（3） Metal ions were introduced into g-C₃N₄structure and the applicationof metal containing carbon nitride in photocatalytic organic synthesis were studied. The resultsshow that the modification of g-C₃N₄by metal irons not only improves the electronic structureand optical properties of carbon nitride, but also achieves the activation of hydrogen peroxideand molecular oxygen under mild conditions by simulating bio-oxidation enzyme via the groupsand catalytic functional. The modified samples show high catalytic activity and selectivity inboth direct oxidation of benzene to phenol and styrene epoxidation;（4） Metal containing carbonnitride was loaded on the SBA-15by the impregnation-chemical modification method andnanostructured materials with large surface area were obtained. The photocatalytic/catalyticactivities were evaluated by oxidation of benzene to phenol. The results show that the well-dispersed Fe-modified nanomaterials exhibited excellent catalytic activity in the oxidationof benzene,2.7times higher than that of bulk materials;（5） Mesoporous g-C₃N₄was prepared byhard template method, and then coupled with inorganic semiconductor CdS by solvethermalprocess. It was found that the CdS/mpg-C₃N₄composites exhibited excellent photocatalyticactivity in both decomposition of organic pollution and water splitting for H2.The original results of this study are as follows:（1） Bulk g-C₃N₄was firstly treated bypostcalcination, and the photocatalytic activity of g-C₃N₄was enhanced from the optimization ofthe preparation procedure;（2） Ordered mesoporous g-C₃N₄was successfully prepared by hardtemplate method with SBA-15as template. The photoelectric property and photocatalyticactivity for H2evolution of the mesoporous g-C₃N₄were fully studied;（3） Metal ions weresuccessfully introduced into g-C₃N₄matrix by a simple soft-chemical method. The novel metalcontaining carbon nitride materials were firstly applied in photocatalytic organic systhesis;（4）Metal containing carbon nitride compounds were firstly loaded on the SBA-15, andwell-dispersed M-g-C₃N₄/SBA-15composites were obtained. It was found that theFe-g-C₃N₄/SBA-15nanomaterials exhibited higher catalytic activity for the oxidation of benzenethan bulk materials;（5） The mesoprous g-C₃N₄were coupled with CdS with solvothermaltreatment, the photocatalytic performance in decomposition of organic pollution and watersplitting for H2of g-C₃N₄were enhanced from optimization of texture structure and adjustmentof band structure.更多还原