Synthesis and characterisation of nano-sized nickel titanate photocatalyst

Visible light activated nickel titanate (NiTiO₃) nanopowders were synthesised by a simple and organic-free co-precipitation method. X-ray diffraction and transmission electron microscopy were used to characterise the crystal structure. The average crystalline size of the synthesised nickel titanate is found to be 100?nm. The visible light photocatalytic activity was evaluated on the basis of photobleaching of methyl orange in aqueous solution. The results show that NiTiO₃ exhibits good photocatalytic activity under visible light irradiation. The enhanced photocatalytic activity of nickel titanate under visible light is due to the lower band-gap value of nickel titanate (3.10?eV) compared to that of TiO₂ (3.23?eV).     

硫掺杂TiO2的制备及其光催化降解次甲基蓝研究

以TiCl4、(NH4)2SO4为原料,采用溶胶-凝胶法制备了硫掺杂纳米TiO2,利用XRD、TEM、FTIR等对样品进行了表征,并将其用于光催化降解次甲基蓝溶液.结果表明:制备的纳米TiO2为锐钛矿晶型,具有超强酸特征,平均粒径分布为10～30nm,S掺杂对TiO2的晶粒长大有抑制作用,经过硫掺杂的纳米TiO2光催化活性明显优于纯TiO2.     

A型沸石膜的制备及其在气体脱湿中的应用

用水热合成法合成了Ａ型沸石膜，探讨了Ａ型沸石膜的制备方法和工艺条件；用ＸＲＤ，ＳＥＭ等对沸石膜进行了表征；考察了沸石膜对Ｎ２、Ｈ２的分离性能；对沸石膜脱湿性能进行了研究。     

Synthesis and photocatalytic activity of mesoporous cerium doped TiO2 as visible light sensitive photocatalyst

Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N₂ adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 °C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 °C shows better activity than that calcined at 400 °C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce⁴⁺/Ce³⁺ rather than only visible light absorption.     

Synthesis of sea urchin-like cuprous oxide with hollow glass microspheres as cores and its preliminary application as a photocatalyst

Cuprous oxide (Cu₂O) microcrystals with sea urchin-like morphologies were successfully prepared on the surface of hollow glass microspheres (HGMs) using sodium sulfite (Na₂SO₃) as the reducing agent and sodium acetate–acetic acid (NaAc–HAc) as buffer solution in copper sulfate (CuSO₄) solution. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential thermal-thermogravimetry (DTA-TG), and visible spectrophotometer. Based on the SEM images of the as-obtained samples, it was found that the HGMs played a crucial role in the formation of sea urchin-like Cu₂O. Meanwhile, the stirring time was also important for coating process. The as-prepared sea urchin-like microcrystals are cubic phase Cu₂O. The as-prepared products can be oxidized at 240 °C. The preliminary study on the photocatalytic behavior of the sea urchin-like Cu₂O showed that the photodegradation efficiency of 40 mg/L methyl orange (MO) reached 95.15% within 30 min.     

A visible light response TiO2 photocatalyst realized by cationic S-doping and its application for phenol degradation

S-doped TiO2 photocatalyst with high visible light activity was prepared by acid catalyzed hydrolysis method using thiourea (TU) as sulfur source. The catalyst was characterized by DRS, XPS, XRD, FTIR, SEM and N2 adsorption. It was found that cation S6+ was homogeneously incorporated into the bulk phase of TiO2 and substitutes for some of the lattice titanium (Ti4+). Doped S can form a new band above the valence band and narrow the band-gap of the photocatalyst, giving rise to a second absorption edge in the visible light region. The activity of the catalyst was examined by photodegradation of phenol in aqueous solution under both artificial visible light and solar light irradiation. The activity of catalyst was found to be dependent on the doping amount of S and the maximum activity was observed when the catalyst was obtained by calcinated at 600 degrees C with the mass ratio of TU/TiO2=1. Too much of new-generated band-gap structures due to higher S-doping could act as recombination centers for electron-hole pairs. Catalyst with optimum S-doping exhibited the highest activity under both artificial light and solar irradiation for phenol degradation. In addition, doped S also beneficial for the better dispersion, large S(BET) and phase transformation retardation of TiO2.     

钢渣制备水滑石阻燃剂及其在EVA复合发泡材料中的应用

以钢渣为原料合成了磷酸根型水滑石(P-LDHs),并用十二烷基硫酸钠(SDS)插层P-LDHs得到改性水滑石(SDS-P-LDHs).分别将P-LDHs,SDS-P-LDHs和膨胀石墨、EVA共混,发泡得到EVA复合发泡材料.利用XRD,XRF,FT-IR,SEM,TEM对P-LDHs和SDS-P-LDHs的形貌结构进行表征.结合极限氧指数(LOI),垂直燃烧(UL-94),SEM,TG,拉伸强度、断裂伸长率等测试,讨论了P-LDHs和SDS-P-LDHs用量对EVA复合发泡材料的阻燃性能和力学性能的影响.结果表明,P-LDHs和SDS-P-LDHs的加入显著提高了EVA复合发泡材料的阻燃性能,可起到良好的成炭作用.相比P-LDHs,SDS-P-LDHs与EVA基体相容性更好,当SDS-P-LDHs添加量为30％(质量分数)时,LOI达到27.5％,UL-94达到V-0级别,拉伸强度和断裂伸长率分别为2.27 MPa和251％,体系综合性能达到最佳.     

Synthesis of nano-sized NaY zeolite composite from metakaolin by ionothermal method with microwave assisted

Nano-sized NaY zeolite had been synthesized from metakaolin by ionothermal method with microwave assisted. Its structure had been characterized by XRD, SEM, HREM, and its physicochemical properties and catalytic characteristics were studied. The results showed that the size of the product was 150–250 nm, relative crystallinity 69.16%, Si/Al ratio 5.02. Compared with conventional NaY zeolite, nano-sized zeolite composite had larger surface area and mesopore volume, better thermal stability, higher cracking activity, higher gasoline selectivity, lower coke and gas selectivity. So it has good industry application prospects.     

Recycling of steel slag as an alkali activator for blast furnace slag: geopolymer preparation and its application in composite cement

Clean Technologies and Environmental Policy - The recycling–utilization rate of steel slag in China is less than 30%. Steel slag is rich in CaO and can produce the Ca(OH)2 after hydration,...     

锌卟啉敏化TiO2光催化剂的原位法制备及其光催化性能研究

以锌卟啉为敏化剂,采用溶剂热法原位合成了锌卟啉敏化TiO2复合光催化剂。利用XRD、SEM、UV-Vis DRS和TG-DTA对所得锌卟啉-TiO2复合光催化剂进行了表征和分析。分析结果表明,采用原位合成法能使锌卟啉原位负载于TiO2表面,且未改变TiO2的晶型和形貌;锌卟啉的存在使TiO2在可见光区域出现吸收峰,采用原位合成法制备的金属卟啉敏化TiO2光催化剂相对于溶剂回流法制备金属卟啉敏化TiO2光催化剂有更好的热稳定性和更好的催化降解亚甲基蓝性能。     

Preparation and properties of ce-doped TiO2 photocatalyst

TiO₂ nanoparticles doped with different content of Ce ion were prepared by sol–gel method. The samples were characterized by XRD, XPS, TEM, UV–Vis, and PL, the photocatalytic activity was evaluated by photocatalytic degradation of methylene blue (MB) under the irradiation of fluorescent lamp. The results indicate that Ce ion is incorporated into the lattice of TiO₂, which can restrain the increase of grain size, broaden the absorption region to visible light, and inhibit the recombination of the photo-generated electron and hole pairs. Moreover, the photocatalytic activity of Ce-TiO₂ in MB degradation is evidently enhanced. The MB degradation rate of the sample with Ce:Ti = 0.33% (molar ratio) in 8 h is 90.03%, which is much higher than that of P25 (68.19%).     

Sulphur,nitrogen-doped TiO2/graphene oxide composites as a high performance photocatalyst

Sulphur (S), nitrogen (N)-doped TiO₂/graphene oxide (GO) composites were environmentally friendly synthesised using thiourea (CS(NH₂)₂) as a binary-element doping reagent by a simple colloidal blending method. The S, N-doped TiO₂/GO composites show higher photocatalytic degradation rates on methyl orange (MO) compared to TiO₂. The average value of k (the apparent rate constant) for the S, N-doped TiO₂/5%GO (k?=?0.035?min^?1) was found to be eight times higher than that of TiO₂ grown in solution (k?=?0.0038?min^?1) and four times higher than that of P25 (k?=?0.008?min^?1). The investigation showed that the contribution of GO to the high photocatalytic activities of the composites come from its high specific surface area, oxygen-containing functional groups and large aromatic domains that were inclined to be bound by conjugated MO molecules via π–π stacking. The doping of S and N can increase the numbers of photo-generated electrons and holes, which produce more charge carriers to form reactive species, and thus promote the degradation of MO. This work could offer a route to improve the photocatalytic activities of TiO₂ and facilitate their application in reality.     

碳掺杂TiO_2光催化剂的制备与性能研究

以葡萄糖和钛酸四丁酯为原料,采用溶胶-凝胶法制备了C-TiO2光催化剂粉体。利用XRD、XPS、Raman、PL、UV-Vis等对样品进行表征分析,研究了不同制备条件对样品性能的影响,并以亚甲基蓝(MB)作为目标降解物,研究了其光催化性能。结果表明,碳掺入到TiO2晶格中,促进了样品由锐钛矿相向金红石相的转变,拓展了TiO2在可见光区的光谱响应范围,降低了光生电子和空穴的复合几率。当n(C)∶n(Ti)=0.30,400℃条件下焙烧4h制备的样品催化性能最好,在普通日光灯下3h内对MB的降解率达90.17%,显著高于同等实验条件下的Degussa P25(49.71%)。     

氮掺杂TiO2光催化剂研究进展

对TiO2光催化剂进行改性,实现可见光催化活性是第二代光催化剂走向实用化的关键.氮掺杂TiO2是一种理想的具有可见光活性的光催化剂,由于N 2p态与O 2p态杂化,实现带隙窄化和吸收带边红移,对于实现可见光催化活性具有重要意义.评述了氮掺杂改性TiO2光催化剂的国内外研究现状,分析了不同掺杂方法对于实现TiO2可见光催化活性的掺杂机理和改性机理,提出研究合适的催化剂载体对TiO2进行氮等非金属负载是今后努力的方向,并且应该建立统一的催化剂性能评价标准.     

Preparation and characterization of N-S-codoped TiO(2) photocatalyst and its photocatalytic activity

N-S-codoped anatase nanosized TiO(2) photocatalyst (NSTO) was successfully prepared by one-step hydrothermal method from a mixed aqueous solution of Ti(SO(4))(2) and thiourea. The samples were characterized by XRD, UV-vis, XPS, FT-IR and EA. From results of UV-vis, a red shift of the absorption edge was brought out owing to N and S codoping, and the extension for photoabsorption range of NSTO occurred. XRD, XPS, EA and FT-IR studies revealed that N and S were in situ codoped in the lattice of TiO(2) and N concentration decreased from the surface to the center of NSTO. Especially, the photocatalytic tests indicated that NSTO exhibited a high activity for decompositions of methyl orange both under UV-light and vis-light irradiation comparing to S-doped TiO(2) (STO) and undoped TiO(2) (TO). The high activity of NSTO can be related to the results of the synergetic effects of strong absorption in the UV-vis region, red shift in adsorption edge, oxygen vacancies and the enhancement of surface acidity induced by N and S codoping.     

Synthesis and characterization of AgO nanostructures by precipitation method and its photocatalyst application

In this research, a precipitation method was used in order to synthesize AgO nanostructures with the aid of silver nitrate as the starting reagent in an aqueous solution. To examine the effect of different surfactants such as glucose, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, and cetyltrimethylammonium bromide on the morphology and particle size of final products several tests were performed. The structural, morphological, and optical properties of as-obtained products were characterized by techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and ultraviolet–visible spectroscopy. Furthermore, the hysteresis loop measured at room temperature shows a ferromagnetic behavior of the AgO nanostructures. To evaluate the catalytic properties of nanocrystalline silver oxide (AgO), the photocatalytic degradation of rhodamine-B under visible light irradiation was carried out.     

Nanostructured TiO 2 photocatalyst and pump-probe spectroscopic study

Titanium dioxide (TiO₂), with its large band gap, has attracted much attention due to its excellent photocatalytic activity. TiO₂ ball-shaped nano-particles were deposited on silicon substrates by a thermal oxidation approach. With an increase in the annealing temperature the surface morphology and the structure of TiO₂ remained stable, exhibiting good heat stability; meanwhile, the hydrogen production rate also increased. The femtosecond pump-probe spectroscopic study showed that the lifetime of carriers of the samples as- deposited and post-annealed at different temperatures were longer than 20 ps.