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Formation and fluorescent mechanism of red emissive carbon dots from o-phenylenediamine and catechol system

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Light(Science & Applications) 2022年第11期11卷 2687-2697页

作者： Pengfei Li Shanshan Xue Lu sun Xupeng Zong Li An Dan Quo Xiayan Wang zaicheng sun Center of Excellence for Environmental Safety and Biological Effects Bejing Key Laboratory for Green Catalysis and SeparationDepartment of ChemistryBeijing Universityof Technology100124 BejingChina

Carbon dots(CDs)as the advancing fluorescent carbon nanomaterial have superior potential and prospective.However,the ambiguous photoluminescence(PL)mechanism and intricate structure-function relationship become the greatest hindrances in the development and applications of CDs.Herein,red emissive CDs were synthesized in high yield from O-phenylenediamine(oPD)and catechol(CAT).The PL mechanism of the CDs is considered as the molecular state fluorophores because 5,14-dihydroquinoxalino[2,3-b]phenazine(DHQP)is separated and exhibits the same PL properties and behavior as the CDs.These include the peak position and shape of the PL emission and PL excitation and the emission dependence on pH and solvent polarity.Both of them display close PL lifetime decays.Based on these,we deduce that DHQP is the fluorophore of the red emissive CDs and the PL mechanism of CDs is similar to DHQP.During the PL emission of CDs,the electron of the molecule state can transfer to CDs.The formation process of DHQP is further confirmed by the reaction intermediates(phthalazine,dimers)and oPD.These findings provide insights into the PL mechanism of this type of CDs and may guide the further development of tunable CDs for tailored properties.

关键词： properties mechanism catechol

Wettability control of defective TiO_(2)with alkyl acid for highly efficient photocatalytic ammonia synthesis

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Nano Research 2023年第8期16卷 10770-10778页

作者： Renquan Guan Xueying Cheng Yunning Chen Zhengkai Wu Zhao Zhao Qingkun Shang Yingnan sun zaicheng sun Faculty of Chemistry Northeast Normal UniversityChangchun 130024China Faculty of Physics Northeast Normal UniversityChangchun 130024China Instrumental Analysis Center Yancheng Teachers UniversityYancheng 224007China Center of excellence for environmental safety and biological effects Beijing Key Lab for Green Catalysis and SeparationFaculty of Environment and lifeBeijing University of TechnologyBeijing 100124China

Ammonia is an important chemical raw material and non-carbon-based fuel.Photocatalytic ammonia production technology as a mild alternative to the traditional Harbor–Bosch route is carried out at the air,liquid,and solid three-phase interface.Promoting the activation of N_(2),depressing hydrogen evolution reaction(HER),and increasing the local N_(2) concentration around the catalyst surface are critical factors in achieving high conversion efficiency.In this paper,we proposed that defective TiO_(2)is surfacemodified by alkyl acids with different carbon chain lengths(C_(2),C_(5),C_(8),C_(11),and C_(14))to tune the catalyst surface properties.The defect sites greatly promote N_(2) adsorption and activation.The wettability of the catalyst can be regulated from hydrophilic to hydrophobic by the length of the alkyl chain.The hydrophobic surface enhances the N_(2) adsorption and increases the local N_(2) concentration due to its aerophile.Meanwhile,it depresses the proton adsorption and HER.Overall,the nitrogen reduction reaction(NRR)is greatly promoted.Among the series of samples,they present a systematic change and have a maximal NRR performance for n-octanoic acid-defective TiO_(2)(C8-Vo-TiO_(2);Vo=oxygen vacancy).The rate of ammonia production can be as high as 392μmol·g^(−1)·h^(−1).This work provides a new strategy for efficient ammonia synthesis at the three-phase interface using photocatalyst technology.

关键词： aerophilic modification alkyl acids defective TiO_(2) photocatalytic ammonia synthesis

Recent advances of carbon dots as new antimicrobial agents

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SmartMat 2022年第2期3卷 226-248页

作者： Pengfei Li Lu sun Shanshan Xue Dan Qu Li An Xiayan Wang zaicheng sun Department of Chemistry and Biology Beijing Key Laboratory for Green Catalysis and SeparationCenter of Excellence for Environmental Safety and Biological EffectsBeijing University of TechnologyBeijingChina

Due to the COVID-19 pandemic,many rapid antimicrobial agents have developed intensively.Carbon dots(CDs),a new type of carbon-based nanomaterials,shows great potential against emerging infectious diseases and antimicrobial-resistant infections due to their unique optical properties,excellent biocompatibility,and easy surface modification.With the definition of the CDs structure and properties,synthesis,and characteristic technology improvement,the research on the CDs as antimicrobial agents has made significant progress.However,the lack of high repeatable and exact preparation methods,and the regular antimicrobial activity make it far from practical application.In this review,we summarize the most recent progress and challenges of CDs antimicrobial.First,an overview of the characteristics and properties is given,and the advantage of CDs applied to antimicrobial is further discussed.Then,it focuses on research progress on antimicrobial mechanisms under different conditions,the critical factors affecting their antimicrobial activity,and the practical antimicrobial applications.Finally,the main challenges and future research perspectives of antimicrobial CDs are proposed.

关键词： antimicrobial antimicrobial activity carbon dots photodynamic effect reactive oxygen species

The critical factors of photocatalytic H2 production from seawater by using TiO_(2)as photocatalyst

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Nano Research 2023年第4期16卷 4620-4624页

作者： Yaqian He Pengfei Li Wenning Liu Li An Dan Qu Xiayan Wang zaicheng sun Beijing Key Laboratory for Green Catalysis and Separation Center of Excellence for Environmental Safety and Biological EffectsFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China

The solar H_(2)generation directly from natural seawater is a sustainable way of green energy.However,it is limited by a low H_(2)generation rate even compared to fresh water.In this report,TiO_(2)is chosen as a model photocatalyst to disclose the critical factor to deteriorate the H_(2)generation rate from seawater.The simulated seawater(SSW),which is composed of eight ions(Na^(+),K^(+),Ca^(2+),Mg^(2+),Cl^(−),Br^(−),SO_(4)^(2−),and CO_(3)^(2−)),is investigated the effect of each ion on the H_(2)production.The results indicate that all ions have a negative effect at the same concentration as in the seawater except Br−.The CO_(3)^(2−)has the most serious deterioration,and the H_(2)production rate lowers near 40%even at[CO_(3)^(2−)]of 1.5 mmol·L^(−1).The H_(2)production rate can be recovered to 85%if the CO_(3)^(2−)is excluded from the SSW.To understand the reason,the zeta potential of the TiO_(2)treated with different ions aqueous solution reveals that the zeta potential decreases when it is treated with CO_(3)^(2−)and SO_(4)^(2−)due to they can adsorb on the surface of TiO_(2)nanoparticles.Fourier transform infrared(FTIR)and thermogravimetric analysis-mass spectroscopy(TGA-MS)further confirm that the adsorbed ion is mainly from CO_(3)^(2−).Since the pH of seawater is about 8.9 between pKa1(6.37)and pKa2(10.3)of H_(2)CO3,the CO_(3)^(2−)should exist in the form of HCO3−in the seawater.We proposed a simple method to remove the adsorbed HCO3−from the TiO_(2)surface by adjusting the pH below the pKa1.The results indicate that if a trace amount of HCl(adjusting pH~6.0)is added to the SSW,the H_(2)production rate can be recovered to 85%of that in pure water.

关键词： seawater H_(2)production rate adsorb ions pH

Fe_(2)Mo_(3)O_(8)/XC-72 electrocatalyst for enhanced electrocatalytic nitrogen reduction reaction under ambient conditions

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Nano Research 2022年第7期15卷 5940-5945页

作者： Guohua Liu Lijuan Niu Zhixue Ma Li An Dan Qu Dandan Wang Xiayan Wang zaicheng sun Beijing Key Laboratory for Green Catalysis and Separation Center of Excellence for Environmental Safety and Biological EffectsFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education Jilin Normal UniversityChangchun 130103China

To perform the electrochemical nitrogen reduction reaction(NRR)under milder conditions for sustainable ammonia production,electrocatalysts should exhibit high selectivity,activity,and durability.However,the key restrictions are the highly stable N≡N triple bond and the competitive hydrogen evolution reaction(HER),which make it difficult to adsorb and activate N2 on the surface of electrocatalysts,leading to a low ammonia yield and Faraday efficiency.Inspired by the enzymatic nitrogenase process and using the Fe-Mo as the active center,here we report supported Fe_(2)Mo_(3)O_(8)/XC-72 as an effective and durable electrocatalyst for the NRR.Fe_(2)Mo_(3)O_(8)/XC-72 exhibited NRR activity with an NH3 yield of 30.4μg·h^(−1)·mg^(−1)(−0.3 V)and a Faraday efficiency of 8.2%(−0.3 V).Theoretical calculations demonstrated that the electrocatalytic nitrogen fixation mechanism involved the Fe atom in the Fe_(2)Mo_(3)O_(8)/XC-72 electrocatalyst acting as the main active site in the enzymatic pathway(*NH2→*NH3),which activated nitrogen molecules and promoted the NRR performance.

关键词： nitrogen reduction reaction(NRR) Fe_(2)Mo_(3)O_(8)/XC-72 electrocatalyst density functional theory calculations

Surface hydrophobic modification enhanced catalytic performance of electrochemical nitrogen reduction reaction

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Nano Research 2022年第5期15卷 3886-3893页

作者： Lijuan Niu Ziwen Liu Guohua Liu Mengxuan Li Xupeng Zong Dandan Wang Li An Dan Qu Xiaoming sun Xiayan Wang zaicheng sun Beijing Key Laboratory for Green Catalysis and Separation Center of Excellence for Environmental Safety and Biological EffectsFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China State Key Laboratory of Chemical Resource Engineering College of Energy Beijing Advanced Innovation Center for Soft Matter Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education Jilin Normal UniversityChangchun 130103China

Electrocatalytic nitrogen reduction reaction(NRR)is a sustainable approach for NH_(3)production with low energy consumption.However,competing hydrogen reduction reaction(HER)in aqueous solution results in low NH_(3)production and Faraday efficiency(FE).Here,MoS_(2)nanostructures with a hydrophobic surface are synthesized by alkyl thiols modification.Aerophilic and hydrophobic surface facilitates an efficient three-phase contact of N_(2),H_(2)O,and catalyst.Thus,localized concentrated N_(2)molecules can overcome the mass transfer limitation of N2 and depress the HER due to lowering the proton contacts.Although the active-sites decrease with the increase of the alkyl chain since the thiol may cover the active site,the optimized electrocatalyst achieves NH_(3)yield of 12.86×10^(-11)mol·cm^(-2)·s^(-1)at-0.25 V and 22.23%FE,which are 4.3 and 24 times higher than those of MoS2-CP electrocatalyst,respectively.The increased catalytic performance is attributed to the high N_(2)adsorption and depressed HER.

关键词： nitrogen reduction reaction MoS_(2)electrocatalyst hydrophobic modification density functional theory calculations

Synergistic CO_(2)reduction and tetracycline degradation by CuInZnS-Ti_(3)C_(2)T_(x)in one photoredox cycle

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Nano Research 2022年第9期15卷 8010-8018页

作者： Lijing Wang Zhan Zhang Renquan Guan Dandan Wu Weilong Shi Limin Yu Pan Li Wei Wei Zhao Zhao zaicheng sun Henan Engineering Center of New Energy Battery Materials Henan D&A Engineering Center of Advanced Battery MaterialsCollege of Chemistry and Chemical EngineeringInstitute of Architectural EngineeringShangqiu Normal UniversityShangqiu 476000China Faculty of Physics Faculty of ChemistryNortheast Normal UniversityChangchun 130024China Center of excellence for environmental safety and biological effects Beijing Key Lab for Green Catalysis and SeparationDepartment of Chemistry and Chemical EngineeringCollege of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

Optimizing photocatalytic CO_(2)reduction with simultaneous pollutant degradation is highly desired.However,the photocatalytic efficiency is restricted by the unmatched redox ability,high carriers’recombination rate,and lack of reactive sites of the present photocatalysts.Herein,the CuInZnS-Ti_(3)C_(2)T_(x)hybrid with matched redox ability and suitable CO_(2)adsorption property was rationally synthesized.The nucleation and growth process of CuInZnS was interfered by the addition of Ti_(3)C_(2)T_(x)with a negative charge,resulting in thinner nanosheets and richer reactive sites.Besides,the Schottky heterojunction built in the hybrid simultaneously improved the photoexcited charge transfer property,sunlight absorption range,and CO_(2)adsorption ability.Consequently,upon exposure to sunlight,CuInZnS-Ti_(3)C_(2)T_(x)exhibited an efficient photocatalytic CO_(2)reduction performance(10.2μmol·h^(−1)·g^(−1))with synergetic tetracycline degradation,obviously higher than that of pure CuInZnS.Based on the combination of theoretical calculation and experimental characterization,the photocatalytic mechanism was investigated comprehensively.This work offers a reference for the remission of worldwide energy shortage and environmental pollution problems.

关键词： CuInZnS-Ti_(3)C_(2)T_(x) photocatalysis CO_(2)reduction tetracycline degradation

Effect on electrochemical reduction of nitrogen to ammonia under ambient conditions: Challenges and opportunities for chemical fuels

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Journal of Energy Chemistry 2021年第10期30卷 304-318,I0009页

作者： Lijuan Niu Li An Xiayan Wang zaicheng sun Beijing Key Laboratory for Green Catalysis and Separation Center of Excellence for Environmental Safety and Biological EffectsFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China

The nitrogen cycle plays an important role in nature,but N-containing products cannot meet human needs.The electrochemical synthesis of ammonia under ambient conditions has attracted the interest of many researchers because it provides a clean and pollution-free synthesis method;however,it has certain difficulties,including a high activation energy,multiple electron transfer,and hydrogenation.Thermodynamic factors limit the selectivity and activity of ammonia synthesis techniques.This review summarizes progress in the electrochemical synthesis of ammonia from theory and experiment.Theoretically,the reduction of nitrogen molecules is analyzed using orbit theory and the thermodynamic reaction pathways.Experimentally,we first discuss the effect of the experimental setup on the nitrogen reduction reaction,and then the four critical of catalysts,including size,electronic,coordination,and orientation effects.These issues must be considered to produce highly-efficient catalysts for electrochemical nitrogen reduction(eNRR).This review provides an overview of the eNRR to enable future researchers to design rational catalysts.

关键词： Nitrogen reduction reaction NRR Electrocatalyst Nitrogen-fixing

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长波长发射碳点合成、调控及应用研究进展

发光学报 2024年第4期45卷 534-556页

作者：陈劲良曲丹赵雯辛安丽孙再成北京工业大学化学与生命科学学院环境科学与工程学院绿色催化与分离北京市重点实验室环境安全与生物效应中心北京100124

近年来,随着碳点在合成路线、反应机理、光学性质等方面的发展,大量的工作聚焦于红光或近红外光等长波长发射的碳点。长波长是指发射范围在600~1800 nm的红色或近红外光谱区,相比短波长碳点,其具有深组织穿透、较小自荧光、长荧光寿命... 详细信息

近年来,随着碳点在合成路线、反应机理、光学性质等方面的发展,大量的工作聚焦于红光或近红外光等长波长发射的碳点。长波长是指发射范围在600~1800 nm的红色或近红外光谱区,相比短波长碳点,其具有深组织穿透、较小自荧光、长荧光寿命以及光损伤小等特点,能够进一步应用在生物医学治疗、光电子以及光学器件制备等领域。因此,深入探究长波长发射碳点的设计和合成对于其发展和广泛应用具有重要意义。本文综述了近年来长波长发射碳点的研究进展,从碳源选择和光学性质调控两个方面介绍了长波长发射碳点的设计与制备。选择氨基较多的脂肪族化合物和具有共轭结构的芳香化合物,以及通过调控有效共轭长度、表面修饰和杂原子掺杂等方法来调控其光学性质。最后,阐述了长波长碳点在生物医学、LED光学器件和加密防伪等一些领域的最新研究和未来的挑战。

关键词：长波长发射碳点光学性质应用