基于三氧化钨的光阳极水氧化综述（英文）

光电催化水分解技术可以在分离的空间内分别进行水的还原和氧化反应生成氢气和氧气,是一种高效的光能到氢能的转换技术,因而受到研究者的广泛关注.光电催化水分解过程中,阳极上发生的水氧化反应是一个四电子转移过程,是水分解反应的限速步骤.为了提高光电催化水分解中阴极的产氢效率,应当优先提高阳极上的水氧化反应效率.在众多的光阳极中,三氧化钨由于其带隙窄和价带位置高而成为理想的光阳极材料之一.尽管如此,三氧化钨阳极的实际应用受到光生电子和空穴的严重复合以及电极表面缓慢反应动力学的限制.本文详细介绍了三氧化钨材料作为光阳极用于光电催化水氧化反应的优缺点,并从形貌控制、构造缺陷、构建异质结、负载助催化剂及应用等离子体效应等方面对提高三氧化钨阳极水氧化性能进行了综述.通过形貌控制可以增大电极的比表面积或降低材料的厚度,有利于光生电荷迁移到电极表面;在三氧化钨上引入适量的化学缺陷可以提供大量的反应位点,有利于光生电荷的传输;通过构建异质结可以有效促进三氧化钨电极内的光生电荷分离,提高整个复合电极的光吸收效率.如果构建异质结的另一种材料本身也是一种水氧化助催化剂,那么该材料可以起到分离光生电荷和提高表面催化效率的双重作用;负载助催化剂可以提高三氧化钨电极表面的反应活性,进而提高到达电极表面的光生电荷利用效率,得到提高的光电流和降低的起始电位;在三氧化钨电极上负载具有等离子效应的金属(如贵金属金、银等)可以提高电极的光电转换效率.光电催化水分解包含光的吸收、光生电荷分离和分离的光生电荷参与反应三个过程.只有当这三个过程的效率同时得到提高时,光电催化水分解的效率才能达到最高.尽管本文介绍的这些措施都可以提高三氧化钨电极的性能,但这些措施往往局限于从一个方面来提高电极性能.在未来的研究中,可以通过提高反应中的上述两个或三个过程的效率来实现三氧化钨电极更高的光电催化水氧化性能.

棒状金属有机框架结构PCN-222(Cu)/TiO2复合材料的制备及其高效光催化CO2还原性能

受环境污染和能源短缺的双重压迫,光催化CO2还原技术引起了人们的广泛关注。低成本光催化材料的开发对于实现有效的太阳能-燃料转换至关重要。TiO2作为光催化剂在光催化CO2还原中被广泛采用。然而,较宽的禁带宽度和光生载流子的复合限制了它的进一步应用。在这项工作中,我们使用棒状PCN-222(Cu)/TiO2复合材料作为光催化剂,使用简单的水热法报告了二氧化碳的光化学还原。经过对PCN-222(Cu)/TiO2进行一系列X射线衍射(XRD),扫描电子显微镜(SEM),紫外-可见漫反射光谱(DRS),傅里叶变换红外光谱(FT-IR),光电化学(PEC)和光致发光光谱(PL)等表征结果证明成功制备了该复合材料。SEM证实,TiO2颗粒均匀分布在棒状PCN-222(Cu)/TiO2的表面上。XRD结果表明,成功制备了具有良好晶体结构的PCN-222(Cu)和PCN-222(Cu)/TiO2复合光催化剂。DRS显示制备的PCN-222(Cu)/TiO2复合材料在可见光区域出现金属卟啉的特征吸收峰。PL和瞬态光电流响应和电化学阻抗谱(EIS)进一步证实了棒状PCN-222(Cu)/TiO2具有更好的电子-空穴对分离效率。通过控制PCN-222(Cu)和TiO2的质量比,经CO2还原性能测试表明,10%PCN-222(Cu)/TiO2复合材料具有最佳的催化活性。在氙灯照射下,棒状PCN-222(Cu)/TiO2表现出比TiO2纳米颗粒更好的光催化CO2活性,这归因于电荷传输和较好的电子-空穴分离能力。10%PCN-222(Cu)/TiO2复合材料的催化效率最高,产率分别为13.24μmol·g-1·h-1 CO和1.73μmol·g-1·h-1CH4。此外,经过三个循环的测试,PCN-222(Cu)/TiO2光催化剂的催化活性基本保持不变,在连续8小时光照下,催化剂的还原产率持续增加,表明PCN-222(Cu)/TiO2复合材料具有好的稳定性。禁带宽度和Mote-Schottky(M-S)曲线结果表明,PCN-222(Cu)的LUMO位比TiO2的导带(CB)更负,因此提出了PCN-222(Cu)/TiO2复合材料可能的光催化反应机理。该研究为金属有机骨架和氧化物半导体复合材料光催化体系提供了新的策略。

BiOCl0.9I0.1/β-Bi2O3复合材料在模拟太阳光下光催化降解盐酸四环素性能

盐酸四环素(TCH)是一种常见且广泛用于制药保健和兽医领域的抗生素,水生环境中的TCH残留物可诱导抗生素抗性病原体的发展,并对人类健康具有潜在的长期威胁.然而,传统的物理吸附和生物降解方法很难实现对TCH的降解.光催化技术由于其高效,简单的操作和低成本被认为是降解TCH的实用方法.Bi OX (X=Cl,Br和I)是具有间接带隙的半导体,其光生载流子的复合概率相对较低,因而在光催化中有着广泛应用.但是,当单独Bi OX作为光催化材料时,其电子-空穴对分离弱、载流子传输慢,从而使Bi OX不能很好的在光催化领域发挥作用.为了缓解或解决此限制性因素,将卤氧化物BiOCl0.9I0.1与半导体β–Bi2O3复合,通过在光照下降解20 mg·L–1的TCH来评价复合材料的光催化性能.基于此,本文采用电子扫描电镜(SEM)、高分辨透射电镜(HRTEM)、X射线衍射(XRD)、和电流时间(i–t)等对其进行了表征和活性测试,通过UV–vis漫反射光谱, Mott-Schottky图和XPS光谱,分析样品的相对VB和CB边缘位置和元素价态;通过能带评价,探讨了BiOCl0.9I0.1/15%β–Bi2O3在TCH降解过程中光催化活性的可能机理.SEM分析表明,纯BiOCl0.9I0.1样品是方形纳米片且尺寸约为100 nm,其规则地成形并层层覆盖.将制备的BiOCl0.9I0.1/15%β-Bi2O3复合物的基本形态与纯BiOCl0.9I0.1和纯β–Bi2O3进行比较,纯β–Bi2O3为块状结构,形成复合物后, BiOCl0.9I0.1纳米片作为组分嵌入β–Bi2O3块中, BiOCl0.9I0.1纳米片在β–Bi2O3表面部分聚集成最终覆盖整个表面的小花状微结构.BiOCl0.9I0.1纳米片的存在极大地增加了复合物的比表面积,并为反应提供了更多的活性位点.HRTEM表征结果进一步确认了上述结果.紫外漫反射吸收光谱表明,β-Bi2O3能有效增加BiOCl0.9I0.1对可见光的吸收,增加了对光的利用率.光催化性能测试表明在光照120 min后, BiOCl0.9I0.1/15%β–Bi2O3复合材料的样品中TCH的降解率达到了82.4%,而BiOCl0.9I0.1,β-Bi2O3, BiOCl0.9I0.1/5%β-Bi2O3, BiOCl0.9I0.1/10%β-Bi2O3和BiOCl0.9I0.1/20%β-Bi2O3等复合样品的TCH的降解率仅分别为54.8%, 21.0%, 70.0%, 73.2%和79.9%,说明BiOCl0.9I0.1/15%β-Bi2O3对水中的盐酸四环素有很好的降解作用.为了探索TCH光降解中涉及的活性物质,我们进行了一系列清除试验,得出TCH光降解的主要活性物质是·O2–和·OH.为了研究BiOCl0.9I0.1/x%β-Bi2O3复合催化剂的重复使用性能,将反应后的样品粉末收集,并在相同条件下重复使用三次.结果发现,BiOCl0.9I0.1/15%β-Bi2O3的光催化活性未见显著降低,表明它具有优异的稳定性和可再利用性.

铁基多相助催化剂光电化学水氧化研究进展

化石燃料的使用已经引起了严重的环境问题,例如空气污染和温室效应。同时,化石燃料作为不可再生能源无法一直满足人们不断的能源需求。因此,开发清洁可再生能源非常重要。氢是一种清洁无污染的可再生能源,可以缓解整个社会的能源压力。地球在一秒钟内接收到的太阳光能为1.7×10^(14) J,远远超过了人类一年的总能源消耗。因此,将太阳能转化为有价值的氢能对于减少对化石燃料的依赖具有重要的意义。自1972年藤岛昭和本多健一首次报道TiO_(2)光催化剂以来,人们发现半导体可以通过电或光驱动水分解产生清洁无污染的氢气。通过这种方式产氢不仅可以替代化石燃料,还可以提供环保的可再生氢能源,受到了人们的广泛关注。光电化学(PEC)水分解可以利用太阳能生产清洁、可持续的氢能。由于光阳极上的析氧反应(OER)缓慢,因此总的能量转换效率仍然很低,限制了PEC水分解的实际应用。助催化剂对于改善光电化学水分解性能是必要的。贵金属氧化物已被证明是最有效的OER催化剂,因为它们在酸性和碱性条件下具有很高的OER活性。然而,这些贵金属氧化物成本高和储量低,极大地限制了它们的实际应用。因此,开发高活性和低成本的OER助催化剂非常重要。迄今为止,对第一周期过渡金属(例如,Fe,Co,Ni和Mn)助催化剂的合成研究比较集中。其中,铁在地球上含量丰富,并且毒性比其他过渡金属低,使其成为良好的助催化剂。另外,铁基化合物具有半导体/金属的特性和独特的电子结构,可以改善材料的电导率和对水的吸附性能。目前,各种具有高催化活性的铁基催化剂已经被设计来提高光电化学的水氧化效率。本文简要概述了羟基氧化铁,铁基层状双氢氧化物和铁基钙钛矿等的结构、合成和应用方面的最新研究进展,并讨论了这些助催化剂在光电化学水氧化的性能。

Construction of TiO_(2)-covalent organic framework Z-Scheme hybrid through coordination bond for photocatalytic CO_(2) conversion

In this work,a covalent organic framework(COF),which is constructed by the building blocks of[5,10,15,20-tetrakis(4-aminophenyl)porphinato]copper(Ⅱ)(CuTAPP)and p-benzaldehyde,is employed to integrate with TiO_(2) for the purpose of establishing a Z-scheme hybrid.Within the system,isonicotinic acid performs the role of a bridge that connects the two components through a coordination bond.Further photocatalytic application reveals the hybrid framework is able to catalyze CO_(2) conversion under simulated solar light,resulting in CO production rate of 50.5 μmol g^(-1)·h^(-1),about 9.9 and 24.5 times that of COF and pristine TiO_(2),respectively.The ameliorated catalytic performance owes much to the por-phyrin block acting as photosensitizer that augments the light absorbance,and the establishment of Z-scheme system between the inorganic and orga nic comp on ents that enhances the separati on of the carriers.In addition,the chemical bridge also ensures a steady usage and stable charge delivery in the catalysis.Our study sheds light on the development of versatile approaches to covalently in corporate COFs with inorga nic semic on ductors.

In-situ incorporation of Copper （Ⅱ） porphyrin functionalized zirconium MOF and TiO2 for efficient photocatalytic CO2 reduction

As one of the highly effective methods to prepare catalysts for photocatalytic reduction of CO2 into valueadded chemicals,using metalloporphyrin as light-harvesting mixed ligand to modify metal-organic framework(MOF)is very valuable since it can greatly improve the prophyrin dispersibility and consequently inhibit its potential agglomeration.Herein,we employed a one-pot synthetic strategy to chemically immobilize Cu(II)tetra(4-carboxylphenyl)porphyrin(CuTCPP)into UiO-66 MOF structure through coordination mode.Meanwhile,in-situ growth of TiO2 nanoparticles onto the MOF is actualized with the generation of CuTCPP c UiO-66/TiO2(CTU/TiO2)composites.Under Xe lamp irradiation(λ>300 nm),the catalytic result presents that an optimal value of 31.32 μmol g^-1 h^-1 CO evolution amount,about 7 times higher than that of pure TiO2 was obtained through the photocatalysis.It is supposed owning to a consistent augment of light absorption derived from chemically implanted porphyrin derivative,which is simultaneously functioning with an efficacious separation of photo-induced carries given by the newly engendered composites between MOF and TiO2,an effective catalytic activity and approving recyclability of CTU/TiO2 can be achieved in the photocatalytic reduction of CO2 into CO.

Construction of ternary CuO/CuFe_(2)O_(4)/g-C_(3)N_(4)composite and its enhanced photocatalytic degradation of tetracycline hydrochloride with persulfate under simulated sunlight

In this study,a graphitic carbon nitride(g-C_(3)N_(4))based ternary catalyst Cu O/Cu Fe_(2)O_(4)/gC_(3)N_(4)(CCCN)is successfully prepared thorough calcination method.After confirming the structure and composition of CCCN,the as-synthesized composites are utilized to activate persulfate(PS)for the degradation of organic contaminant.While using tetracycline hydrochloride(TC)as pollutant surrogate,the effects of initial p H,PS and catalyst concentration on the degradation rate are systematically studied.Under the optimized reaction condition,CCCN/PS is able to give 99%degradation extent and 74%chemical oxygen demand removal in assistance of simulated solar light,both of which are apparently greater than that of either Cu O/Cu Fe_(2)O_(4)and pristine g-C_(3)N_(4).The great improvement in degradation can be assignable to the effective separation of photoinduced carriers thanks to the integration between Cu O/Cu Fe_(2)O_(4)and g-C_(3)N_(4),as well as the increased reaction sites given by the g-C_(3)N_(4)substrate.Moreover,the scavenging trials imply that the major oxidative matters involved in the decomposition are hydroxyl radicals(·OH),superoxide radicals(·O_(2)^(-))and photo-induced holes(h^(+)).

Research Progress of Ferrite Materials for Photoelectrochemical Water Splitting

Photoelectrochemical(PEC)water splitting is an effective strategy to convert solar energy into clean and renewable hydrogen energy.In order to carry out effective PEC conversion,researchers have conducted a lot of exploration and developed a variety of semiconductors suitable for PEC water splitting.Among them,metal oxides stand out due to their higher stability.Compared with traditional oxide semiconductors,ferrite-based photoelectrodes have the advantages of low cost,small band gap,and good stability.Interestingly,due to the unique characteristics of ferrite,most of them have various tunable features,which will be more conducive to the development of efficient PEC electrode.However,this complex metal oxide is also troubled by severe charge recombination and low carrier transport efficiency,resulting in lower conversion efficiency compared to theoretical value.Based on this,this article reviews the structure,preparation methods,characteristics and modification strategies of various common ferrites.In addition,we analyzed the future research direction of ferrite for PEC water splitting,and looked forward to the development of more efficient catalysts.

In situ conversion builds MIL-101@NiFe-LDH heterojunction structures to enhance the oxygen evolution reaction

The construction of rich phase interfaces to increase active reaction area in hybrid materials is an excellent strategy to improve electrochemical performance.Under this guideline,MIL-101@OX-metal organic framework(MOF)is constructed by the"MOF on MOF"method,then converts to MIL-101@NiFe-layered double hydroxides(LDH)by in situ transformation in alkaline solution.MIL-101@NiFe-LDH shows excellent electrochemical water oxidation performance.It needs only an overpotential of 215 m V to drive10 m A/cm^(2)of oxygen evolution reaction(OER),which is less than that of NiFe-LDH,MIL-101.In addition,MIL-101@NiFe-LDH has the smallest Tafel slope(55.1 mV/dec)compared with Ni Fe-LDH(61.1 m V/dec),MIL-101(150.8 m V/dec).The excellent water oxidation activity is due to the high phase interfaces derived from high specific surface area of MOF.This work offers an alternative method for making MOF/LDH heterostructures with an optimized phase interfaces and provides new insights for OER.

Enhanced performance of NiF_(2)/BiVO_(4)photoanode for photoelectrochemical water splitting

The serious surface charge recombination and fatigued photogenerated carriers transfer of the BiVO_(4)photoanode restrict its photoelectrochemical(PEC)water splitting performance.In this work,nickel fluoride(NiF_(2))is applied to revamp pure BiVO_(4)photoanode by using a facile electrodeposition method.As a result,the asprepared NiF_(2)/BiVO_(4)photoanode increases the dramatic photocurrent density by approximately 180%compared with the pristine BiVO_(4)photoanode.Furthermore,the correlative photon-to-current conversion efficiency,the charge injection,and the separation efficiency,as well as the hydrogen generation of the composite photoanode have been memorably enhanced due to the synergy of NiF_(2)and BiVO_(4).This study may furnish a dependable guidance in fabricating the fluoride-based compound/semiconductor composite photoanode system.