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以一步法原位合成了g-C_3N_4/ZnO异质结复合材料,评价其在可见光下降解亚甲基蓝(MB)的光催化活性,并探讨了g-C_3N_4/ZnO的光催化机制。运用XRD、FTIR、SEM和UV-Vis DRS对所合成的复合材料进行表征。结果表明,经复合后g-C_3N_4和ZnO紧密结合,构建了异质结,提高了光生电子空穴的分离效率,并且在可见光区表现出较强的光响应性;当g-C_3N_4的质量分数为19%时,复合材料g-C_3N_4/ZnO降解MB的反应速率常数为0.020 6 min-1,是纯g-C_3N_4的3.8倍。催化剂重复使用5次,仍保持较高的光催化活性。 相似文献
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以一步法原位合成了g-C3N4/ZnO异质结复合材料,评价其在可见光下降解亚甲基蓝(MB)的光催化活性,并探讨了g-C3N4/ZnO的光催化机制。运用XRD、FT-IR、SEM和UV-Vis DRS对所合成的复合材料进行表征。结果表明,经复合后g-C3N4和ZnO紧密结合,构建了异质结,提高了光生电子-空穴的分离效率,并且在可见光区表现出较强的光响应性;当g-C3N4的质量分数为19%时,复合材料降解MB的反应速率常数为0.0206min-1,是纯g-C3N4的3.8倍。催化剂重复使用5次,仍保持较高的催化活性。 相似文献
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以g-C_3N_4为基底,通过掺杂Fe元素,复合MoS_2的方法制备了具有多孔异质结结构的MoS_2/Fe-g-C_3N_4半导体材料,并测量了其光解水产氢性能,发现MoS_2含量为3%(以g-C_3N_4的质量为基准,下同)时,MoS_2/Fe-g-C_3N_4的光催化性能优异,其产氢速率达到48.2μmol/h,为g-C_3N_4的5.48倍。利用XRD、FTIR、SEM、TEM、XPS表征了催化剂的物化性质;利用PL、UV-Vis等方法表征了催化剂的光学性质。结果发现,Fe元素的掺杂使g-C_3N_4结晶度降低,并呈现一种交叉孔道结构,极大增加了催化剂的比表面积。同时,MoS_2可以与g-C_3N_4形成异质结结构,提高了MoS_2/Fe-g-C_3N_4的可见光吸收率以及光生电子-空穴对的分离效率,从而有效提高了MoS_2/Fe-g-C_3N_4光解水产氢的能力。 相似文献
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以三聚氰胺、二水合钼酸钠和五水合硝酸铋为原料,采用溶剂热法制备了g-C3N4/Bi2MoO6前驱体,然后通过共沉淀法将Ag3PO4纳米粒子负载在前驱体上,得到g-C3N4/Bi2MoO6/Ag3PO4复合材料。通过XRD、FTIR、XPS、SEM、UV-Vis DRS等对复合材料进行表征。结果表明,g-C3N4、Bi2MoO6和Ag3PO4之间形成了异质结结构,促进光生电子-空穴对的有效分离。以盐酸四环素(TC)为目标降解物,分析材料的光催化活性。在可见光照射下,30 mg g-C3N4/Bi2MoO6/Ag3PO4在50 min内对40 mL 10 mg/L的TC溶液的降解率达到93%。降解速率常数为0.033 min-1,分别是g-C3N4、Bi2MoO6和Ag3PO4降解速率常数的33倍、3.6倍和1.5倍;g-C3N4/Bi2MoO6/Ag3PO4对TC进行降解,循环利用4次后,对TC的降解率为71%,说明g-C3N4/Bi2MoO6/Ag3PO4具有较好的稳定性。自由基捕获实验结果表明,g-C3N4/Bi2MoO6/Ag3PO4光催化降解TC的主要活性物种为·OH和·O2-。最后提出了TC可能的降解机理和降解路径。 相似文献
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《合成材料老化与应用》2017,(6)
通过固相加热制备g-C_3N_4,超声调控获得片层状g-C_3N_4,光照Ag NO3与g-C_3N_4成功制备了Ag/gC_3N_4复合光催化材料。利用X射线衍射仪(XRD)以及扫描电子显微镜(SEM)分析产物的物相和形貌,采用紫外-可见吸收光谱表征样品的光学性能。以罗丹明B为模拟污染物,评价超声样品Ag/g-C_3N_4的可见光(λ≥420nm)催化性能。实验结果表明,与纯g-C_3N_4相比,超声的Ag/g-C_3N_4复合光催化材料在可见光下降解罗丹明B的光催化活性最好。分析表明Ag与g-C_3N_4的协同作用抑制光生电子-空穴的复合是可见光催化活性增强的主要原因。 相似文献
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以尿素、醋酸锌、柠檬酸为主要原料,采用浸渍-热聚合法分别制备了ZnO/g-C_3N_4和CDs/ZnO/g-C_3N_4复合材料,考察了2种催化剂在可见光下对罗丹明B的光降解效率。利用XRD、TEM、XPS、UV-Vis DRS、FTIR对催化剂进行了表征和评价。结果表明:石墨相氮化碳(g-C_3N_4)呈片状,ZnO呈棒状,碳点(CDs)平均直径约为10 nm,呈单分散排布,分散性较好;且CDs/ZnO/g-C_3N_4仍保持石墨相g-C_3N_4的晶型结构,三元组分相互协同作用使CDs/ZnO/g-C_3N_4在可见光下,光照时间为210 min,对质量浓度为8 mg/L的RhB溶液表现出优异的光催化性能,其降解罗丹明B的效果优于单体g-C_3N_4、ZnO及ZnO/g-C_3N_4,降解率可达到70%左右。 相似文献
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《现代化工》2018,(12)
采用光沉积法分别将Ag和MnOx有选择地负载到WO_3/g-C_3N_4复合光催化剂的g-C_3N_4和WO_3表面,制备出双助剂共同改性的Ag-MnOx/WO_3/g-C_3N_4复合光催化剂,通过XRD、TEM、FT-IR、DRS对样品进行表征,考察了Ag-MnOx/WO_3/g-C_3N_4在光催化降解罗丹明B(RhB)溶液的光催化活性。结果表明,Ag沉积在g-C_3N_4表面,MnOx沉积在WO_3表面,有效地促进了光生电子和空穴的分离,在光催化降解测试中,Ag-MnOx/WO_3/g-C_3N_4的降解速率是WO_3/g-C_3N_4的1. 87倍,且比负载单助剂的WO_3/g-C_3N_4NS和浸渍法制备的复合光催化剂降解速率更高。 相似文献
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A new ampholytic homopolypeptide, , which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO4 and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu2+ and Ca2+, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu2+ complex near 240 nm. Dependence of the peak intensity on pH at various q values () indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu2+ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu2+ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu2+-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation. 相似文献
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Silvia Schicker Daniel E. García Igor Gorlov Rolf Janssen Nils Claussen 《Journal of the American Ceramic Society》1999,82(10):2607-2612
Wet milling of Al2 O3 -aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al2 O3 and Fe2 O3 /Al/Al2 O3 powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe2 O3 /Al/Al2 O3 powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al2 O3 powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8. 相似文献
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Sintering kinetics of the system Si3 N4-Y2O3 -Al2 O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si3 N4 were studied with additions of 4 to 17 wt% Y2 O3 and 4 wt% A12 O3 . Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si3 N4 and glass or β '-Si3 N4 , α '-Si3 N4 , and glass. The compositions and amounts of the residual glassy phases are estimated. 相似文献
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Akira Akimoto 《Polymer》1974,15(4):216-218
The polymerization of vinyl chloride has been investigated using an catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed. 相似文献
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Mats Carlsson Mats Johnsson Mats Nygren 《Journal of the American Ceramic Society》1999,82(8):1969-1976
Ta0.33 Ti0.33 Nb0.33 C and Ta0.33 Ti0.33 Nb0.33 C x N1− x whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N2 . The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO2 , Ta2 O5 , Nb2 O5 , C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl2 ( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature. 相似文献