镧系离子掺杂的近红外复合光催化剂的合成研究进展

近红外光能量占太阳能的44%,但是传统半导体光催化剂难以利用近红外光,因此制备近红外光催化剂是近几年来的研究热点。本文阐述了镧系离子掺杂的近红外光催化剂催化的基本原理,综述了镧系离子掺杂上转换纳米材料/半导体复合近红外光催化剂的合成方法及特点,重点介绍了外延生长法,静电纺丝法与化学组装法。并对这些近红外光催化材料在光降解污染物和光解水领域的应用进行了总结并对其应用前景进行了展望。     

镧系离子掺杂TiO2的制备及其对咪唑降解反应的光催化活性

 以TiCl4和镧系元素的氯化盐溶液为前驱体,采用溶胶-凝胶法制备了不同含量镧系离子掺杂的TiO2光催化剂,用X射线衍射(XRD)、 光致发光光谱(PLS)、 表面光电压谱(SPS)和X射线光电子能谱(XPS)对催化剂进行了表征. XRD结果表明,样品为锐钛矿和金红石的混晶相,镧系离子未进入到TiO2晶格中. PLS和SPS测定结果表明,随着掺杂离子的不同和掺杂含量的不同,样品的谱强度呈现有规律的变化. 在紫外光照射下,以咪唑为目标降解物比较了催化剂的光催化活性. 结果表明,适当含量的镧系离子掺杂可有效促进TiO2表面光生载流子的分离,从而显著提高其光催化活性.     

Ce掺杂对La1-xCexCoO3催化剂的结构和催化氧化性能的影响

采用非晶态配合物的方法合成了La1-xCexCoO3(x=0、0.05、0.1、0.2、0.3)催化剂, 并采用X射线衍射(XRD)、透射电镜(TEM)和比表面测定仪(BET)等手段对催化剂的微观结构进行了研究. 揭示了Ce掺杂对催化剂的钙钛矿结构, CO催化氧化以及催化氧化发光性能的影响规律. 结果表明, 在Ce4+掺杂部分取代La3+后, 催化剂形成了镧不足的La1-xCeyφx-yCoO3(φ是A位离子空位)钙钛矿相以及CeO2和Co3O4物相. 与LaCoO3催化剂相比, x=0.1催化剂的CO催化氧化活性最高(T100%=290 ℃). La1-xCexCoO3催化剂对CO催化氧化发光的响应与其催化活性密切相关.     

利用镧系离子掺杂延长{001}/{101}晶面共暴露的TiO_2纳米片电荷分离态以增强其光催化产氢性能（英文）

随着工业化的快速发展,化石燃料等不可再生能源的快速消耗,人类将面临不可预测的能源危机.寻找有效的方法来解决能源短缺问题已成为当今的重要研究课题.氢能是一种可以替代化石燃料的清洁可再生能源.利用半导体光催化分解水制氢技术可以将太阳能转化为氢能.目前,在已开发的半导体光催化材料中, TiO_2因具有无毒、稳定、廉价等优点而备受光催化领域关注.但是,在实际应用方面, TiO_2的光催化效率受限于其低的光子利用率和较高的光生电子-空穴复合率.许多研究表明, TiO_2不同晶面的协同作用有利于光生载流子的迁移分离,并且适量的掺杂能够捕获光生电子,从而抑制其复合.而镧系元素因其特殊4f电子结构受到广泛的关注.采用物理或化学方法将镧系离子引入TiO_2晶格中,可以影响光生电子和空穴的动力学过程,延长光生载流子的分离状态,从而提高光催化活性.本文通过简单溶剂热法成功合成了镧系离子掺杂{001}/{101}面共暴露的TiO_2纳米片.X-射线粉末衍射(XRD)、X-射线光电子能谱(XPS)和高分辨透射电子显微镜(HRTEM)的表征结果证明了镧系离子选择性掺杂在TiO_2纳米片{101}面上.结合紫外可见吸收光谱、稳态荧光、瞬态荧光衰减曲线、光电流及莫特-肖特基曲线等手段对镧系离子掺杂TiO_2光催化剂进行了表征,结果表明,镧系离子掺杂TiO_2纳米片增强了对光的吸收,同时延长光生载流子的分离状态,阻碍光生电子和空穴的复合.考察其光催化分解水制氢的性能.研究表明,在相同掺杂量(0.5 mol%RE~(3+)=Ho~(3+), Er~(3+), Tm~(3+), Yb~(3+), Lu~(3+))的TiO_2纳米片中, Yb~(3+)-TiO_2纳米片光催化剂具有优异的产氢活性,在模拟太阳光照射1 h后产氢量是纯TiO_2的4.25倍.同时讨论了不同浓度助催化剂Pt作用下的Yb~(3+)-TiO_2纳米片产氢效果,当Pt含量量为0.3wt%时,光解水产氢活性最佳, Pt/Yb~(3+)-TiO_2纳米片的产氢量是Yb~(3+)-TiO_2的2倍,纯TiO_2的8.5倍.光催化分解水产氢活性的显著提高可以归因于光生电子-空穴对在TiO_2纳米片{001}/{101}面的快速分离,以及镧系离子4f电子轨道对电子的捕获和杂质能级的产生减小了禁带宽度,这不仅延长了光生载流子的分离状态,增加了H~+还原成H_2的机会,而且还可以拓展可见光的吸收范围.可见,利用镧系离子掺杂TiO_2和共暴露{001}/{101}面协同作用是一种实现TiO_2基光催化活性提高的有效方法之一.镧系离子掺杂的策略对提高半导体纳米材料的光催化活性有显著的影响,可能在光催化、光电化学和太阳能电池领域有更广泛的应用.     

不同离子掺杂对镧六铝酸盐催化剂结构及其甲烷燃烧性能的影响

采用反相微乳液-共沉淀法制备了镧系六铝酸盐催化剂。体系中TX-100 作为表面活性剂,正己醇作为助表面活性剂,环己烷作为油相。分别用Fe、Co、Ni、Cu、Mg离子作为活性组分进行掺杂。通过X射线衍射、比表面积分析和扫描电镜等实验技术及甲烷燃烧对催化剂的结构和性质进行考察。结果表明,Fe离子和Mn离子共同掺杂所制备的催化剂LaMnFeAl₁0O₁9-δ具有较高的催化活性,起燃温度T₁0%为477℃,至674℃ 90%甲烷转化。     

稀土纳米材料在光催化二氧化碳还原中的应用

光催化二氧化碳还原反应(光催化CO₂RR)是将惰性CO₂转化为高价值化学品的最具前景的策略之一。光催化CO₂RR的成功取决于高效催化剂的使用,尽管目前已取得相当的进展,但光催化过程仍面临着光电效应弱和光生载流子易复合等问题,严重制约了CO₂还原的效率。稀土离子具有独特的f电子结构和尤其丰富的电子能级,可作为光生电子的“储存器”并兼具抑制光生载流子复合的功能,因此电子能更有效地用于CO₂RR。镧系金属离子的强亲氧性和高配位需求,使其易于掺杂进其他氧化物半导体的晶格中,不仅能够稳定半导体复合物的晶相,而且能够有效地调控氧空位的浓度,从而实现半导体光催化剂性能调控和优化。此外,镧系金属亦能以原子级分散方式吸附在半导体表面或实现体相掺杂,直接作为活性位点提升光生电子的传递与利用。本文总结和探讨了稀土纳米材料在光催化CO₂RR反应中的不同作用形式,从包括单(纯)稀土半导体材料、负载助催化剂的稀土半导体材料、掺杂稀土半导体材料和稀土半导体-其他半导体的复合材料等四方面...     

镧掺杂ZnO/TiO2催化降冰片二烯异构化反应研究

采用共沉淀法制备了ZnO／TiO2和La离子掺杂La-ZnO／TiO2催化剂,利用XRD,XPS和uV-vis对催化剂进行了表征;在光反应器中进行了ZnO/TiO2和La-znO／TiO2催化降冰片二烯光异构化生成四环烷的反应。研究了ZnO和La离子掺杂对催化剂的结构、表面组成、吸光性能及催化性能的影响。结果表明,ZnO/TiO2复合可形成锐钛矿和ZnTiO3混晶结构,从而提高了催化剂的活性;La离子掺杂能提高表面Ti-OH物种含量和催化剂的吸光性能,并提高ZnO／Ti02的催化活性。10％La掺杂的ZnO／TiO2催化活性最佳,反应12h四环烷的收率达93．58％,选择性为100％。当La的掺杂量达到30％时,催化剂中Ti-OH含量明显减少,吸光强度最低,活性下降。     

Catalytic combustion of toluene over manganese-substituted hexaaluminate catalysts

采用共沉淀法制备了系列锰掺杂六铝酸镧LaMnxAl12-xO19催化剂.XRD表征发现,只有在锰掺杂量为2.0 ～2.5时,经1 200℃焙烧处理得到的催化剂中才有完整的六铝酸盐晶相.由UV-vis漫反射、H2-TPR和BET比表面积分析表明,掺杂的锰离子主要以Mn3+形式取代六铝酸盐八面体位置的Al;同时随锰掺杂量增多,催化剂中Mn3+/Mn2+比例变大,而比表面积却相应减小.O2-TPD表征也进一步发现,随锰掺杂量增多,催化剂上化学吸附晶格氧量增加,而物理吸附氧分子量减少.在甲苯催化燃烧净化反应中,锰掺杂六铝酸镧催化剂表现出良好的低温催化活性,且锰掺杂量为2.0～2.5时活性最优.推测该反应是遵循Mars- van Krevelen机理,由Mn3+和Mn2+的协同作用共同促进晶格氧的流动性.     

掺钴固体超强酸SO_4~(2-)/SnO_2的制备和结构表征

掺杂钴对固体超强酸SO42-/SnO2进行改性,将其应用于乙酸和正丁醇的酯化反应,考察制备条件(钴离子浓度和焙烧温度)对催化性能的影响,发现引入一定浓度的钴离子能提高催化剂在酯化反应中的活性,在焙烧温度为500℃时,催化剂具有较高的活性;利用傅里叶红外光谱、X射线衍射、热重差热分析等测试手段对催化剂酸性、晶型和活性组分含量进行研究。     

钙铝掺杂镧锰钙钛矿高效催化剂用于两步法热化学分解水取得出色产氢表现

太阳能热化学分解水是一种高效生产清洁和可再生氢能源的方法.由于出色的催化活性和太阳能燃料生产能力,钙钛矿型的催化剂在热化学领域引起了强烈关注.我们采用改良的Pechini法合成了一系列钙铝掺杂的镧锰钙钛矿并系统考察了其在两步法热化学分解水中的产氢表现.为了优化热化学催化性能,我们进行了镧锰钙钛矿A,B位上钙和铝的掺杂量(从0.2到0.8)的详细考察.通过调整掺杂比例,得到了一种极其高效的钙钛矿催化剂La0.6Ca0.4Mn0.6Al0.4O3.当两步法热化学分解水在1400和1000℃之间,La0.6Ca0.4Mn0.6Al0.4O3取得了429μmol/g的出色产氢表现,比同等条件下基准催化剂氧化铈产氢结果高出8倍.与此同时,钙铝掺杂镧锰钙钛矿在两步法热化学循环测试中展现出极其稳定的催化活性.因此,这种新颖的钙铝掺杂镧锰钙钛矿具备巨大的潜质用于未来热化学太阳能燃料的实际生产.     

Exploiting Reusable Edge-Functionalized Metal-Free Polyphthalocyanine Networks for Efficient Polymer Synthesis at Near Infrared Wavelengths

Heterogeneous catalysts are highly advantageous for industrial applications owing to their distinctive merits including easy separation and effective recovery. However, utilizing heterogeneous photocatalysts to harness longer wavelength light remains a critical area of research. This contribution explores the use of edge-functionalized metal-free polyphthalocyanine networks (PPc-x) to promote efficient polymer synthesis under near infrared (NIR) light irradiation. Our screening process revealed that both phenyl-edged PPc-x (PPc-p) and naphthyl-edged PPc-x (PPc-n) offer promising performance for photopolymerization. With the assistance of ppm-level PPc-n catalyst, well-defined polymers were synthesized within a few hours under the regulation of three NIR lights, regardless of shielded by synthetic and biological barriers. An excellent control over the molecular weight and molecular weight distribution was achieved. Furthermore, PPc-x can be easily recovered and reused for multiple cycles, with negligible leaching and maintenance of the catalytic performance. This study expands a new avenue in developing versatile photocatalysts for the modern synthetic toolkits and offer benefits in diverse applications.     

Noncontinuous Super‐Diffusive Dynamics of a Light‐Activated Nanobottle Motor

We report a carbonaceous nanobottle (CNB) motor for near infrared (NIR) light‐driven jet propulsion. The bottle structure of the CNB motor is fabricated by soft‐template‐based polymerization. Upon illumination with NIR light, the photothermal effect of the CNB motor carbon shell causes a rapid increase in the temperature of the water inside the nanobottle and thus the ejection of the heated fluid from the open neck, which propels the CNB motor. The occurrence of an explosion, the on/off motion, and the swing behavior of the CNB motor can be modulated by adjusting the NIR light source. Moreover, we simulated the physical field distribution (temperature, fluid velocity, and pressure) of the CNB motor to demonstrate the mechanism of NIR light‐driven jet propulsion. This NIR light‐powered CNB motor exhibits fuel‐free propulsion and control of the swimming velocity by external light and has great potential for future biomedical applications.     

Near Infrared Light-to-Heat Conversion for Liquid-Phase Oxidation Reactions by Antimony-Doped Tin Oxide Nanocrystals

Effective utilization of the sunlight for chemical reactions is pivotal for dealing with the growing energy and environmental issues. So far, much effort has been focused on the development of semiconductor photocatalysts responsive to UV and visible light. However, the near infrared and infrared (NIR-IR) light occupying ∼50 % of the solar energy has usually been wasted because of the low photon energy insufficient for the band gap excitation. Antimony doping into SnO₂ (ATO) induces strong absorption due to the conduction band electrons in the NIR region. The absorbed light energy is eventually converted to heat via the interaction between hot electrons and phonons. This Concept highlights the photothermal effect of ATO nanocrystals (NCs) on liquid-phase oxidation reactions through the NIR light-to-heat conversion. Under NIR illumination even at an intensity of ∼0.5 sun, the reaction field temperature on the catalyst surface is raised 20–30 K above the bulk solution temperature, while the latter is maintained near the ambient temperature. In some reactions, this photothermal local heating engenders the enhancement of not only the catalytic activity and selectivity but also the regeneration of catalytically active sites. Further, the photocatalytic activity of semiconductors can be promoted. Finally, the conclusions and possible subjects in the future are summarized.     

Dynamic Modulation of Enzyme Activity by Near‐Infrared Light

Engineering near‐infrared (NIR) light‐sensitive enzymes remains a huge challenge. A photothermal effect‐associated method is developed for tailoring the enzymatic activity of enzymes by exposure to NIR light. An ultrasmall platinum nanoparticle was anchored in an enzyme to generate local heating upon NIR irradiation, which enhanced the enzyme activity without increasing bulk temperature. Following NIR irradiation, the enzyme activity was tailored rapidly and reversibly, and was modulated by varying laser power density and irradiation time. Four enzymes were engineered, including glucoamylase, glucose oxidase, catalase, and proteinase K with NIR‐light sensitivity, and demonstrated their utility in practical applications such as photolithography and NIR light‐responsive antibacterial or anticancer actions. Our investigation suggests that this approach could be broadly used to engineer enzymes with NIR‐light sensitivity for many biological applications.     

Naked‐Eye Readout of Analyte‐Induced NIR Fluorescence Responses by an Initiation–Input–Transduction Nanoplatform

Fluorescence visualization (FV) in the near‐infrared (NIR) window promises to break through the signal‐to‐background ratio (SBR) bottleneck of traditional visible‐light‐driven FV methods. However, straightforward NIR‐FV has not been realized, owing to the lack of methods to readily transduce NIR responses into instrument‐free, naked eye‐recognizable outputs. Now, an initiation–input–transduction platform comprising a well‐designed NIR fluorophore as the signal initiator and lanthanide‐doped nanocrystals as the transducer for facile NIR‐FV is presented. The analyte‐induced off–on NIR signal serves as a sensitizing switch of transducer visible luminescence for naked‐eye readout. The design is demonstrated for portable, quantitative detection of phosgene with significantly improved SBR and sensitivity. By further exploration of initiators, this strategy holds promise to create advanced NIR‐FV probes for broad sensing applications.     

Quantum Defects as a Toolbox for the Covalent Functionalization of Carbon Nanotubes with Peptides and Proteins

Single‐walled carbon nanotubes (SWCNTs) are a 1D nanomaterial that shows fluorescence in the near‐infrared (NIR, >800 nm). In the past, covalent chemistry was less explored to functionalize SWCNTs as it impairs NIR emission. However, certain sp³ defects (quantum defects) in the carbon lattice have emerged that preserve NIR fluorescence and even introduce a new, red‐shifted emission peak. Here, we report on quantum defects, introduced using light‐driven diazonium chemistry, that serve as anchor points for peptides and proteins. We show that maleimide anchors allow conjugation of cysteine‐containing proteins such as a GFP‐binding nanobody. In addition, an Fmoc‐protected phenylalanine defect serves as a starting point for conjugation of visible fluorophores to create multicolor SWCNTs and in situ peptide synthesis directly on the nanotube. Therefore, these quantum defects are a versatile platform to tailor both the nanotube's photophysical properties as well as their surface chemistry.     

Near‐Infrared‐Light‐Driven Artificial Photosynthesis by Nanobiocatalytic Assemblies

Artificial photosynthesis in nanobiocatalytic assemblies aims to reconstruct man‐made photosensitizers, electron mediators, electron donors, and redox enzymes for solar synthesis of valuable chemicals through photochemical cofactor regeneration. Herein, we report, for the first time, on nanobiocatalytic artificial photosynthesis in near‐infrared (NIR) light, which constitutes over 46% of the solar energy. For NIR‐light‐driven photoenzymatic synthesis, we synthesized silica‐coated upconversion nanoparticles, Si‐NaYF4:Yb,Er and Si‐NaYF4:Yb,Tm, for efficient photon‐conversion through Förster resonance energy transfer (FRET) with rose bengal (RB), a photosensitizer. We observed NIR‐induced electron transfer by using linear sweep voltammetric analysis; this indicates that photoexcited electrons of RB/Si‐NaYF4:Yb,Er are transferred to NAD+ through a Rh‐based electron mediator. RB/Si‐NaYF4:Yb,Er nanoparticles, which exhibit higher FRET efficiency due to more spectral overlap than RB/Si‐NaYF4:Yb,Tm, perform much better in the photoenzymatic conversion.     

Surface Plasmon Resonance‐Enhanced Visible‐NIR‐Driven Photocatalytic and Photothermal Catalytic Performance by Ag/Mesoporous Black TiO2 Nanotube Heterojunctions

Ag/mesoporous black TiO₂ nanotubes heterojunctions (Ag‐MBTHs) were fabricated through a surface hydrogenation, wet‐impregnation and photoreduction strategy. The as‐prepared Ag‐MBTHs possess a relatively high specific surface area of ≈85 m² g^?1 and an average pore size of ≈13.2 nm. The Ag‐MBTHs with a narrow band gap of ≈2.63 eV extend the photoresponse from UV to the visible‐light and near‐infrared (NIR) region. They exhibit excellent visible‐NIR‐driven photothermal catalytic and photocatalytic performance for complete conversion of nitro aromatic compounds (100 %) and mineralization of highly toxic phenol (100 %). The enhancement can be attributed to the mesoporous hollow structures increasing the light multi‐refraction, the Ti³⁺ in frameworks and the surface plasmon resonance (SPR) effect of plasmonic Ag nanoparticles favoring light‐harvesting and spatial separation of photogenerated electron–hole pairs, which is confirmed by transient fluorescence. The fabrication of this SPR‐enhanced visible‐NIR‐driven Ag‐MBTHs catalyst may provide new insights for designing other high‐performance heterojunctions as photocatalytic and photothermal catalytic nanomaterials.