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排序方式: 共有493条查询结果,搜索用时 31 毫秒
321.
Yong Dou Lu Yang Lan Qin Yunhui Dong Zhen Zhou Daopeng Zhang Suna Wang 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(6):616-624
The solar photocatalysis of water splitting represents a significant branch of enzymatic simulation by efficient chemical conversion and the generation of hydrogen as green energy provides a feasible way for the replacement of fossil fuels to solve energy and environmental issues. We report herein the self‐assembly of a CoII‐based metal–organic framework (MOF) constructed from 4,4′,4′′,4′′′‐(ethene‐1,1,2,2‐tetrayl)tetrabenzoic acid [or tetrakis(4‐carboxyphenyl)ethylene, H4TCPE] and 4,4′‐bipyridyl (bpy) as four‐point‐ and two‐point‐connected nodes, respectively. This material, namely, poly[(μ‐4,4′‐bipyridyl)[μ8‐4,4′,4′′,4′′′‐(ethene‐1,1,2,2‐tetrayl)tetrabenzoato]cobalt(II)], [Co(C30H16O8)(C10H8N2)]n, crystallized as dark‐red block‐shaped crystals with high crystallinity and was fully characterized by single‐crystal X‐ray diffraction, PXRD, IR, solid‐state UV–Vis and cyclic voltammetry (CV) measurements. The redox‐active CoII atoms in the structure could be used as the catalytic sites for hydrogen production via water splitting. The application of this new MOF as a heterogeneous catalyst for light‐driven H2 production has been explored in a three‐component system with fluorescein as photosensitizer and trimethylamine as the sacrificial electron donor, and the initial volume of H2 production is about 360 µmol after 12 h irradiation. 相似文献
322.
Elnaz Ranjbakhsh Mohammad Izadyar Ali Nakhaeipour Aziz Habibi-Yangjeh 《International journal of quantum chemistry》2020,120(23):e26388
The photocatalytic yield of g-C3N4 for CO2 reduction was modified by phosphorus doping. Possible reaction pathways for CO2 reduction on the P-doped g-C3N4 (PCN) surface were investigated by density function theory calculations for the first time. The experimental results showed that P doping increases the carriers' lifetime, which improves the production of CH4 through the increase in the driving force of the electrons. The partial density of states of the PCN showed that the valence band maximum and conduction band minimum are composed of px, py, and, s orbitals of the N atoms and pz states of carbon, nitrogen, and phosphorus, respectively. Mechanism studies confirm that formic acid, formaldehyde, methanol, and methane are the most probable products. Methane, having positive adsorption energy, can be easily desorbed from the PCN surface, and the Gibbs activation energy of the final step is 1.98 eV. The formation of H2COOH is the rate-determining step. 相似文献
323.
以Cu(NO3)2·3H2O和P25为前躯体,通过简单浸渍法制备了CuO/TiO2光催化剂,利用N2物理吸附、XRD、TEM、UV-vis漫反射光谱分析了催化剂的结构特性。研究了Cu组分的负载量、催化剂在反应液中的分散量、催化剂焙烧温度、反应液中甲醇浓度对CuO/TiO2光催化反应产氢活性的影响,并考察了催化剂的稳定性,提出了该体系光催化反应的机理。结果表明,Cu的适宜负载量为2.0%~7.5%(质量分数),在Cu质量分数2.0%、催化剂焙烧温度350℃、甲醇的体积浓度为10%、催化剂分散量为1.0 g/L时,产氢活性可达到1 022 μmol/(h·g),并且该催化剂具有较好的稳定性。 相似文献
324.
Yushuai Jia Jingxiu Yang Dan Zhao Hongxian Han Can Li 《天然气化学杂志》2014,(4):420-426
A novel Sr2CuInO3 S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3 S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations(DFT) and electrochemical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3 S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocatalytic hydrogen production experiments under a visible light irradiation(λ420 nm) were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3 S and Rh was found to be the best one among the tested ones. 相似文献
325.
WU Ren-Ping GUO Jin-Yu Chen Zhu-Ling YU Yan② 《结构化学》2008,27(10):1245-1249
Recoverable TiO2 photocatalysis material supported by silicon powder was prepared with sol-gel method, afterwards the silica gol and sodium silicate were used as molding binder respectively to investigate their effects (including binder type and binder addition quantity) on the crystal structure and catalysis properties of photocatalyst. In this work, the catalysis activity was defined as the degradation rate of methyl orange solution upon ultraviolet lamp irradiation, and the specific areas were determined with nitrogen desorption method. TiO2 crystal form was measured with X-ray powder diffraction and their micro-morphology was observed with SEM. Experimental results indicate that these two binders do not affect the crystal form transformation of TiO2, but silica gol can increase the specific surface area of TiO2 photocatalyst obviously and the addition of sodium silicate can decrease it. In all, silica gol is a better candidate than sodium silicate for higher catalysis property. In conclusion, 6% silica gol is the optimal addition concentration. Under this condition, the ratio of anatase to rutile TiO2 is 64:36, the specific area is 29.67 m^2/g, and as expected, the degradation rate of methyl orange could be as high as 90% after irradiation for 5 days. 相似文献
326.
空气电极/AC作载体对TiO2光催化性能的影响 总被引:2,自引:0,他引:2
研究了空气电极和活性碳 (AC)作载体对TiO2 光催化氧化活性艳红 (K 2BP)性能的影响 .实验结果表明 ,用空气电极 /AC作载体能显著提高TiO2 的光催化反应速度 ;空气电极不仅具有良好的合成H2 O2 的性能 ,而且对TiO2 光催化剂可产生大约 +0 .5V的偏压作用 ,大大减小了TiO2 光生电荷的复合几率 ;AC对有机物分子良好的吸附作用提高了有机物分子在TiO2 表面及周围的富集浓度 ,其含量在 2 1%左右可使光催化剂达到最佳的催化效果 .复合电极工作电流密度对活性艳红的氧化脱色速度有影响 ,i=15mA/cm2 ,速度达到最大 ;活性艳红分子在复合电极表面的吸附受溶液pH值的影响 ;提出了复合电极的工作原理 . 相似文献
327.
玻璃微珠/Ag/TiO2可见光催化剂的制备与表征 总被引:1,自引:0,他引:1
通过离子交换法将Ag纳米颗粒负载于玻璃微珠的表面及浅表层,并以钛酸四丁酯的乙醇溶液为前驱体,将TiO2负载于包含银的玻璃微珠表面,制得一种玻璃微珠/Ag/TiO2复合光催化剂。由于纳米银的表面等离子体吸收效应,该复合光催化剂具有一定的可见光响应特性。利用XRD、SEM对样品进行表征,可发现玻璃微珠表面形成一层均匀多孔的锐钛矿TiO2,其粒径均在50 nm左右。由漫反射光谱可得出该催化剂具有较强的可见光吸收,并在降解甲基橙溶液的试验中表现出较好的可见光催化活性。 相似文献
328.
The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory. Highly efficient visible-light-induced nitrogen or/and praseodymium doped anatase TiO2 nanocrystal photocatalyst were synthesized by a microwave chemical method. The calculated results show that the photocatalytic activity of TiO2 can be enhanced by N doping or Pr doping, and can be further enhanced by N+Pr codoping. The band gap change of the codoping TiO2 is more obvious than that of the single ion doping, which results in the red shift of the optical absorption edges. The results are of great significance for the understanding and further development of visible-light response high activity modified TiO2 photocatalyst. The photocatalytic activity of the samples for methyl blue degradation was investigated under the irradiation of fluorescent light. The experimental results show that the codoping TiO2 photocatalytic activity is obviously higher than that of the single ion doping. The experimental results accord with the calculated results. 相似文献
329.
核-壳式纳米SnO2/TiO2光催化剂的制备和性能 总被引:8,自引:0,他引:8
以纳米SnO2·nH2O胶体粒子为基质,采用活性层包覆法制备了纳米SnO2/TiO2复合光催化剂,并用R,TEM,XPS和XRD等手段进行了表征. 采用敌敌畏的光催化降解反应对所制催化剂的活性进行了评价. 结果表明,SnO2/TiO2为核-壳结构,粒径约为12 nm. SnO2/TiO2的光催化活性受TiO2含量及SnO2·nH2O乙醇溶液含水量的影响. 最佳条件为SnO2/TiO2中TiO2含量为56.45%,SnO2·nH2O乙醇溶液含水量为20%. 所制SnO2/TiO2光催化活性比纯TiO2显著提高,且光催化活性稳定,可重复使用. 相似文献
330.
Hydrogen produced from water splitting is a renewable and clean energy source. Great efforts have been paid in searching for inexpensive and highly efficient photocatalysts. Here, significant enhancement of hydrogen production has been achieved by introducing ≈1 mol% of MoS2 to Cu2ZnSnS4 nanoparticles. The MoS2/Cu2ZnSnS4 nanoparticles showed a hydrogen evolution rate of ≈0.47 mmol g−1 h−1 in the presence of sacrificial agents, which is 7.8 times that of Cu2ZnSnS4 nanoparticles (0.06 mmol g−1 h−1). In addition, the MoS2/Cu2ZnSnS4 nanoparticles exhibited high stability, and only ≈3% of catalytic activity was lost after a long time irradiation (72 h). Microstructure investigation on the MoS2/Cu2ZnSnS4 nanoparticles reveals that the intimate contact between the nanostructured MoS2 and Cu2ZnSnS4 nanoparticles provides an effective one‐way expressway for photogenerated electrons transferring from the conduction band of Cu2ZnSnS4 to MoS2, thus boosting the lifetime of charge carriers, as well as reducing the recombination rate of electrons and holes. 相似文献