Insights on advanced g‐C_(3)N_(4)in energy storage:Applications,challenges,and future

Graphitic carbon nitride(g‐C_(3)N_(4))is a highly recognized two‐dimensional semiconductor material known for its exceptional chemical and physical stability,environmental friendliness,and pollution‐free advantages.These remarkable properties have sparked extensive research in the field of energy storage.This review paper presents the latest advances in the utilization of g‐C_(3)N_(4)in various energy storage technologies,including lithium‐ion batteries,lithium‐sulfur batteries,sodium‐ion batteries,potassium‐ion batteries,and supercapacitors.One of the key strengths of g‐C_(3)N_(4)lies in its simple preparation process along with the ease of optimizing its material structure.It possesses abundant amino and Lewis basic groups,as well as a high density of nitrogen,enabling efficient charge transfer and electrolyte solution penetration.Moreover,the graphite‐like layered structure and the presence of largeπbonds in g‐C_(3)N_(4)contribute to its versatility in preparing multifunctional materials with different dimensions,element and group doping,and conjugated systems.These characteristics open up possibilities for expanding its application in energy storage devices.This article comprehensively reviews the research progress on g‐C_(3)N_(4)in energy storage and highlights its potential for future applications in this field.By exploring the advantages and unique features of g‐C_(3)N_(4),this paper provides valuable insights into harnessing the full potential of this material for energy storage applications.

In situ luminescence measurements of GaN/Al_(2)O_(3) film under different energy proton irradiations

Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the material.The energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were observed.The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN film.Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy.Luminescence measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions.The evolution of defects at different layers with ion fluence can be obtained.

高热稳定CaGdAlO_(4)∶Er^(3+)/Yb^(3+)荧光粉的上转换发光及其温度传感性能

获得具有良好热稳定性和发光性能的非接触式光学温度传感材料是目前的研究热点之一,本工作通过高温固相法制备了Er^(3+)/Yb^(3+)共掺CaGdAlO_(4)∶Er_(x),Yb_(0.10)(x=0.006、0.008、0.010、0.012、0.014)荧光粉,尺寸大小分布在0.6~4.2μm。在980 nm激光激发下,该荧光粉在500~700 nm发射谱由两个发射带组成,528和550 nm处两个较强的绿光发射带,归属于Er^(3+)的^(2)H_(11/2)→^(4)I_(15/2)、^(4)S_(3/2)→^(4)I_(15/2)能级跃迁,663 nm处较弱的红光发射带,归属于Er^(3+)的^(4)F_(9/2)→^(4)I_(15/2)能级跃迁。上转换发光强度最大组分为CaGdAlO_(4)∶Er_(0.010),Yb_(0.10)。300~573 K变温发射谱表明,基于荧光强度比FIR_(528/550)参数,温度传感绝对灵敏度S_(A)从44.4×10^(-4) K^(-1)(@300 K)先增大到52.0×10^(-4) K^(-1)(@445 K)随后减小到49.0×10^(-4) K^(-1)(@573 K)。相对灵敏度S_(R)则从0.95×10^(-2) K^(-1)(@300 K)单调减小到0.27×10^(-2) K^(-1)(@573 K)。冷热循环实验表明该材料的热重复性优于98%。结果表明,CaGdAlO_(4)∶Er_(0.010),Yb_(0.10)荧光粉在光学温度传感领域具有潜在的应用前景。

Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体的光谱分析及中红外发射增强

采用非化学计量配比的提拉法成功生长出Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体、Er^(3+)/Yb^(3+):SrLaGaO_(4)和Er^(3+):SrLaGaO_(4)晶体并进行了详细的光谱分析,同时对纯的SrLaGaO_(4)晶体进行了热学性能分析。与Er^(3+):SrLaGaO_(4)晶体相比,Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体不仅展示了更好的吸收特性,而且还表现出较弱的近红外发射,以及优异的中红外发射;Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中2.7μm铒激光下能级4I13/2的荧光寿命显著减少,而上能级4I11/2的寿命略微下降,成功抑制了自终止效应。此外,本工作还研究了Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中Yb^(3+)的敏化作用和Pr^(3+)离子的去激活作用以及能量传递机制。总之,引入Yb^(3+)和Pr^(3+)有利于在Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中实现增强的2.7μm发射,这使其成为中红外激光有前途的候选材料。

3μm波段Er^(3+)∶ZBLAN光纤激光器研究进展及展望

3µm激光处于分子指纹区,在医疗外科、气体检测、军事应用等领域都有重要的应用价值。Er^(3+)∶ZBLAN光纤激光器具有效率高、可集成的优点,是3µm激光的主要输出方式。本文从铒离子跃迁产生3µm激光出发,围绕Er^(3+)∶ZBLAN光纤激光器,介绍了3µm激光产生的结构原理及能级系统,总结了实现该波段高功率连续输出和脉冲输出的技术方案和研究进展,重点介绍了基于不同材料可饱和吸收体的调Q和锁模激光器实验研究,并对目前实现3µm波段高功率输出需要解决的问题进行了分析,最后对Er^(3+)∶ZBLAN激光器的发展方向进行了展望。

棒状结构NaGdF_(4):Yb^(3+),Er^(3+)上转换发光性能的研究

以乙二胺四乙酸二钠(EDTD-2Na)为螯合剂,采用水热法合成了棒状结构的NaGdF_(4):Yb^(3+),Er^(3+)纳米粉末。分别借助X射线衍射(XRD)、荧光光谱仪(PL)和扫描显微镜(SEM)对其晶体结构、发光强度和表面形貌进行分析和表征。探究了稀土前驱体、水热温度和水热时间的实验条件对NaGdF_(4):Yb^(3+),Er^(3+)纳米粉末上转换发光强度的影响;研究了氟源和钠源对NaGdF_(4):Yb^(3+),Er^(3+)晶体形貌和上转换发光强度的改善;同时,采用煅烧处理的方法,进一步探究样品的形貌和发光强度收到的影响。实验结果表明NH4F与NaOH作为氟源和钠源及200℃煅烧1 h得到的棒状结构NaGdF_(4):Yb^(3+),Er^(3+)的发光强度最好,色坐标(CIE)绿色发光强度从84%提升到94.88%。

KYb_(2)F_(7):2%Er^(3+)荧光材料的制备、发光机制及温度传感性能

采用简易水热法制备了正交相KYb_(2)F_(7):2%Er^(3+)上转换荧光材料。利用X射线衍射仪和扫描电子显微镜确定所合成样品均为六角状纯相材料。在980 nm激光激发下,KYb_(2)F_(7):2%Er^(3+)荧光材料展现了位于527 nm和545 nm的两个绿光发射峰和位于655 nm处的红光发射峰,且上转换发光出现少见的以红光为主的现象。变温光谱结果表明,545 nm和655 nm处的发射强度随温度升高均呈现热猝灭。基于热耦合测温原理,对Er^(3+)的^(2)H_(11/2)→^(4)I_(11/2)和^(4)S_(3/2)→^(4)I1_(1/2)两个热耦合能级进行温度传感性能研究,计算了发光温度计的发光强度比(LIR)、绝对灵敏度(S_(a))、相对灵敏度(S_(r))、温度不确定度(δ_T)和可重复度(R),其中最大相对灵敏度在313 K时为0.99%·K^(-1),最小温度不确定度在313 K时为0.73 K,可重复度超过99%,确保了该温度计的可靠性。实验结果表明KYb_(2)F_(7):2%Er^(3+)荧光材料在温度传感方面具有潜在应用价值。

不同激发波长下NaLaF_(4):Er^(3+)/Yb^(3+)的上转换光谱调控研究

为探究不同激发波长(980 nm、1 550 nm)对NaLaF_(4):Er^(3+)/Yb^(3+)上转换发光材料光谱调控的规律和机理,采用水热-固相两步反应法合成一系列不同Er^(3+)/Yb^(3+)掺杂浓度的NaLaF_(4)荧光粉。利用X射线衍射仪(XRD)、荧光分光光度计对材料进行测试,分析其发光性能与机理。结果表明,样品在980 nm激发下呈绿色发光,上转换发光强度随Er^(3+)/Yb^(3+)掺杂浓度增加而呈现先增后减的规律,该发光过程为双光子过程;而在1 550 nm激发下呈红色发光,上转换发光强度随Er^(3+)掺杂浓度增加而呈增强趋势,但随Yb^(3+)浓度增加而降低,发光过程为三光子过程。因此,通过调节激发光波长,在同组分NaLaF_(4):Er^(3+)/Yb^(3+)荧光粉中实现颜色可控的绿、红色发光,对设计新型光谱调控手段和探索新的发光材料具有一定的理论指导意义。

溶剂热法制备NaScF_(4):Yb^(3+)/Er^(3+)及其发光性能的研究

利用溶剂热法在油酸(OA),正辛醇(OC)及乙二醇(EG)三溶剂中成功制备出NaScF_(4):Yb^(3+)/Er^(3+)纳米颗粒。调节三种溶剂的不同比例观察对样品晶相、结构、尺寸及发光强度的影响。此外,我们使用了X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、荧光光谱仪对样品进行了表征。通过XRD证明在OA、OC、EG分别为16mL,12mL、4mL时成功合成出了纯相的NaScF_(4):Yb^(3+)/Er^(3+)纳米颗粒。SEM图进一步证明样品形貌均匀,分散性较好,粒径较小,颗粒尺寸为37.62±9.36nm。此外,样品的荧光光谱表明样品在980nm激光激发下能发射出红色荧光。因此,该方法下制备的NaScF_(4):Yb^(3+)/Er^(3+)尺寸较小,形貌较均匀,拥有强的红色发射且该材料有望用于生物成像、信息储存,防伪等领域。

新型Al_2O_(3)-CaO-ZnO玻璃制备与Er^(3+)∶2.7 μm中红外发光性能

3 μm波段的中红外光纤激光器在生物医疗、环境监测和军事等领域具有重要的应用前景,在国内外受到了广泛的关注和研究。低声子能量、高效稳定的中红外玻璃作为光纤激光器的核心工作介质,是实现3 μm波段中红外激光的重要基础。本文采用熔融-淬冷法制备了掺Er^(3+)新型Al_2O_(3)-CaO-ZnO玻璃,通过热分析、拉曼光谱、透射光谱以及光致发光光谱等对玻璃的热力学、结构、透过波长范围和中红外发光性能进行了表征。结果表明,Al_(2)O_(3)-CaO-ZnO玻璃具有较高的玻璃化转变温度(~750℃)、较低的声子能量(~780 cm^(-1))以及较宽的透过波长范围(0.5~5 μm);在980 nm激光激发下,在掺Er^(3+)玻璃中观察到了明显的2.7 μm(Er^(3+)∶^(4)I_(11/2)→^(4)I_(13/2))波段荧光发射。研究结果表明Al_(2)O_(3)-CaO-ZnO体系玻璃是一种优良的中红外激光基质材料。

动态缺陷导致Na_(3)Sc_(2)(PO_(4))_(3):Yb^(3+),Er^(3+)材料上转换和下转移发光不同热猝灭行为研究

掺Eu^(2+)的离子导体Na_(3)Sc_(2)(PO_(4))_(3)具有优异的抗热猝灭性能,是一种很有前景的大功率照明用发光材料。然而,其负热猝灭机理仍有待深入研究。本文以Yb^(3+)/Er^(3+)的f-f跃迁上转换和下转移窄带发射而非更易受干扰的Eu^(2+)d-f跃迁发射为研究对象,旨在获得更清晰的机理。结果表明,热致缺陷/离子的动态迁移能促进高温下辐射跃迁和抑制非辐射跃迁,导致上转换发光具有显著的负热猝灭,下转移发光热猝灭较小。其中,布居速率较慢的上转换过程更容易受到时间尺度与之相当的Na^(+)/空位迁移过程的影响。本研究可为理解发光材料热猝灭机制提供另一种视角。

Solid-state NMR study on sodium intercalation at low voltage window for Na_(3)V_(2)(PO_(4))_(3) as an anode

In-situ XRD,^(31)P NMR and ^(23)Na NMR were used to analyze the interaction behavior of Na_(3)V_(2)(PO_(4))_(3) at low voltage,and then a new intercalation model was proposed.During the transition from Na_(3)V_(2)(PO_(4))_(3) to Na_(4)V_(2)(PO_(4))_(3),Na ions insert into M1,M2 and M3 sites simultaneously.Afterwards,during the transition of Na_(4)V_(2)(PO_(4))_(3)to Na_(5)V_(2)(PO_(4))_(3),Na ions mainly insert into M3 site.

Y_(2)O_(3):Yb^(3+),Er^(3+)上转化荧光纳米粒子在潜指纹显现中的应用

文章通过高温煅烧方法制备出Y_(2)O_(3):Yb^(3+),Er^(3+)纳米粒子,通过XRD、TEM和元素面扫描对其特性进行研究。通过该方法成功制备出Y_(2)O_(3):Yb^(3+),Er^(3+)纳米粒子,该纳米粒子具有较好的分散性,尺寸约为100 nm。在980 nm近红外光的激发下,产生绿色和红色两个发光带。Y_(2)O_(3):Yb^(3+),Er^(3+)在980 nm近红外光的激发下,可以有效地显现红色纸盒和绿色塑料卡片等带有颜色干扰的非渗透性客体表面的潜指纹,由于激发波长为近红外光,可以完全避免背景荧光的干扰,最大程度上显现指纹的一级和二级结构特征。此外,在与商品红色荧光粉末的比较研究中发现,在有荧光特性的渗透性客体表面的潜指纹显现中,Y_(2)O_(3):Yb^(3+),Er^(3+)纳米粒子具有优势,呈现出更加清晰的指纹轮廓和纹线,可以有效消除背景花纹的干扰,具有较高的灵敏度和选择性。

Interfacial built-in electric field and crosslinking pathways enabling WS_(2)/Ti_(3)C_(2)T_(x) heterojunction with robust sodium storage at low temperature

Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

Effects of anti-CD4 antibody treatment on calcium ions influx in peanut-sensitized C3H/HeJ mice

The precise mechanism underlying the effects of anti-CD4 antibody and calcium ions(Ca^(2+)) in peanut allergy remains unknown.C3 H/HeJ mice sensitized with peanut protein extract(PPE)were injected with anti-CD4 antibodies for 4 weeks.Stimulation with PPE increased the specific immunoglobulin E(IgE),cytokine,histamine,and mMcp-1 levels,upregulated decorin(Dcn)expression,induced Ca^(2+) inflow in the spleen,and augmented the expression of the transcription factors GATA-3 and Foxp3,which resulted in Th2 and Treg cell activation.Notably,the Ca^(2+) levels were positively correlated with the histamine,interleukin(IL)-4,IL-5,and IL-13 levels,and negatively correlated with IL-10 levels.However,administration of anti-CD4 antibodies markedly alleviated allergic symptoms,activated T cells,and reduced Ca^(2+) inflow,cytokine,histamine,mMcp-1,and the IgHG3,CXCLI2,MMP2 and FABP4 gene.Our results indicated that anti-CD4 antibodies can ameliorate PPE-induced allergy,which is probably related to the suppression of Ca^(2+) inflow,and inhibiting histamine,cytokine and IgHG3,CXCL12,MMP2,and FABP4,thus exerting a protective effect against PPEsensitized food allergy.

Green and red up-conversion emissions and thermometric application of Er^(3+) -doped silicate glass

The green and red up-conversion emissions centred at about 534, 549 and 663 nm of wavelength, corresponding respectively to the ^2H11/2 → ^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 → ^4I15/2 transitions of Er^3＋ ions, have been observed for the Er^3＋-doped silicate glass excited by a 978 nm semiconductor laser beam. Excitation power dependent behaviour of the up-conversion emission intensity indicates that a two-photon absorption up-conversion process is responsible for the green and red up-conversion emissions. The temperature dependence of the green up-conversion emissions is also studied in a temperature range of 296-673 K, which shows that Er^3＋-doped silicate glass can be used as a sensor in high-temperature measurement.

Optical-transition Probability of Tm^(3+) Ions in Tm^(3+)/Er^(3+):YVO_4 Crystal

The polarized absorption spectra of Tm3+/Er3+:YVO4 crystal were measured at room temperature. Based on the Judd-Ofelt theory, the spectral parameters were obtained: the intensity parameters Wl of Tm3+ in Tm/Er:YVO4 crystal: W2 = 10.69×10-20, W4 = 0.604×10-20, W6 = 2.05×10-20 cm2 for the (100) face and W2 = 10.43×10-20, W4 = 0.13×10-20, W6 = 1.83×10-20 cm2 for the (001) face. Based on these values, the oscillator strength, radioactive lifetime and fluorescence branch ratio were calculated for Tm3+ in Tm/Er:YVO4 crystal.

Upconversion of Er^(3+) Ions in LiKGdF_5:Er^(3+),Dy^(3+) Single Crystal Produced by Infrared and Green Laser

The upconversion fluorescence of Er^3＋ ions in LiKGdF5 ： Er^3＋, Dy^3＋ single crystal was studied under 785, 514.5, and 980 nm laser excitation. With the laser excitation set at 785 nm, strong green （centered at 543 nm） upconversion emissions, as well as weak red （651 nm）, violet （406 nm）, and blue （470 nm） upconversion emissions were obtained. With 514.5 nm laser excitation, violet （406 nm） and blue （470 nm） upconversion emissions were observed. Under 980 nm laser excitation, strong green （543 nm） and weak red （651） emissions were also obtained. The laser power dependence of the upconverted emissions was investigated to understand the upconversion mechanism. The excited state absorption （ESA） and the energy transfer （ET） processes were discussed as the possible mechanisms for all upconversion emissions.

Covalent bonding and J–J mixing effects on the EPR parameters of Er^(3+) ions in GaN crystal

The EPR parameters of trivalent Er（3＋） ions doped in hexagonal Ga N crystal have been studied by diagonalizing the 364×364 complete energy matrices. The results indicate that the resonance ground states may be derived from the Kramers doublet Γ6. The EPR g-factors may be ascribed to the stronger covalent bonding and nephelauxetic effects compared with other rare-earth doped complexes, as a result of the mismatch of ionic radii of the impurity Er（3＋）ion and the replaced Ga（3＋） ion apart from the intrinsic covalency of host Ga N. Furthermore, the J–J mixing effects on the EPR parameters from the high-lying manifolds have been evaluated. It is found that the dominant J–J mixing contribution is from the manifold 2K（15/2）, which accounts for about 2.5%. The next important J–J contribution arises from the crystal–field mixture between the ground state 4I（15/2） and the first excited state4I（13/2）, and is usually less than 0.2%. The contributions from the rest states may be ignored.