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Polysulfide regulation by defect-modulated Ta_(3)N_(5-x) electrocatalyst toward superior room-temperature sodium-sulfur batteries

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Science Bulletin 2024年第2期69卷 197-208页

作者： Zhen Zhang Dan Luo Jun Chen Chuyin Ma Matthew Li Haoze Zhang Renfei Feng Rui Gao Haozhen Dou Aiping Yu Xin Wang Zhongwei Chen Department of Chemical Engineering Waterloo Institute for NanotechnologyUniversity of WaterlooWaterloo N2L 3G1Canada Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023China South China Academy of Advanced Optoelectronics&International Academy of Optoelectronics at Zhaoqing South China Normal UniversityGuangzhou 510006China Chemical Sciences and Engineering Division Argonne National LaboratoryLemont 60439USA Canadian Light Source Saskatoon S7N 2V3Canada

Resolving low sulfur reaction activity and severe polysulfide dissolution remains challenging in metalsulfur batteries.Motivated by a theoretical prediction,herein,we strategically propose nitrogenvacancy tantalum nitride(Ta3N5-x)impregnated inside the interconnected nanopores of nitrogendecorated carbon matrix as a new electrocatalyst for regulating sulfur redox reactions in roomtemperature sodium-sulfur batteries.Through a pore-constriction mechanism,the nitrogen vacancies are controllably constructed during the nucleation of Ta3N5-x.The defect manipulation on the local environment enables well-regulated Ta 5d-orbital energy level,not only modulating band structure toward enhanced intrinsic conductivity of Ta-based materials,but also promoting polysulfide stabilization and achieving bifunctional catalytic capability toward completely reversible polysulfide conversion.Moreover,the interconnected continuous Ta3N5-x-in-pore structure facilitates electron and sodium-ion transport and accommodates volume expansion of sulfur species while suppressing their shuttle behavior.Due to these attributes,the as-developed Ta3N5-x-based electrode achieves superior rate capability of 730 mAh g-1 at 3.35 A g-1,long-term cycling stability over 2000 cycles,and high areal capacity over 6 mAh cm-2 under high sulfur loading of 6.2 mg cm-2.This work not only presents a new sulfur electrocatalyst candidate for metal-sulfur batteries,but also sheds light on the controllable material design of defect structure in hopes of inspiring new ideas and directions for future research.

关键词： Tantalum nitride nitrogen defects Sodium-sulfur batteries Electrocatalysts Polysulfide conversion

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Tailoring sulfur-doped and nitrogen-defective carbon nitride nanosheets for efficient photo-controlled radical polymerizations

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Science China Chemistry 2024年第7期67卷 2325-2334页

作者： Xue Li Meng Kai Xu Yuan Huang Tao Cai Key Laboratory of Biomedical Polymers of Ministry of Education College of Chemistry and Molecular SciencesWuhan UniversityWuhan 430072China Wuhan University Shenzhen Research Institute Shenzhen 518057China

Despite the challenges that remain,the synergistic adjustment of various microstructures and photochemical parameters of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic reactions holds promises for improving catalytic efficiency and reducing energy consumption.Herein,sulfur-doped and nitrogen-defective g-C_(3)N_(4)(n-SC_(3)N_(x))nanosheets were designed and elaborately synthesized.The resultant n-SC_(3)N_(x)possessed a precisely defined 2D layer structure with extensive porosity and incremental specific surface area.Enhanced photoinduced electron transfer-reversible addition-fragmentation chain transfer(PET-RAFT)polymerization of vinyl monomers with low dispersity,excellent temporal control and high chain-end fidelity was achieved under mild blue light irradiation in a nondegassed system.Owing to their ultrathin nanostructures with nitrogen defects and sulfur dopants,n-SC_(3)N_(x)was capable of catalyzing RAFT polymerization in aqueous solutions at significantly accelerated rates,which were nearly 8 times faster compared to bulk g-C_(3)N_(4).The ease of separation and efficient reusability in subsequent polymerizations was enabled by the heterogeneous nature of n-SC_(3)N_(x).The appeal of this approach was illustrated by the fact that utilizing a reusable and metal-free photocatalyst in aqueous environments allowed for the synthesis of polymers with molecular weight up to 300 kg mol-1and a dispersity of 1.32.

关键词： graphitic carbon nitride nitrogen defects sulfur dopants PET-RAFT polymerization recyclability

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Defect-rich porous tubular graphitic carbon nitride with strong adsorption towards lithium polysulfides for high-performance lithium-sulfur batteries

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Journal of Materials Science & Technology 2022年第20期115卷 140-147页

作者： Heng Ma Xin Liu Ning Liu Yan Zhao Yongguang Zhang Zhumabay Bakenov Xin Wang School of Materials Science and Engineering Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control TechnologyHebei University of TechnologyTianjin 300130China Institute of Batteries LLC School of Engineering and Digital SciencesNational Laboratory AstanaNazarbayev University53 Kabanbay Batyr AvenueNur-Sultan 010000Kazakhstan South China Academy of Advanced Optoelectronics International Academy of Optoelectronics at ZhaoqingSouth China Normal UniversityGuangzhou 510006China

The commercialization of the lithium-sulfur(Li-S)batteries is severely hampered by the shuttle effect and sluggish kinetics of lithium polysulfides(Li PSs).In this study,porous tubular graphitic carbon nitride(PTCN)was synthesized as the sulfur host by hydrothermal treatment,thermal shock and etching methods.By etching technology,the hollow nanotube tentacles grow on the tube wall of PTCN,the mesoporous appears on the inner wall,and a large number of nitrogen defects are introduced.The verticallyrooted hollow nanotube tentacles on the PTCN surface facilitate electron conduction for sulfur redox reactions.The hollow and porous architecture exposes plentiful active interfaces for accelerated redox conversion of polysulfide.Furthermore,the nitrogen defects in PTCN enable more excellent intrinsic conductivity,higher adsorbability and conversion catalytic activity to Li PSs.Based on the above synergetic effect,the batteries with PTCN/S cathodes realize a high discharge capacity of 504 m Ah g^(-1) at 4 C and a stable cycling behavior over 500 cycles with a low capacity decay of 0.063%per cycle.The results indicate a promising approach todesigning a high performance electrode material for Li-S batteries.

关键词： Lithium-sulfur batteries Porous tubular graphitic carbon nitride Sulfur host nitrogen defects

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Competitive role of nitrogen functionalities of N doped GO and sensitizing effect of Bi_(2)O_(3)QDs on TiO_(2)for water remediation

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Journal of Environmental Sciences 2021年第10期33卷 107-119页

作者： Saima Noor Shamaila Sajjad Sajjad Ahmed Khan Leghari Cristina Flox Saeed Ahmad International Islamic University Islamabad 44000Pakistan Department of Chemistry and Materials Science Aalto UniversityEspoo 16100Fl-00076Finland Pakistan Institute of Engineering and Applied Sciences Islamabad 44000Pakistan Department of Applied Physics Aalto UniversityEspoo 15100Fl-00076Finland

The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots(BQDs)doped TiO_(2)with nitrogen doped graphene oxide(NGO)nanocomposite(NGO/BQDs-TiO_(2))was fabricated.It was used for degradation of organic pollutants like 2,4-dichlorophenol(2,4-DCP)and stable dyes,i.e.Rhodamine B and Congo Red.X-ray diffraction(XRD)profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal structure.The characteristic diffraction peaks of TiO_(2)and its composites showed crystalline anatase TiO_(2).Morphological images represent spherical shaped TiO_(2)evenly covered with BQDs spread on NGO sheet.The surface linkages of NO-O-Ti,C-O-Ti,Bi-O-Ti and vibrational modes are observed by Fourier transform infrared spectroscopy(FTIR)and Raman studies.BQDs and NGO modified TiO_(2)results into red shifting in visible region as studied in diffused reflectance spectroscopy(DRS).NGO and BQDs in TiO_(2)are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence(PL)intensities.X-ray photoelectron spectroscopy(XPS)shows that no peak related to C-O in NGO/BQDs-TiO_(2)is observed.This indicated that doping of nitrogen into GO has reduced some oxygen functional groups.nitrogen functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic pollutants.Intermediate byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography(HPLC).Study of radical scavengers indicated that O_(2)^(·-) has significant role for degradation of 2,4-DCP.Our investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.

关键词： Bi_(2)O_(3)quantum dots nitrogen doped graphene oxide nitrogen defects TiO_(2) 2,4-Dichlorophenol Water treatment

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Highly efficient visible photocatalytic disinfection and degradation performances of microtubular nanoporous g-C3N4 via hierarchical construction and defects engineering

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Journal of Materials Science & Technology 2020年第14期47卷 133-143页

作者： Jing Xu Zhouping Wang Yongfa Zhu State Key Laboratory of Food Science and Technology Jiangnan UniversityWuxi 214122China School of Food Science and Technology Jiangnan UniversityWuxi 214122China International Joint Laboratory on Food Safety Jiangnan UniversityWuxi 214122China Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province Jiangnan UniversityWuxi 214122China Department of Chemistry Tsinghua UniversityBeijing 100084China

Herein,microtubular nanoporous g-C3N4(TPCN)with hierarchical structure and nitrogen defects was prepared via a facile self-templating approach.On one hand,the hexagonal tubular structure can facilitate the light reflection/scattering,provide internal/external active sites,and endow the electron with oriented transfer channels.The well-developed nanoporosity can result in large specific surface area and abundant accessible channels for charge migration.On the other hand,the existence of nitrogen vacancies can improve the light harvesting(>450 nm)and prompt charge separation by acting as the shallow charge traps.More NHxgroups in g-C3N4 framework can promote the interlayer charge transport by generating hydrogen-bonding interaction between C3N4 layers.Therefore,TPCN possessed highly efficient visible photocatalytic performances to effectively inactivate Escherichia coli(E.coli)cells and thoroughly mineralize organic *** with the optimum bactericidal efficiency can completely inactivated5×10^6 cfu mL^-1 of E.coli cells after 4 h of irradiation treatment,while about 74.4%of E.coli cells were killed by bulk g-C3N4(BCN).Meanwhile,the photodegradation rate of TPCN towards methylene blue,amaranth,and bisphenol A were almost 3.1,2.5 and 1.6 times as fast as those of BCN.Furthermore,h^+and·O2^- were the reactive species in the photocatalytic process of TPCN system.

关键词： g-C3N4 photocatalyst Hierarchical structure nitrogen defects Disinfection Degradation

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