Construction of nitrogen and phosphorus co-doped graphene quantum dots/Bi5O7I composites for accelerated charge separation and enhanced photocatalytic degradation performance

Nitrogen and phosphorus co-doped graphene quantum dot-modified Bi5O7 I(NPG/Bi5O7 I)nanorods were fabricated via a simple solvothermal method.The morphology,structure,and optical properties of the as-prepared samples were investigated by X-ray diffraction,scanning electron microscopy,high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy(XPS),and diffused reflectance spectroscopy.The photocatalytic performance was estimated by degrading the broad-spectrum antibiotics tetracycline and enrofloxacin under visible light irradiation.The photodegradation activity of Bi5O7 I improved after its surface was modified with NPGs,which was attributed to an increase in the photogenerated charge transport rate and a decrease in the electron-hole pair recombination efficiency.From the electron spin resonance spectra,XPS valence band data,and free radical trapping experiment results,the main active substances involved in the photocatalytic degradation process were determined to be photogenerated holes and superoxide radicals.A possible photocatalytic degradation mechanism for NPG/Bi5O7 I nanorods was proposed.

Construction of N,O co-doped carbon anchored with Co nanoparticles as efficient catalyst for furfural hydrodeoxygenation in ethanol

Hydrodeoxygenation of furfural(FF)into 2-methylfuran(MF)is a significant biomass utilization route.However,designing efficient and stable non-noble metal catalyst is still a huge challenge.Herein,we reported the N,O co-doped carbon anchored with Co nanoparticles(Co-SFB)synthesized by employing the organic ligands with the target heteroatoms.Raman,electron paramagnetic resonance(EPR),electrochemical impedance spectroscopy(EIS),and X-ray photoelectron spectroscopy(XPS)characterizations showed that the co-doping of N and O heteroatoms in the carbon support endows Co-SFB with enriched lone pair electrons,fast electron transfer ability,and strong metal-support interaction.These electronic properties resulted in strong FF adsorption as well as lower apparent reaction activation energy.At last,the obtained N,O co-doped Co/C catalyst showed excellent catalytic activity(nearly 100 mol%FF conversion and 94.6 mol%MF yield)and stability for in-situ dehydrogenation of FF into MF.This N,O co-doping strategy for the synthesis of highly efficient catalytic materials with controllable electronic state will provide an excellent opportunity to better understand the structure-function relationship.

Preparation and Photocatalytic Activity of Ce, H3PW12O40 co-doped TiO2 Hollow Fibers

A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.

Biomass Template Derived Boron/Oxygen Co-Doped Carbon Particles as Advanced Anodes for Potassium-Ion Batteries

Among various anode candidates for potassium-ion batteries,carbonaceous materials have attracted significant attention due to their overwhelming advantages including cost-effectiveness and environmental benignity.However,the inferior specific capacity and the sluggish reaction kinetics hinder the further development in this realm.Herein,we report biomass templated synthesis of boron/oxygen heteroatom co-doped carbon particles(BO-CPs)via direct plasma-enhanced chemical vapor deposition.With the combined advantages of abundant active sites,large accessible surface area,and functional groups,BO-CP anode exhibits high reversible specific capacity(426.5 mAh g^(-1)at 0.1 A g^(-1))and excellent rate performance(166.5 mAh g^(-1)at 5 A g^(-1)).The K-ion storage mechanism is probed by operando Raman spectroscopy,ex situ X-ray photoelectron spectroscopy/electrochemical impedance spectroscopy,galvanostatic intermittent titration technique measurements,and theoretical simulations.The synergistic effect of boron and oxygen co-doping greatly facilitates the performance of carbon-based anode,wherein boron dopant improves the conductivity of carbon framework and the oxygen dopant affords ample active sites and thus harvests additional specific capacity.This work is anticipated to propel the development of high-performance anode materials for emerging energy storage devices.

Spectroscopy and Energy Transfer in Yb^(3+) and Tm^(3+) Co-doped Gd_3Ga_5O_(12) Crystal

Yb3＋/Tm3＋ co-doped Gd3Ga5O12 single crystal with a dimension of Φ30mm×20mm was grown successfully by Czochralski method.The absorption spectrum was recorded at room temperature and used to calculate the absorption cross-section.Based on the Judd-Ofelt（J-O） theory,we obtained the three intensity parameters and spectral parameters of this crystal,such as the line strengths,oscillator strengths,radiative probabilities and radiative lifetimes as well as the fluorescent branching ratios.Room temperature fluorescence spectra and luminescence decay curves were recorded.The energy transfer between Yb3＋-Tm3＋ was observed and the mechanism was discussed.The stimulated emission cross-section of the 3F4→3H6 transition was calculated by the Füchtbauer-Ladenburg（F-L） equation.The potential laser gains for this transition were also investigated.This crystal is promising as a tunable infrared laser crystal at 2.0 μm.

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.

Multiple-dimensioned defect engineering for graphite felt electrode of vanadium redox flow battery

The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledimensioned defect,including nano-scale etching and atomic-scale N,O codoping,was used to modify GF by the molten salt system.NH_(4)Cl and KClO_(3) were added simultaneously to the system to obtain porous N/O co-doped electrode(GF/ON),where KClO_(3) was used to ultra-homogeneously etch,and O-functionalize electrode,and NH4Cl was used as N dopant,respectively.GF/ON presents better electrochemical catalysis for VO_(2)+/VO_(2)+ and V3+/V2+ reactions than only O-functionalized electrodes(GF/O)and GF.The enhanced electrochemical properties are attributed to an increase in active sites,surface area,and wettability,as well as the synergistic effect of N and O,which is also supported by the density functional theory calculations.Further,the cell using GF/ON shows higher discharge capacity,energy efficiency,and stability for cycling performance than the pristine cell at 140 mA cm^(−2) for 200 cycles.Moreover,the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm^(−2).Such an ultra-homogeneous etching with N and O co-doping through“boiling”molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.

Double-Doped Carbon-Based Electrodes with Nitrogen and Oxygen to Boost the Areal Capacity of Zinc-Bromine Flow Batteries

Ensuring a stable power output from renewable energy sources,such as wind and solar energy,depends on the development of large-scale and long-duration energy storage devices.Zinc–bromine fl ow batteries(ZBFBs)have emerged as cost-eff ective and high-energy-density solutions,replacing expensive all-vanadium fl ow batteries.However,uneven Zn deposition during charging results in the formation of problematic Zn dendrites,leading to mass transport polarization and self-discharge.Stable Zn plating and stripping are essential for the successful operation of high-areal-capacity ZBFBs.In this study,we successfully synthesized nitrogen and oxygen co-doped functional carbon felt(NOCF4)electrode through the oxidative polymerization of dopamine,followed by calcination under ambient conditions.The NOCF4 electrode eff ectively facilitates effi cient“shuttle deposition”of Zn during charging,signifi cantly enhancing the areal capacity of the electrode.Remarkably,ZBFBs utilizing NOCF4 as the anode material exhibited stable cycling performance for 40 cycles(approximately 240 h)at an areal capacity of 60 mA h/cm^(2).Even at a high areal capacity of 130 mA h/cm^(2),an impressive energy effi ciency of 76.98%was achieved.These fi ndings provide a promising pathway for the development of high-areal-capacity ZBFBs for advanced energy storage systems.

V_(2)O_(3)/VO_(2)@S/N-C nanofibers with excellent cycling stability and superior rate capability in aqueous zinc ion batteries

The development of aqueous zinc-ion batteries (AZIBs) marks a significant advancement in the field of sustainable and environmentally friendly energy storage.To address the challenges faced by singlephase vanadium-based oxides,such as poor conductivity and dissolution in electrolytes,this study introduces vacuum S/N doping to fabricate V_(2)O_(3)/VO_(2)@S/N-C nanofibers,improving the cycling stability and enhancing the capacity.The V_(2)O_(3)/VO_(2)@S/N-C electrode exhibits exceptional cyclic stability,retaining a capacity of 133.3 m A h g^(-1)after 30,000 cycles at a high current density of 100 A g^(-1)and a capacity retention of 81.8%after 150,000 cycles at 200 A g^(-1).Characterizations using ex-situ X-ray diffraction and ex-situ X-ray photoelectron spectroscopy reveal co-intercalation of H^(+)and Zn^(2+)in the V_(2)O_(3)/VO_(2)@S/N-C electrode.Due to the presence of S_(2)^(2-),more phases changed to V_(10)O_(24).12H_(2)O,making the V_(2)O_(3)/VO_(2)@S/N-C electrode better reversible.By elucidating the zinc storage mechanism and demonstrating the stable performance of the doped electrode,this work contributes valuable insights into the optimization of the electrode materials for future energy storage solutions.

La掺杂氧空位的α-Bi_(2)O_(3)电子结构和光学性质的第一性原理研究

基于第一性原理的方法研究了本征α-Bi_(2)O_(3)、La掺杂、氧空位掺杂和共掺杂体系的电子结构与光学性质,以期获得性能比较优异的α-Bi_(2)O_(3)光催化材料。研究结果表明:掺杂后,体系结构变形较小,其中氧空位(V_(O))掺杂和La-V_(O)共掺杂体系的禁带宽度价带和导带同时下移且在禁带中引入杂质能级,说明掺杂可以减小电子从价带激发到导带所需能量,有利于电子的跃迁。特别是相对于氧空位单掺杂,La-V_(O)共掺杂使杂质能级向导带底靠近,这个倾向可能使该复合缺陷成为光生电子捕获中心的概率大于成为光生电子-空穴对复合中心的概率;同时,La-V_(O)共掺杂导致导带底附近的能带弯曲的曲率增大即色散关系增强,从而降低了电子的有效质量,加速电子的运动,因此,La-V_(O)共掺杂能大幅改善光生电子-空穴对的有效分离。另一方面La-V_(O)共掺杂在显著扩展可见光吸收范围的同时,还极大地增强了可见光吸收强度。因此,La-V_(O)共掺杂有效改善了α-Bi_(2)O_(3)的光催化活性。本研究为利用稀土离子掺杂改善其他光催化材料的性能提供了一个新的思路。

N,O Co-Doping Enhanced Adsorption of Chloramphenicol for Highly Efficient and Robust Electrocatalytic Hydrodechlorination

Electrocatalysis technology can effectively promote the hydrodechlorination of chloramphenicol(CAP)to reduce the bio-toxicity.However,there are still some challenges such as low degradation rate and poor stability.Here,we prepared porous N,O co-doped carbon supported Pd nanoparticles composites(Pd NPs/NO-C)for electrocatalytic degradation of CAP.The doping of N and O not only effectively enhanced the interaction between substrate and CAP,promoting the mass transfer process,but also enhanced the anchoring effect on Pd nanoparticles,avoiding the occurrence of aggregation.The prepared composites achieved removal efficiency of CAP over 99%within 1 h,and the rate constant was as high as 6.72 h^(–1),outperforming previous reported electrocatalysts.Additionally,Pd NPs/NO-C composites showed a wide range of pH tolerance,excellent ion interference resistance and long-term stability.Our work unravels the importance of mass transfer processes in solution to electrocatalytic hydrodechlorination and provides new research ideas for catalysts design.

Synthesis and characterization of LiNi_(0.95-x)Co_xAl_(0.05)O_2 for lithium-ion batteries

Samples of LiNi0.95-xCoxAl0.05O2 （x = 0.10 and 0.15） and LiNiO2, synthesized by the solid-state reaction at 725℃ for 24 h from LiOH-H2O, Ni2O3, Co2O3, and AI（OH）3 under an oxygen stream, were characterized by TG-DTA, XRD, SEM, and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially, 5 at.% A1 and 10 at.% Co） definitely had a large beneficial effect in increasing the capacity （186.2 mA.h/g of the first discharge capacity for LiNio.s.42OoaoAlo.0502） and cycling behavior （180.1 mA-h/g after 10 cycles for LiNio.85CooaoAlo.osO2） compared with 180.7 mA.h/g of the first discharge capacity and 157.7 mA.h/g of the tenth discharge capacity for LiNiO2, respectively. Differen- tial capacity versus voltage curves showed that the co-doped LiNio.95_xCoxmlo.osO2 had less intensity of the phase transitions than the pristine LiNiO2.

Hierarchical porous nitrogen,oxygen,and phosphorus ternary doped hollow biomass carbon spheres for high-speed and long-life potassium storage

Limited lithium resources have promoted the exploration of new battery technologies.Among them,potassium-ion batteries are considered as promising alternatives.At present,commercial graphite and other carbon-based materials have shown good prospects as anodes for potassium-ion batteries.However,the volume expansion and structural collapse caused by periodic K+insertion/extraction have severely restricted further development and application of potassium-ion batteries.A hollow biomass carbon ball(NOP-PB)ternarily doped with N,O,and P was synthesized and used as the negative electrode of a potassium-ion battery.X-ray photoelectron spectroscopy,Fourier‐transform infrared spectroscopy,and transmission electron microscopy confirmed that the hollow biomass carbon spheres were successfully doped with N,O,and P.Further analysis proved that N,O,and P ternary doping expands the interlayer distance of the graphite surface and introduces more defect sites.DFT calculations simultaneously proved that the K adsorption energy of the doped structure is greatly improved.The solid hollow hierarchical porous structure buffers the volume expansion of the potassium insertion process,maintains the original structure after a long cycle and promotes the transfer of potassium ions and electrons.Therefore,the NOP‐PB negative electrode shows extremely enhanced electrochemical performance,including high specific capacity,excellent long‐term stability,and good rate stability.

Synthesis and Characterization of LiCo_xMn_(2-x)O_4 Cathode Materials

LiCoxMn2.04 cathode materials for lithium ion batteries were synthesized by mechanical activation-solid state reaction at 750 ℃ for 24 h in air atmosphere, and their crystal structure, morphology, element composition and electrochemical performance were characterized with XRD, SEM, ICP-AES and charge-discharge test. The experimental results show that all samples have a single spinel structure, well formed crystal shape and uniformly particle size distribution. The lattice parameters of LiCo Mn2-xO4 decrease and the average oxidation states of manganese ions increase with an increase in Co content. Compared with pure LiMn2O4, the LiCo Mn2xO4 （x=0.03-0.12） samples show a lower special capacity, but their cycling life are improved. The capacity loss of LiCo009Mn191O4 and LiCo0.1Mn1.88O4 is only 1.85% and 0.95%, respectively, after the 20th cycle. The improvement of the cycle performance is attributed to the substitution of Co at the Mn sites in the spinel structure, which suppresses the Jahn-Teller distortion and improves the structural stability.

Photoluminescence properties of Ce^(3+) and Mn^(2+)-activated Ba_9Sc_2Si_6O_(24) phosphor for white light emitting diodes

A single-phased silicate compound （Ba1-xCex）9（Sc1-yMny）2Si6O24 was prepared by solid-state reaction at high temperature. From powder X-ray diffraction （XRD） analysis, the formation of Ba9Sc2Si6O24 with an R3 space group was confirmed. In the photoluminescence spectra under ultraviolet （UV） ray excitation, the Ba9Sc2Si6O24：Ce3＋,Mn2＋ phosphor emits two distinctive color light bands： a blue one originating from Ce3＋and a red one caused by Mn2＋. The energy transfer process from Ce3＋ to Mn2＋ was confirmed, the critical radius as well as the transfer efficiency was calculated, and the energy transfer mechanism was discussed. In addition, the decay-time testing indicates that the energy transfer efficiencies from Ce（1） to Mn2＋ and Ce（2） to Mn2＋ are different. The emission chromaticity of Ba9Sc2Si6O24：Ce3＋,Mn2＋ phosphor could be tuned from blue to red by altering the Ce3＋/Mn2＋ concentration ratio.

Structural and Electrical Properties of Niobium Doped Y_0.6Gd_0.4Ba_2-xNb_xCu₃O_7-ySuperconductors

Polycrystalline samples of Y0.6Gd0.4Ba2-xNbxCu3O7-y(YGBNCO) with different Nb contents (x = 0.05, 0.10, 0.15, 0.20, and 0.25) were prepared using the usual solid state reaction technique. The structure for all samples was characterized by XRD and SEM. The electrical properties were measured by the FPP method in the temperature range from 70 to 130 K. The lattice constant of b remains almost unchanged and a and c increases with the increase of Nb content with x ≤ 0.10. The zero resistance transition temperature and Jc decrease with increasing Nb content. But superconductivity did not suppress. As the Nb content in the samples increases, it gives a diffused phase indicating a niobium perovskite phase and it is a small amount of unidentified phase.

Influence of Gd_2O_3 and Yb_2O_3 Co-doping on Phase Stability,Thermo-physical Properties and Sintering of 8YSZ

The role of multicomponent rare earth oxides in phase stability, thermophysical properties and sintering for ZrO2-based thermal barrier coatings （TBCs） materials is investigated. 8YSZ codoped with 3 mol% Gd2O3 and 3 mol% Yb2O3 （GYb-YSZ） powders are synthesized by solid state reaction for 24 h at various temperatures. As temperature increases, stabilizers are dissolved into zirconia matrix gradually. Synthesized at 1 500 °C, GYb-YSZ is basically composed of cubic phase. GYb-YSZ exhibits excellent phase stability and sinters lower than 8YSZ by nearly three times. The thermal conductivity of GYb-YSZ is much lower than that of 8YSZ, and the thermal expansion coefficient of GYb-YSZ is comparable to that of 8YSZ. The influence of Gd2O3 and Yb2O3 co-doping on phase stability, thermal conductivity and sintering of 8YSZ is discussed.

Effect of Cu Co-doping on the Magnetism of Zn_(0.95)Co_(0.05)O Films

Zno.95-xCoo.05CuxO （atomic ratio, x = 0-8%） thin films are fabricated on Si（lll） substrate by reactive magnetron sputtering method. Detailed characterizations indicate that the doped Cu ions substitute the Zn2＋ ions in ZnO lattice. The doped Cu ions are in ＋1 and ＋2 mixture valent state. The ferromagnetism of the Zno.95-xCoo.o5CuxO film increases gradually with the increase of the Cu＋ ion concentration till x = 6%, but decreases for higher Cu concentration. Experimental results indicate that the increase of ferromagnetism is not owing to the magnetic contribution of Cu＋ ions themselves, but owing to the enhancement of magnetic interaction between Co2＋ ions, which suggests that p-type doping of Cu＋ ions plays an important role in mediating the ferromagnetic coupling between Co ions.

Electronic structure and optical properties of N-Zn co-doped-Ga_2O_3

The electronic structure and optical properties of N-doped β-Ga2O3 and N-Zn co-doped β-Ga2O3 are investigated by the first-principles calculation. In the N-Zn co-doped β-Ga2O3 system, the lattice parameters of a, b, c, V decrease and the total energy Etot,l increases in comparison with N-doped β-Ga2O3. The calculated ionization energy of N-Zn co-doped β-Ga2O3 is smaller than that of N-doped β-Ga2O3. Two shallower acceptor impurity levels are introduced in N-Zn co-doped β-Ga2O3. Compared with N-doped β-Ga2O3, the major absorption peak is red-shifted and the impurity absorption edge is blue-shifted for N-Zn co-dopedβ-Ga2O3. The results show that the N-Zn co-doped β-Ga2O3 is found to be a better method to push p-type conductivity in β-Ga2O3.

Highly N/O co-doped ultramicroporous carbons derived from nonporous metal-organic framework for high performance supercapacitors

A new nonporous Zn-based metal-organic framework(NPMOF) synthesized from a high nitrogencontaining rigid ligand was converted into porous carbon materials by direct carbonization without adding additional carbon sources.A series of NPMOF-derived porous carbons with very high N/O contents(24.1% for NPMOF-700,20.2% for NPMOF-800,15.1% for NPMOF-900) were prepared by adjusting the pyrolysis temperatures.The NPMOF-800 fabrica ted electrode exhibits a high capacitance of220 F/g and extremely large surface area normalized capacitance of 57.7 μF/cm~2 compared to other reported MOF-derived porous carbon electrodes,which could be attributed to the abundant ultramicroporosity and high N/O co-doping.More importantly,symmetric supercapacitor assembled with the MOF-derived carbon manifests prominent stability,i.e.,99.1 % capacitance retention after 10,000 cycles at 1.0 A/g.This simple preparation of MOF-derived porous carbon materials not only finds an application direction for a variety of porous or even nonporous MOFs,but also opens a way for the production of porous carbon materials for superior energy storage.