非金属离子掺杂对二氧化钛光催化降解有机染料的研究进展

二氧化钛(TiO_2)是一种具有高化学稳定性、环境友好型和低毒性的半导体材料,广泛地应用于催化、传感、制氢、光学和光电等领域。然而作为光催化剂的二氧化钛存在带隙较宽、对太阳光的利用效率低等缺陷。通过对TiO_2改性,能增加晶体表面的活性位点或抑制光生载流子的复合,可以达到提高其光催化效率的目的。研究表明,将非金属离子掺杂到TiO_2的晶格中,可以减慢电子-空穴对的复合速率,是一种提高纳米TiO_2光催化活性的有效改性途径。讨论了非金属离子掺杂TiO_2的改性机理和使用非金属离子改性后的Ti O_2光催化剂降解常见有机污染物的最新进展,并对TiO_2光催化剂的改性前景做出展望。     

金属/磷酸银复合光催化剂的研究进展

磷酸银被发现是一种具有极高活性的可见光催化剂而受到密切关注。但单独的磷酸银半导体具有稳定性差等缺点,限制了其进一步应用。梳理发现构建金属/磷酸银复合光催化剂可以实现磷酸银光生载流子的有效分离,同时还可发挥纳米金属粒子的等离子体共振效应,从而提高复合光催化剂的催化活性和稳定性,此外还可借助其他助剂构建三元复合金属/磷酸银光催化剂。本综述对磷酸银光催化剂的改性研究具有指导意义。     

改性TiO_2光催化剂催化降解双酚A的研究进展

内分泌干扰物双酚A的污染日益严重,对人体健康和水生生物产生很大负面影响。光催化氧化法是废水净化常用的一种高级氧化技术。TiO_2是研究最多、最具潜力的光催化剂之一,但其带隙较宽、电子-空穴复合率较大而无法大规模应用,因此对TiO_2光催化剂进行改性得到广泛关注。介绍了近年来改性TiO_2光催化剂降解双酚A的研究进展,并提出改性TiO_2光催化剂今后的研究方向。     

TiO_2光催化剂掺杂改性的研究新进展

TiO2作为一种重要的光催化剂,对其进行掺杂改性可以有效的提高光催化活性。本文通过介绍金属与非金属的单掺、共掺对其光催化活性的影响,综述了近年来TiO2光催化剂在掺杂改性方面的研究进展。提出TiO2光催化剂在改性过程中亟待解决的问题及其在实际应用中的发展。     

TiO2光催化剂掺杂改性的研究新进展

TiO2作为一种重要的光催化剂,对其进行掺杂改性可以有效的提高光催化活性.本文通过介绍金属与非金属的单掺、共掺对其光催化活性的影响,综述了近年来TiO2光催化剂在掺杂改性方面的研究进展.提出TiO2光催化剂在改性过程中亟待解决的问题及其在实际应用中的发展.     

纳米TiO2的改性技术及其应用前景

针对半导体纳米TiO2粒子带隙较宽、光利用率低的缺点,对表面光敏化、掺杂过渡金属离子、表面沉积贵金属、复合半导体等几种提高TiO2光催化活性的改性方法进行了综述,介绍了各方法的机理以及研究现状,并对TiO2光催化剂的应用前景进行了展望。     

Fe~(3+)/g-C_3N_4光催化水制氢研究

g-C_3N_4是较为理想的非金属光催化剂之一,但其存在光生电子-空穴复合严重、光催化效率低下等缺点,严重影响了g-C_3N_4在光催化和能源领域内的应用,对其改性,提高光催化效率,就变得尤为迫切。通过高温法将混有Fe~(3+)的g-C_3N_4再次热处理制备Fe~(3+)/g-C_3N_4,并采用X射线衍射分析、X射线光电子能谱、紫外-可见漫反射光谱等对其进行了表征,并以Fe~(3+)/g-C_3N_4为催化剂光解水制氢。结果发现,该法成功制取了Fe~(3+)/g-C_3N_4,其产氢效率较g-C_3N_4提高2倍,达到158.1μmol/(g·h),说明Fe~(3+)掺杂g-C_3N_4能有效地提高氮化碳光催化制氢能力,具有潜在的应用价值。     

酯化改性甜菜粕铁配合物的制备及其催化性能

为使用低成本甜菜粕作高效催化剂降解染料废水,使用柠檬酸对脱果胶甜菜粕(DSBP)进行改性以引入羧酸基,然后将酯化改性甜菜粕(CDSBP)与Fe~(3+)进行配位反应,制备了柠檬酸改性甜菜粕纤维铁配合物(CDSBP-Fe)。通过FTIR、XRD和SEM对配合物表面形貌和化学结构进行了表征。将CDSBP-Fe作为非均相Fenton反应光催化剂,用于活性红195染料的降解反应,考察了其催化性能。结果表明:通过酯化反应羧酸基被成功引入纤维表面结构,并与Fe~(3+)进行配位反应制备了羧酸纤维铁配合物。在光辐射条件下,CDSBP-Fe能够促进偶氮染料的降解反应,反应25 min时,染料脱色率已达到95%;在pH=3～9时CDSBP-Fe均具有较好活性,且CDSBP-Fe循环5次使用活性也未明显降低。     

g-C3N4同型异质结复合光催化剂的制备及性能研究

石墨相氮化碳(g-C_3N_4)由于其合适的带隙和较高的物理化学稳定性等,被认为是一种有应用前景的光催化材料。然而,纯相g-C_3N_4的光催化性能和应用受到光生电子空穴易复合和比表面积相对较低等原因的限制。本文使用两种合适的前驱体(三聚硫氰酸与硫脲)共聚合有望优化高温煅烧过程中的缩聚过程,抑制团聚的发生,提高比表面积,同时形成的同型异质结能有效抑制光生载流子的再复合。在可见光照射下,形成的g-C_3N_4同型异质结复合光催化剂的活性明显高于单一的g-C_3N_4样品。显著增强的光催化活性主要归因于比表面积增大、活性位点增多和光生载流子再复合的有效抑制。     

改性二氧化钛光催化降解正丙硫醇的条件优化

采用溶胶-凝胶法制备了3种改性二氧化钛光催化剂,考察了停留时间、正丙硫醇初始浓度、相对湿度等因素对改性二氧化钛光催化降解正丙硫醇的影响,比较了3种改性二氧化钛光催化降解正丙硫醇的效果。结果表明,3种改性二氧化钛光催化降解正丙硫醇的效果依次为:Fe~(3+)改性Zn~(2+)改性ZnO改性;在停留时间为5.0～6.0s、相对湿度为50%时,Fe~(3+)改性二氧化钛对正丙硫醇的降解率达到70%以上,且正丙硫醇初始浓度越低,降解效果越好。     

生物炭基光催化剂的制备、性能及环境应用研究进展

生物炭因具有独特的表面性质、易修饰的官能团、良好的导电性和化学稳定性常被用作光催化剂的载体。将光催化剂与生物炭复合制备得到生物炭基光催化剂,不仅将二者的优势有效结合起来,同时得到的复合材料在官能团、孔性能、表面活性位点、催化降解能力等方面均有显著改善。生物炭良好的导电性提高了光催化过程中电子-空穴对分离的效率,丰富的表面官能团能够吸附固定不同的污染物,便于其光催化去除。本文综述了生物炭基光催化剂的各种制备工艺、催化性能及其对废水处理的影响,详细地介绍了溶胶-凝胶、超声、水热/溶剂热、水解、焙烧、沉淀和热缩聚等生物炭基光催化剂的制备方法。此外,还通过深入的机理分析,探讨了生物炭基光催化剂对污染物的吸附和光催化降解的协同效应。最后,归纳了生物炭基光催化剂在不同污染物去除方面的应用并展望了未来的发展前景和潜力。     

TiO2光催化剂掺杂改性的研究进展

TiO₂在利用光能和环保等领域具有重要应用前景。由于TiO₂具有较大禁带宽度，限制其对太阳光等可见光能的利用。通过对TiO₂掺杂改性，合成出具有较窄禁带宽度和稳定性好的光催化剂，促进光催化剂的实际应用。介绍了TiO₂光催化作用机理，从金属掺杂、非金属掺杂和共掺杂等方面总结TiO₂催化剂掺杂改性的研究现状。     

Mn1-xCuxO2/ reduced graphene oxide nanocomposites: Synthesis,characterization, and evaluation of visible light mediated catalytic studies

The narrow optical band gap, higher electrical conductivity, and wider-absorption range are three key features that a good photocatalyst must possess. Herein, we have fabricated Cu-doped MnO₂ (Mn_1-xCu_xO₂) nanostructure by facile wet chemical approach and formed its nanocomposite with r-GO (Mn_1-xCu_xO₂/r-GO) via ultra-sonication approach. The successful replacement of host metal ions (Mn⁴⁺) with the dopant metal ions (Cu²⁺) was supported with the PXRD, FT-IR, and EDX characterizations. The effect of Cu-doping on the band gap and r-GO matrix on the conductivity of the fabricated nanocomposite was also evaluated via Tauc plots and I–V tests, respectively. The photocatalytic efficiency of the fabricated photocatalysts was tested and compared against the methylene blue (MB) under visible light irradiation. The photocatalytic experiments revealed that Mn_1-xCu_xO₂/r-GO photocatalyst exhibited superior photocatalytic aptitude than that of pristine MnO₂ and Mn_1-xCu_xO₂ photocatalysts. More precisely, the Mn_1-xCu_xO₂ photocatalysts degraded 86.89% MB dye at the rate of 0.021 min^?1 after a 90-min exposure to the visible light. Observed superior catalytic activity of the nanocomposite can be attributed to the synergistic effects between the Cu doped MnO₂ and r-GO nanosheets that resulted in its narrow band-gap (2.19 eV) and excellent conductivity (2.217 × 10^?2 Scm^?1).     

二氧化钛可见光光催化剂研究进展

综述了二氧化钛可见光化的一些理论观点及其改性技术的新进展,涉及染料光敏化、金属离子掺杂、贵金属沉积和复合半导体、非金属掺杂等,认为二氧化钛可见光化中的改性,实际上是使催化剂产生靠近导带或价带的内带隙的过程,并且这个新形成的带隙能使催化剂对可见光产生有效的响应。针对二氧化钛光催化剂实用化中存在的问题,指出有效地抑制电子复合是今后改性研究的重点,寻找低成本的光敏物质或使污染物本身具有较好的光敏化性能是今后光敏化研究的方向之一。     

Modification of the band gap of Ruddlesden‒Popper perovskites Srn+1TinO3n+1 (n=1, 2, 3, and ∞) by Fe ion irradiation doping

Ruddlesden?Popper (RP)-type perovskite materials Sr_n+1Ti_nO_3n+1 (n = 1, 2, 3, and ∞) have important application prospects in photocatalysis. However, their wide band gap limits their visible light absorption ability. Doping is an efficient method that can be used to reduce the band gap and improve its light absorption range. In this work, irradiation doping with the advantages of compulsivity and controllability, rather than a chemical doping method, is used to manipulate the band gaps of Sr_n+1Ti_nO_3n+1 to understand the respective contributions of the substitution of the Sr and Ti sites to the band gap reduction as a function of the n value. The solid-state reaction-prepared RP-type perovskites Sr_n+1Ti_nO_3n+1 (n = 1, 2, 3, and ∞) irradiated by a 270 keV Fe ion beam with 0–1 × 10¹⁶ ions/cm² doses were characterized by SEM, XRD and UV–vis diffuse reflectance spectra. Tauc plot analysis showed that the band gaps of Sr_n+1Ti_nO_3n+1 decreased with an increase in Fe doping dose, which was confirmed by DFT calculations. Meanwhile, the effects of the perovskite and rock-salt layers of the RP-type perovskite on the band gap modification were demonstrated, showing that the band gap of Sr_n+1Ti_nO_3n+1 with smaller n values decreases less when the Fe irradiation dose increases. This is explained by more salt SrO layers found in Sr_n+1Ti_nO_3n+1 for smaller n values, which prevents the substitution of Sr and Ti atoms in perovskite layers, significantly influencing the band gap.     

高级氧化技术处理难降解有机废水的研发趋势及实用化进展

工业生产活动产生的难降解有机废水需要有效处理,否则对生态环境和人类健康造成极大危害。高级氧化技术具有处理速率快、降解效率高、适用范围广等优点,是处理难降解有机废水最具应用前景的方法之一。但目前高级氧化技术仍存在高耗能、高成本等缺点,为了降低处理成本,近年来,以高级氧化技术为主结合生物处理方法的耦合/复合处理技术得到广泛研究。在综述高级氧化法处理难降解有机废水最新技术如等离子体高级氧化法、太阳光催化氧化和Bio-electro-Fenton氧化法等的基础上,重点介绍了高级氧化法复合处理技术和高级氧化法与生物法耦合处理技术,并结合高级氧化技术实用化发展方向,总结了复合/耦合高级氧化技术扩大化处理实例。本文还对高级氧化技术的研究方向和实用化的前景进行了展望。     

First-principles study on transition metal-doped anatase TiO2

The electronic structures, formation energies, and band edge positions of anatase TiO₂ doped with transition metals have been analyzed by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The model structures of transition metal-doped TiO₂ were constructed by using the 24-atom 2 × 1 × 1 supercell of anatase TiO₂ with one Ti atom replaced by a transition metal atom. The results indicate that most transition metal doping can narrow the band gap of TiO₂, lead to the improvement in the photoreactivity of TiO₂, and simultaneously maintain strong redox potential. Under O-rich growth condition, the preparation of Co-, Cr-, and Ni-doped TiO₂ becomes relatively easy in the experiment due to their negative impurity formation energies, which suggests that these doping systems are easy to obtain and with good stability. The theoretical calculations could provide meaningful guides to develop more active photocatalysts with visible light response.     

Correlation of electrical properties and performance of OCM MOx/Na2WO4/SiO2 catalysts

The electrical conductivity and catalytic performance of MO_x/Na₂WO₄/SiO₂ catalysts in oxidative coupling of methane (OCM) are measured and correlated. M is V, Cr, Mn, Fe, Co or Zn. In this study, for the first time, the conductivity of the catalyst powder was measured under the OCM conditions as well as in oxygen. A definite correlation between the catalytic performance, the electrical conductivity under the OCM conditions, and the band gap of metal oxide constituent of the catalysts is observed. Manganese oxide (MnO_x with the lowest band gap) on Na₂WO₄SiO₂ with the highest electrical conductivity shows the best catalytic performance.     

One-pot synthesis of twist-like helix tungsten–nitrogen-codoped titania photocatalysts with highly improved visible light activity in the abatement of phenol

The twist-like helix W,N-codoped TiO₂ photocatalysts were prepared by a simple one-pot synthesis route to hydrolysis of titania tetrachloride using ammonium tungstate as tungsten and nitrogen sources. The morphology and microstructure characteristics of W,N-codoped titania photocatalysts with different amount of tungsten doping were characterized by means of BET, TEM, SEM, XPS, UV–vis DRS, PLS and XRD. The probable mechanism of codoping effect is proposed. It is presumed that cooperation of nitrogen and tungsten ions leads to produce new states and narrow the band gap between the valence band and conduction band effectively, which will greatly improve the photocatalytic activity in the visible light region. On the other hand, the tungsten ions with changing valences in the W,N-TiO₂ samples are considered to act as trapping sites, which will effectively decrease the recombination rate of photo-induced electrons and holes and then increase the photo-oxidation efficiency of the catalysts. The metal and nonmetal codoped 1%-W,N-TiO₂ sample shows the best photocatalytic activity, which is much superior to P25 under both visible and ultraviolet light irradiation. The superior activity of W,N-TiO₂ photocatalysts can also be ascribed to the special twist-like helix structure with regular holes on the wall, high surface area, large pore volume and well-crystallized anatase phase.     

碳基材料复合半导体光催化剂的制备及应用研究进展

半导体光催化剂被广泛地应用于光催化领域,但其常因自身的禁带宽度较大、量子效率较低、催化效率较低、与反应物接触几率较低等因素在实际应用中受到诸多限制。而碳基材料作为一类结构稳定的新材料,具有稳定性强、导电能力强、比表面积大、包含大量的吸附位点等特性,与光催化剂复合之后,能够有效减小其禁带宽度、降低其载流子的复合率并为其提供更多的吸附位点,很大程度上提高了光催化剂的光催化性能。该文章以石墨烯、碳纳米管、富勒烯以及碳纤维等碳材料与各类半导体光催化剂复合为例,综述了碳基材料与光催化剂复合的工艺、提高其光催化性能的机理、影响碳基材料改性程度的因素及其在产氢、杀菌等方面的应用,并且对其进行了展望。