Sustainable Furfural Biomass Feedstocks Electrooxidation toward Value-Added Furoic Acid with Energy-Saving H_(2) Fuel Production Using Pt-Decorated Co_(3)O_(4) Nanospheres

Here,furfural oxidation was performed to replace the kinetically sluggish O_(2)evolution reaction(OER).Pt-Co_(3)O_(4)nanospheres were developed via pulsed laser ablation in liquid(PLAL)in a single step for the paired electrocatalysis of an H_(2)evolution reaction(HER)and furfural oxidation reaction(FOR).The FOR afforded a high furfural conversion(44.2%)with a major product of 2-furoic acid after a 2-h electrolysis at 1.55 V versus reversible hydrogen electrode in a 1.0-M KOH/50-mM furfural electrolyte.The Pt-Co_(3)O_(4)electrode exhibited a small overpotential of 290 mV at 10 mA cm^(-2).As an anode and cathode in an electrolyzer system,the Pt-Co_(3)O_(4)electrocatalyst required only a small applied cell voltage of~1.83 V to deliver 10 mA cm^(-2),compared with that of the pure water electrolyzer(OER||HER,~1.99 V).This study simultaneously realized the integrated production of energy-saving H_(2)fuel at the cathode and 2-furoic acid at the anode.

Mass Transfer-Promoted Fe^(2+)/Fe^(3+)Circulation Steered by 3D Flow-Through Co-Catalyst System Toward Sustainable Advanced Oxidation Processes

Realizing fast and continuous generation of reactive oxygen species(ROSs)via iron-based advanced oxidation processes(AOPs)is significant in the environmental and biological fields.However,current AOPs assisted by co-catalysts still suffer from the poor mass/electron transfer and non-durable promotion effect,giving rise to the sluggish Fe^(2+)/Fe^(3+)cycle and low dynamic concentration of Fe^(2+)for ROS production.Herein,we present a three-dimensional(3D)macroscale co-catalyst functionalized with molybdenum disulfide(MoS_(2))to achieve ultra-efficient Fe^(2+)regeneration(equilibrium Fe^(2+)ratio of 82.4%)and remarkable stability(more than 20 cycles)via a circulating flow-through process.Unlike the conventional batch-type reactor,experiments and computational fluid dynamics simulations demonstrate that the optimal utilization of the 3D active area under the flow-through mode,initiated by the convectionenhanced mass/charge transfer for Fe^(2+)reduction and then strengthened by MoS_(2)-induced flow rotation for sufficient reactant mixing,is crucial for oxidant activation and subsequent ROS generation.Strikingly,the flow-through co-catalytic system with superwetting capabilities can even tackle the intricate oily wastewater stabilized by different surfactants without the loss of pollutant degradation efficiency.Our findings highlight an innovative co-catalyst system design to expand the applicability of AOPs based technology,especially in large-scale complex wastewater treatment.

高热稳定性近红外荧光粉BaY_(2)Al_(2)Ga_(2)SiO_(12):Cr^(3+)的合成及发光性质

近年来,近红外荧光粉转换发光二极管(NIR pc-LED)在夜视、生物成像和无损检测等领域引起了广泛关注。然而,获得兼具高量子效率和优异热稳定性的近红外荧光粉仍然是一个巨大挑战。本文利用高温固相法合成了一种新型近红外荧光粉BaY_(2)Al_(2)Ga_(2)SiO_(12):Cr^(3+)(BYAGSO:Cr^(3+)),并系统研究了材料的结构和发光性质。在440 nm蓝光激发下,BYAGSO:Cr^(3+)荧光粉的发射光谱在650~850 nm范围内呈现锐线和宽带的混合发射,源于Cr^(3+):^(2)E→^(4)A_(2)自旋禁戒跃迁和^(4)T_(2)→^(4)A_(2)自旋允许跃迁发射。该近红外发光表现出可观的量子效率和良好的热稳定性,最优化样品的外量子效率可达30.3%,在200℃时样品的发光强度可保持其在室温时强度的99%。通过将BYAGSO:Cr^(3+)荧光粉与450 nm蓝光LED芯片结合,我们封装了一个NIR pc‐LED器件。该器件在300m A驱动电流下,输出功率为70.83 mW;在20m A驱动电流下,光电转换效率为11.20%。研究结果表明,BY-AGSO:Cr^(3+)在NIR pc-LED领域具有良好的应用前景。

Cr^(3+)掺杂的宽带近红外荧光粉研究进展

荧光转换型近红外发光二极管(NIR pc-LED)具有体积小、谱带宽和峰位易调谐等优点,是新一代NIR光源发展的前沿,其关键在于研发可被蓝光有效激发的高效率宽带近红外荧光粉。面向广泛研究的Cr^(3+)激活近红外发光材料,本文综述了发射峰在800~900 nm波段材料发展现状。基于磷酸盐、硼酸盐和硅锗酸盐等体系,阐述了其结构特征与近红外发光峰位、谱带宽度的关系,以及采用工艺优化、组分调节和共掺杂等方法调控近红外发光效率、热稳定性能的效果。

李氏禾内生细菌Bacillus cereus J01吸附Cr^(3+)的研究

为考察李氏禾内生细菌蜡样芽孢杆菌Bacillus cereus J01菌株吸附Cr^(3+)的性能,以蜡样芽孢杆菌Bacillus cereus J01失活菌体作为生物吸附剂,采用单因素实验方法考察pH、温度、Cr^(3+)初始浓度、吸附剂用量、吸附时间等条件对Cr^(3+)吸附性能的影响,分析其等温吸附过程、动力学过程及热力学过程,并采用红外光谱方法对吸附机理进行初步分析。结果表明:(1)在50 mL反应体系中,当pH值为6、温度为40℃、Cr^(3+)初始浓度为150 mg·L^(-1)、吸附剂投加量为0.2 g、吸附时间为12 h时,蜡样芽孢杆菌Bacillus cereus J01失活菌体对Cr^(3+)的吸附性能达到最佳,其平衡吸附量和Cr^(3+)去除率分别为34.30 mg·g^(-1)、91.60%。(2)等温吸附过程分析结果显示,朗格缪尔吸附等温模型能更好地模拟蜡样芽孢杆菌Bacillus cereus J01失活菌体对Cr^(3+)的吸附,其吸附过程更倾向于单分子层吸附。(3)吸附过程动力学分析结果显示,蜡样芽孢杆菌Bacillus cereus J01失活菌体对Cr^(3+)的吸附更符合准二级动力学速率方程。(4)吸附过程热力学分析结果显示,在40℃下,吸附过程的△G、△H和△S分别为-2.609 kJ·mol^(-1)、61.792 kJ·mol^(-1)和206.11 J·mol^(-1),该温度下吸附过程是自发过程。(5)红外光谱分析结果显示,蜡样芽孢杆菌Bacillus cereus J01失活菌体对Cr^(3+)的吸附可能通过细胞成分中的氨基、羟基和羰基起作用。该研究结果表明该菌的失活菌体对Cr^(3+)具有较强的吸附性能,并在铬污染的环境治理中具有较好的应用潜力。

Li(Sc,M)Si_(2)O_(6)∶Cr^(3+)(M=Ga^(3+)/Lu^(3+)/Y^(3+)/Gd^(3+))的近红外发光性能

荧光转换型近红外发光二极管(NIR pc-LED)具有体积小、谱带宽、峰位易调谐等优点,是新一代NIR光源发展的前沿,其关键在于研发可被蓝光有效激发的高效率宽带近红外荧光粉。LiScSi_(2)O_(6)∶Cr^(3+)荧光材料的激发波长为460 nm,发射峰位在845 nm,光谱带宽为156 nm,内量子效率为64.4%。基于该体系,本文通过M离子(M=Ga^(3+),Lu^(3+),Y^(3+),Gd^(3+))取代Sc^(3+)的方式对其性能进行调控。结果表明,引入M离子易生成杂相或发生相变,降低了材料的发光性能。本文从晶体结构出发对其调控过程进行了分析。

多格位阳离子共掺提升LiScSi_(2)O_(6)∶Cr^(3+)近红外荧光粉的光吸收

采用高温固相法制备Na^(+)、In^(3+)、Ge^(4+)单掺或共掺杂的LiScSi_(2)O_(6)∶Cr^(3+)荧光粉,通过漫反射光谱、光致激发和发射光谱、量子效率测试等手段对其光吸收及光致发光性能进行了研究。实验结果表明,Na^(+)、In^(3+)、Ge^(4+)等离子单独掺杂均可提升LiScSi_(2)O_(6)∶Cr^(3+)荧光粉对460 nm蓝光的吸收,而多格位阳离子共掺可进一步增强光吸收能力,吸收效率可从最初的50.5%提升至60.9%。多格位离子单掺或共掺引起Cr^(3+)占据八面体结构畸变程度增加,从而导致光吸收增强。优化荧光体系LiSc_(0.4)In_(0.6)Si_(1.6)Ge_(0.4)O_(6)∶Cr^(3+)的近红外发射峰波长为860 nm,半高宽为160 nm,内、外量子效率分别为72.5%和41.8%,封装制成的荧光转换型LED器件在100 mA驱动电流下近红外光输出功率为63.1 mW,近红外电光转换效率为22.3%,表现出较好的近红外发光综合性能。本研究工作为增强Cr^(3+)激活近红外荧光粉的光吸收提供了一种有效手段。

激活剂间隙位占据诱导氟化物NaHF_(2)∶Cr^(3+)的高效近红外发光

宽带近红外荧光粉转换型发光二极管(pc-LED)作为一种新型固态光源,在夜视照明、食品检测、生物成像等领域受到了广泛的关注。然而,如何实现高效的近红外发射仍然是一个巨大的挑战。本文采用水热法制备了氟化物近红外荧光粉NaHF_(2)∶Cr^(3+),发射峰位于761 nm,半高全宽约为112 nm,其内/外量子效率(IQE/EQE)为72.20%和29.6%。密度泛函理论(DFT)计算和晶体结构分析表明,Cr^(3+)离子在NaHF2体系中占据间隙位点,形成了高度畸变的八面体[CrF_(6)],有利于解除部分宇称禁阻跃迁,使得该荧光粉具有较高的发光效率。将荧光粉NaHF_(2)∶Cr^(3+)与蓝光InGaN芯片相结合,制备了近红外输出功率为426.74 mW@300 mA的pc-LED器件,在夜视成像等领域具有一定的应用前景。本研究也为设计高效近红外发射的Cr^(3+)激活荧光粉提供了新思路。

F/O阴离子取代调控ZnGa_(2)O_(4):Cr^(3+)近红外发光

采用高温固相法制备了一系列ZnGa_(2)O_(4):xCr^(3+),yMgF_(2)荧光粉,并研究其物相结构和发光性能。结果表明,MgF_(2)掺杂起主导作用的是F离子,F/O阴离子取代形成局域环境不同的[CrO_(6)]和[Cr(O,F)_(6)]发光中心,使ZnGa_(2)O_(4):Cr^(3+)发光谱显著宽化。进而通过增加Cr^(3+)浓度使发射谱不断红移,实现了峰值波长689~900nm波段可调发光;稳/瞬态光谱学分析表明谱峰大幅红移来自于不同Cr^(3+)发光中心间的能量传递。优化样品ZnGa_(2)O_(4):0.1Cr^(3+),0.2MgF_(2)(ZMGOF∶0.1Cr^(3+))表现出较好的综合性能,蓝光激发下宽带近红外发射覆盖700~1200nm波段,峰值波长885nm、半高宽215nm;且具有较为优异的发光效率和热稳定性,内、外量子效率分别为92.3%和48.1%,100℃强度保持率约89.6%。采用ZMGOF:0.1Cr^(3+)荧光粉封装制成的LED器件在100mA电流驱动下近红外光输出功率约34.5mW,能量转换效率约12.3%。

宽带近红外荧光材料InBO_(3)∶Cr^(3+)的发光性能及应用研究

近红外光谱技术在无损检测、生物成像和夜视等领域有着广阔的应用,开发一种小型化、快速响应的宽带近红外光源是其大规模应用的前提。基于近红外荧光粉的转换型发光二极管(NIR pc-LED)由于具有紧凑高效、成本低、寿命长等特点而备受关注。目前,开发高效稳定的宽带近红外发射材料成为该技术的关键。采用高温固相法合成了三方晶系的InBO_(3)∶Cr^(3+)荧光粉,在450nm蓝光的激发下,其实现了700~1100nm的宽带近红外发射。随着Cr^(3+)浓度的增加,荧光粉的发射带出现红移。得到的最佳掺杂浓度为2%Cr^(3+)(摩尔分数),其光学带隙为2.35eV,活化能ΔE为0.53eV。将荧光粉与蓝光芯片结合,构筑了具有宽带发射的NIR pc-LED器件。以该LED作为近红外光源,证实了其在生物医学成像和食品检测等领域的潜在应用前景。

Cr^(3+)掺杂对Mn_(3)O_(4)结构、形貌以及磁电性能的影响

为了探究Cr^(3+)掺杂对Mn_(3)O_(4)体系磁电效应的影响,采用传统固相法成功制备了Mn_(3)O_(4)及Mn_(1.8)Cr_(1.2)O_(4)的单相多晶样品。X射线衍射及精修结果表明,掺杂前后存在晶体结构的改变,由四方晶系转变为立方晶系,其空间群由I41/amd变为Fd3m。场发射扫描电镜结果显示,掺杂前样品的晶粒呈紧密的镶嵌结构,掺杂后样品呈离散的五面体及八面体形貌,且尺寸约是掺杂前的1/8。磁性研究结果表明,掺杂前、后样品Yafet-Kittel型亚铁磁相变温度由43 K提高到60 K,这源自Cr^(3+)掺杂使Mn^(3+)(Cr^(3+))/Mn^(2+)—O键长缩短,Mn^(3+)(Cr^(3+))—O—Mn^(3+)(Cr^(3+))键角增大,磁相互作用增强。此外,掺杂后矫顽力显著降低,这可根据离散的晶粒间作用力减小来理解。介电效应研究发现,掺杂前、后样品在磁相变点附近存在不随频率移动的介电异常峰,表明该体系存在与磁序相关的铁电极化,这源自体系的非线性磁结构。

大尺寸优质Cr^(3+)∶BeAl_(2)O_(4)晶体生长与性能研究

本文采用感应加热提拉法结合上称重自动控径技术,成功生长出大尺寸、高质量的翠绿宝石(Cr^(3+)∶BeAl_(2)O_(4))晶体。晶坯等径圆柱体尺寸达到ϕ70 mm×140 mm,晶坯质量超过2800 g。通过冷光源照射晶坯,发现晶坯中心区域ϕ10~15 mm存在气泡。采用5 mW绿光激光照射ϕ8 mm×130 mm的翠绿宝石晶体棒,晶体内部无散射颗粒。利用Zygo激光平面干涉仪对晶体棒进行测试,波前畸变为0.3λ@632.8 nm。用电感耦合等离子体原子发射光谱法测定了翠绿宝石晶体的铬离子掺杂浓度,并计算出轴向浓度梯度为0.5×10^(-4)~1.9×10^(-4)cm^(-1)(摩尔分数)。用Perkin Elmer Lambda-950紫外可见近红外分光光度计测试了不同掺杂浓度的翠绿宝石晶体在室温下的吸收光谱,并计算了吸收系数。这些研究结果为翠绿宝石晶体的应用提供了重要的基础数据。

近红外二区长波发射Na_(3)YSi_(3)O_(9):x Cr^(3+)硅酸盐及多格位占据光谱展宽

以Cr^(3+)为激活剂的荧光粉被认为是目前最有可能实现商业化的近红外材料.但目前这类荧光粉的发射波长一般位于小于850 nm的近红外一区,以Cr^(3+)为激活剂实现近红外二区发射仍然具有挑战.本文采用普适的固相法制备了一系列Na_(3)Y_(1–x)Si_(3)O_(9):x Cr^(3+)硅酸盐荧光粉,利用Na_(3)YSi_(3)O_(9)硅酸盐属性及结构中多种适于Cr^(3+)占据的八面体位点有效红移并展宽光谱.对样品的物相、晶体结构、微观形貌、光致发光、主发射峰衰减和热稳定性等进行了系统研究.结果显示,所制样品均为纯相,形貌不均匀略有团聚,尺寸在微米量级.Cr^(3+)在Na_(3)YSi_(3)O_(9)晶格中位于弱晶体场环境,八面体晶体场参数Dq和Racah参数B的比值Dq/B=2.29.在485 nm蓝光激发下Na3Y_(1–x)Si_(3)O_(9):x Cr^(3+)荧光粉最强发射峰位于984 nm处(NIR II区),长于大多数Cr^(3+)激活的荧光粉.且得益于Cr^(3+)在晶格中的多格位占据,发射光谱的半峰宽高达183 nm.Na3Y_(1–x)Si_(3)O_(9):x Cr^(3+)中最佳掺杂浓度为3%,猝灭机理为Cr^(3+)离子间的偶极-偶极作用.Na3Y_(1–x)Si_(3)O_(9):x Cr^(3+)主发射峰荧光衰减动力学分析表明室温荧光寿命约为37.95μs,且随着掺杂浓度增大及温度升高(至423 K)逐渐降低.

One-pot Synthesis of MoO_(3)/PI Composite with Enhanced Photocatalytic Performance for Oxidative Coupling of Amines to Imines

Organic-inorganic MoO_(3)/PI(MoPI)composites were prepared using a simple one-pot thermal copolymerization method.The resulting composites exhibited enhanced photocatalytic activity for the selective oxidation of benzylamine to N-benzylidene benzylamine(N-BDBA)in ambient air under simulated solar light irradiation compared to pristine MoO_(3) or polyimide(PI).In particular,the MoPI composite with a 0.3:1 molar ratio of Mo to melamine,referred to as MoPI-0.3,demonstrated the best performance in the photo-oxidation of benzylamine,achieving a benzylamine conversion of 95%with a N-BDBA selectivity exceeding 99%after 3 h irradiation.The enhanced photocatalytic activity of the MoPI-0.3 catalyst was attributed to the formation of a direct Z-scheme heterojunction between MoO_(3) and PI,facilitating more efficient separation of the photoinduced electrons and holes.Additionally,the MoPI-0.3 composite maintained considerably high activity over four consecutive cycles,highlighting its good stability and recyclability.Furthermore,the MoPI-0.3 composite could photo-oxidize benzylamine derivatives and heterocyclic amines to their corresponding imines,demonstrating the universal applicability of this composite catalyst.

Achieving structurally stable O3-type layered oxide cathodes through site-specific cation-anion co-substitution for sodium-ion batteries

O3-type layered oxides have garnered great attention as cathode materials for sodium-ion batteries because of their abundant reserves and high theoretical capacity.However,challenges persist in the form of uncontrollable phase transitions and intricate Na^(+)diffusion pathways during cycling,resulting in compromised structural stability and reduced capacity over cycles.This study introduces a special approach employing site-specific Ca/F co-substitution within the layered structure of O_(3)-NaNi_(0.5)Mn_(0.5)O_(2) to effectively address these issues.Herein,the strategically site-specific doping of Ca into Na sites and F into O sites not only expands the Na^(+)diffusion pathways but also orchestrates a mild phase transition by suppressing the Na^(+)/vacancy ordering and providing strong metal-oxygen bonding strength,respectively.The as-synthesized Na_(0.95)Ca_(0.05)Ni_(0.5)Mn_(0.5)O_(1.95)F_(0.05)(NNMO-CaF)exhibits a mild O3→O3+O'3→P3 phase transition with minimized interlayer distance variation,leading to enhanced structural integrity and stability over extended cycles.As a result,NNMO-CaF delivers a high specific capacity of 119.5 mA h g^(-1)at a current density of 120 mA g^(-1)with a capacity retention of 87.1%after 100 cycles.This study presents a promising strategy to mitigate the challenges posed by multiple phase transitions and augment Na^(+)diffusion kinetics,thus paving the way for high-performance layered cathode materials in sodium-ion batteries.

Exceptional Performance of 3D Additive Manufactured NiFe Phosphite Oxyhydroxide Hollow Tubular Lattice Plastic Electrode for Large-Current-Density Water Oxidization

In this article,we report a 3D NiFe phosphite oxyhydroxide plastic electrode using high-resolution digital light processing(DLP)3D-printing technology via induced chemical deposition method.The as-prepared 3D plastic electrode exhibits no template requirement,freedom design,low-cost,robust,anticorrosion,lightweight,and micro-nano porous characteristics.It can be drawn to the conclusion that highly oriented open-porous 3D geometry structure will be beneficial for improving surface catalytic active area,wetting performance,and reaction–diffusion dynamics of plastic electrodes for oxygen evolution reaction(OER)catalysis process.Density functional theory(DFT)calculation interprets the origin of high activity of NiFe(PO_(3))O(OH)and demonstrates that the implantation of the–PO_(3)can effectively bind the 3d orbital of Ni in NiFe(PO_(3))O(OH),lead to the weak adsorption of intermediate,make electron more active to improve the conductivity,thereby lowing the transform free energy of*O to*OOH.The water oxidization performance of as-prepared 3D NiFe(PO_(3))O(OH)hollow tubular(HT)lattice plastic electrode has almost reached the state-of-the-art level compared with the as-reported large-current-density catalysts or 3D additive manufactured plastic/metal-based electrodes,especially for high current OER electrodes.This work breaks through the bottleneck that plagues the performance improvement of low-cost high-current electrodes.

3D printing of poly(ethyleneimine)-functionalized Mg-Al mixed metal oxide monoliths for direct air capture of CO_(2)

Direct air capture(DAC)of CO_(2)plays an indispensable role in achieving carbon-neutral goals as one of the key negative emission technologies.Since large air flows are required to capture the ultradilute CO_(2)from the air,lab-synthesized adsorbents in powder form may cause unacceptable gas pressure drops and poor heat and mass transfer efficiencies.A structured adsorbent is essential for the implementation of gas-solid contactors for cost-and energy-efficient DAC systems.In this study,efficient adsorbent poly(ethyleneimine)(PEI)-functionalized Mg-Al-CO_(3)layered double hydroxide(LDH)-derived mixed metal oxides(MMOs)are three-dimensional(3D)printed into monoliths for the first time with more than 90%adsorbent loadings.The printing process has been optimized by initially printing the LDH powder into monoliths followed by calcination into MMO monoliths.This structure exhibits a 32.7%higher specific surface area and a 46.1%higher pore volume,as compared to the direct printing of the MMO powder into a monolith.After impregnation of PEI,the monolith demonstrates a large adsorption capacity(1.82 mmol/g)and fast kinetics(0.7 mmol/g/h)using a CO_(2)feed gas at 400 ppm at 25℃,one of the highest values among the shaped DAC adsorbents.Smearing of the amino-polymers during the post-printing process affects the diffusion of CO_(2),resulting in slower adsorption kinetics of pre-impregnation monoliths compared to post-impregnation monoliths.The optimal PEI/MeOH ratio for the post-impregnation solution prevents pores clogging that would affect both adsorption capacity and kinetics.

Cr^(3+)掺杂Y_(3)Al_(5)O_(12)-Al_(2)O_(3)的光致发光和温度传感特性研究

为了开发具有高发光效率和高测温灵敏度的光学温度传感材料,采用高温固相法合成了一系列Cr^(3+)掺杂Y_(3)Al_(5)O_(12)-xAl_(2)O_(3)(x=0,0.5,1.25,2,2.75,3.5)固熔体。利用X射线衍射、扫描电子显微镜、傅里叶红外光谱、稳态激发和发射光谱表征,详细研究了Y_(3)Al_(5)O_(12)中Al_(2)O_(3)的掺杂浓度对其结构和发光性能的影响。研究表明,提高Al_(2)O_(3)掺杂量可以增加固熔体中的八面体配位,同时削弱了晶体场强度,有利于Cr^(3+)的发光。在303~773 K温度范围内,利用该材料中Cr^(3+)荧光寿命以及热耦合能级荧光强度比的温度依赖特性进行测温研究,两种方法的相对测温灵敏度分别在500 K时达到最大值0.802%K^(-1),在303 K时达到最大值0.977%K^(-1)。除此之外,本文首次提出利用激光强度与荧光强度之比作为测温参数的比率型测温方法,在773 K时取得最大相对测温灵敏度为1.036%K^(-1)。上述研究结果表明,Cr^(3+)掺杂Y_(3)Al_(5)O_(12)-xAl_(2)O_(3)固熔体材料具有良好的光学温度传感特性,三种不同模式的测温方法为该材料在发光测温领域的应用提供了广阔的前景。

Yb^(3+)/Nd^(3+)掺杂对Sr_(9)Ga(PO_(4))_(7)∶Cr^(3+)发光性能的影响

近红外荧光粉由于其独特的物理特性和广阔的应用前景吸引了人们极大的研究兴趣。本文通过高温固相反应法合成Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+)近红外荧光粉,使用460 nm蓝光激发样品的发射波长位于833 nm,半峰宽为117 nm。随后引入稀土离子合成Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),Yb^(3+)和Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),Nd^(3+)近红外荧光粉。相比Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),460 nm蓝光激发的Sr_(9)Ga(PO_(4))_(7)∶0.8Cr^(3+),Yb^(3+)同时出现Cr^(3+)和Yb^(3+)特征发射峰,经过光谱分析和荧光寿命变化证明Cr^(3+)-Yb^(3+)存在能量传递通道,最高使Cr^(3+)-Yb^(3+)能量传递效率达80.2%,得益于Yb^(3+)卓越的热稳定性促使整体荧光光谱热稳定性提高约3.7倍。设计合成的Sr_(9)Ga(PO_(4))_7∶0.8Cr^(3+),Nd^(3+)样品调制出833,876,1 060 nm的多峰发射,显著拓宽了近红外光谱范围。最终,讨论了荧光粉在温度传感和无损检测领域的应用,证明该系列荧光粉具有广阔的应用前景。

Cr^(3+)掺杂Ca_(4)HfGe_(3)O_(12)宽带近红外荧光粉的发光特性及应用

近红外荧光粉在生物活体成像领域展现出重要的应用前景。但活体成像用近红外荧光粉存在种类匮乏、耐温性差等瓶颈问题。采用固相法合成了宽带近红外Ca_(4)HfGe_(3)O_(12):xCr^(3+)(0≤x≤0.09)荧光粉。X射线衍射和能谱分析的结果表明Cr^(3+)离子成功进入Ca_(4)HfGe_(3)O_(12)晶格。在469 nm蓝光激发下,Ca_(4)HfGe_(3)O_(12):xCr^(3+)荧光粉发射出690~1200 nm的宽带近红外光,峰值波长为825 nm(4T2-4A2),半高宽达到141 nm,Cr^(3+)掺杂最佳浓度为0.03。依据激发光谱峰形和寿命衰减行为,证实Cr^(3+)仅占据基质中一种阳离子格位。Ca_(4)HfGe_(3)O_(12):0.03Cr^(3+)荧光粉的荧光量子效率为33.63%,该荧光粉发射光谱在400 K下的积分面积为室温下的60.5%,表明该样品具有优良的热稳定性。采用自制近红外荧光粉转换器件照射人手掌和滤波片遮挡的水果,观察到清晰地静脉血管和遮挡水果的轮廓。