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Engineering nanoporous and solid core-shell architectures of lowplatinum alloy catalysts for high power density PEM fuel cells

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Nano Research 2022年第7期15卷 6148-6155页

作者： Yongqiang Kang Jiaqi Wang Yinping Wei Yongle Wu dongsheng xia Lin Gan Institute of Materials Research Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

Low-platinum(Pt)alloy catalysts hold promising application in oxygen reduction reaction(ORR)electrocatalysis of protonexchange-membrane fuel cells(PEMFCs).Although significant progress has been made to boost the kinetic ORR mass activity at low current densities in liquid half-cells,little attention was paid to the performance of Pt-based catalysts in realistic PEMFCs particularly at high current densities for high power density,which remains poorly understood.In this paper,we show that,regardless of the kinetic mass activity at the low current density region,the high current density performance of the low-Pt alloy catalysts is dominantly controlled by the total Pt surface area,particularly in low-Pt-loading H_(2)–air PEMFCs.To this end,we propose two different strategies to boost the specific Pt surface area,the post-15-nm dealloyed nanoporous architecture and the sub-5-nm solid core–shell nanoparticles(NPs)through fluidic-bed synthesis,both of which bring in comparably high mass activity and high Pt surface area for large-current-density performance.At medium current density,the dealloyed porous NPs provide substantially higher H_(2)–air PEMFC performance compared to solid core–shell catalysts,despite their similar mass activity in liquid half-cells.Scanning transmission electron microscopy images combined with electron energy loss spectroscopic imaging evidence a previously unreported“semi-immersed nanoporous-Pt/ionomer”structure in contrast to a“fully-immersed core–shellPt/ionomer”structure,thus favoring O_(2) transport and improving the fuel cell performance.Our results provide new insights into the role of Pt nanostructures in concurrently optimizing the mass activity,Pt surface area and Pt/Nafion interface for high power density fuel cells.

关键词： low-platinum alloy catalyst nanoporosity proton-exchange-membrane fuel cells power density triple-phase boundary

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Performance and mechanism of carbamazepine removal by FeS-S_(2)O_(8)^(2–)process:experimental investigation and DFT calculations

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Frontiers of Environmental Science & Engineering 2023年第9期17卷 209-220页

作者： Xuejun Long Jun Luo Zhenxing Zhong Yanxu Zhu Chunjie Zhang Jun Wan Haiyan Zhou Beiping Zhang dongsheng xia College of Environmental Engineering Wuhan Textile UniversityWuhan 430200China Engineering Research Center for Clean Production of Textile Printing and Dyeing(Ministry of Education) Wuhan Textile UniversityWuhan 430073China Central&Southern China Municipal Engineering Design and Research Institute Co. Ltd.Wuhan 430010China Soil Environmental Institute Guangdong Provincial Academy of Environmental ScienceGuangzhou 510045China School of Environmental Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

As persulfate(S_(2)O_(8)^(2-))is being increasingly used as an alternative oxidizing agent,developing lowcost and eco-friendly catalysts for efficient S_(2)O_(8)^(2-)activation is potentially useful for the treatment of wastewater containing refractory organic pollutant.In this study,the degradative features and mechanisms of carbamazepine(CBZ)were systematically investigated in a novel FeS-S_(2)O_(8)^(2-)process under near-neutral conditions.The results exhibited that CBZ can be effectively eliminated by the FeS-S_(2)O_(8)^(2-)process and the optimal conditions were:250 mg/L FeS,0.5 mmol/L S_(2)O_(8)^(2-),and pH=6.0.The existence of Cl^(−)(1 and 50 mmol/L)has little influence on the CBZ elimination,while both HCO_(3)^(−) and HPO_(4)^(2−)(1 and 50 mmol/L)significantly suppressed the CBZ removal in the FeS-S_(2)O_(8)^(2-)process.CBZ could be degraded via a radical mechanism in the FeS-S_(2)O_(8)^(2-)process,the working radical species(i.e.,SO_(4)•−and•OH)were efficiently formed via the promoted decomposition of S_(2)O_(8)^(2-)by the surface Fe2+on the FeS and the dissolved ferrous ions in solution.Based on the identified oxidized products and Fukui index calculations,a possible degradation pathway of CBZ was speculated.More importantly,a two-stage oxidation mechanism of CBZ elimination was speculated in the FeS-S_(2)O_(8)^(2-)process,the activation of S_(2)O_(8)^(2-)by the surface-active Fe(II)of FeS dominated in the initial 5 min,while homogeneous oxidation reactions played more essential parts than others in the following reaction stage(5–60 min).Overall,this study demonstrated that the FeS-S_(2)O_(8)^(2-)process is capable of removing CBZ from water efficiently.

关键词： FeS S_(2)O_(8)^(2-) Carbamazepine DFT calculations Degradation routes

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Non-woven cotton fabric based intimately coupling of photocatalysis and biodegradation system for efficient removal of Cu(Ⅱ)complex in water

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Chinese Chemical Letters 2022年第6期33卷 3127-3132页

作者： Yuxuan Ye Peng Yang Yuwei Deng Yezhi Yang Kun Zhang Yueying Wang Wenjing Shang Qiang Li Lei Sun Fei Pan dongsheng xia School of Environmental Engineering Wuhan Textile UniversityWuhan 430073China Engineering Research Center for Clean Production of Textile Dyeing and Printing Ministry of EducationWuhan 430073China

The efficient remediation of heavy metal complexes in water has become a difficult and challenging task owing to their high stability and strong mobility.In this study,a novel strategy was employed for highly efficient removal of Cu-citrate by using intimately coupled photocatalysis and biodegradation(ICPB)system with non-woven cotton fabric as a carrier.Experimental results showed that the ICPB system caused94%Cu removal,which was higher than those of single photocatalysis.After 5 cycles,Cu removal efficiency could still reach 78%within 5 h.The existence of 0–40 mg/L citrate had negligible influence,whereas the presence of 60–100 mg/L citrate exhibited a limited adverse effect on Cu removal(~70%).The decomplexation of Cu-citrate was realized via the function of free radicals and microorganisms.Two main processes,such as bio-adsorption of Cu^(2+) by microorganisms,deposition of Cu^(0) on the surface of material,played important role in Cu removal from aqueous solution.The dominant microorganisms in the system were Proteobacteria,Actinobacteria,Bacteroidetes,Chloroflexi,Chlorophyta,Planctomycetes,and Verrucomicrobia.Furthermore,the performance of ICPB system was also validated through treatment of other heavy metal complexes.This study provided a feasible strategy for the decontamination of heavy metal complexes in wastewater.

关键词： Cu complex Photocatalysis Biological treatment Non-woven cotton fabric

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Band gap tuning of g-C3N4via decoration with AgCl to expedite the photocatalytic degradation and mineralization of oxalic acid

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Journal of Environmental Sciences 2019年第10期31卷 1-12页

作者： Hanlu Shi Rui He Lei Sun Gang Cao xiangjuan Yuan dongsheng xia School of Environmental Engineering Wuhan Textile University Wuhan 430073 China Engineering Research Center for Clean Production of Textile Dyeing and Printing Ministry of Education Wuhan 430073 China

A series of functional organic-metal AgCl-decorated graphitic carbon nitride(AgCl-CNx)composites were synthesized and applied for the degradation of oxalic acid(OA)under visible light.The highest photocatalytic activity was achieved with AgCl decoration ratio of1.0(denoted as AgCl-CN1.0).The pseudo-first-order constant for OA degradation was 0.0722min-1 with the mineralization efficiency of 90.80%after 60 min reaction in the photocatalytic process with AgCl-CN1.0.A variety of characterization techniques including BrunauerEmmett-Teller,X-ray diffraction,scanning electron microscope,transmission electron microscopy,X-ray photoelectron spectroscopy,Fourier transform infrared spectra,ultraviolet-visible diffuse reflectance spectra,photoluminescence,and Mott-Schottky were utilized to elucidate the physicochemical,microstructure,and optical properties contributing to the improvement of the photocatalytic performance.The results showed that AgClCN1.0had an oblate flaky erythrocyte-like structure with a moderate band gap energy of^3.00 eV.In addition,the effects of the key parameters(i.e.,AgCl-CN1.0 dosage,initial OA concentration,solution pH,and presence of natural organic matter)on OA degradation were systematically investigated.Radical scavenger experiments indicated that photogenerated holes,electrons,superoxide anion radicals,and hydroxyl radicals were the dominant reactive species.Moreover,AgCl-CN1.0 exhibited excellent stability and reusability for OA degradation without detectable Ag+release in the solution over multiple reaction cycles.The efficient OA mineralization could be mainly ascribed to the moderate specific surface area,increased numbers of active sites,and effective interfacial charge transfer of AgCl-CN1.0.Overall,the AgCl-CN1.0 composite was demonstrated to be a highly efficient,stable,and recoverable photocatalyst.

关键词： AgCl Graphitic carbon nitride Photocatalytic degradation Oxalic acid Mechanism

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Enhanced ozonation degradation of atrazine in the presence of nano-ZnO： Performance, kinetics and effects

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Journal of Environmental Sciences 2017年第11期29卷 3-13页

作者： xiangjuan Yuan Xuan Yan Haiming Xu Dongya Li Lei Sun Gang Cao dongsheng xia School of Enuironmental Engineering Wuhan Textile University Wuhan 430073 China Engineering Research Center for Clean Production of Textile Dyeing and Printing Ministry of Education Wuhan 430073 China

Enhanced ozonation degradation of atrazine（ATZ） with nano-ZnO（nZnO） as catalyst and the influences of the operational parameters have been investigated through semi-continuous experiments in this study. The results demonstrated that the combination of ozone（O3） and nZnO showed an obvious synergetic effect and the ATZ degradation conformed to pseudo-first-order kinetics. An improvement of ATZ degradation efficiency by 41.8% and pseudo-first-order rate constant by more than a factor of four was obtained in the O3/nZnO process after 5 min of reaction compared to O3 alone. Meanwhile, the degradation efficiency of ATZ was gradually enhanced with increasing nZnO dosage and initial pH in the range from 3.0 to 8.0, and a higher amount of ATZ was degraded when the initial concentration of ATZ rose from 0.5 to 5 mg/L. Additionally, sulfate ion, chloride ion, nitrate ion and low concentrations of humic acid substances led to enhancement of the ATZ degradation. The notable decrease of ATZ removal efficiency observed in the presence of radical scavengers and the results of free radical tests indicated thatUOH is the dominant active radical species. The mechanism investigation demonstrated that the enhancement effect could be attributed to the introduction of nZnO,which could promote the utilization of O3, enhance the formation of superoxide radical, and further accelerate the production of hydrogen peroxide and the generation of OH/O2-.

关键词： Nano-ZnO Atrazine Catalytic ozonation Reaction mechanism

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青海省北川河径流量与水文地貌特征的关系分析

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北京师范大学学报（自然科学版） 2024年第1期60卷 138-147页

作者：董晋鹏赵霞陈东升青海师范大学地理科学学院青海省自然地理与环境过程重点实验室青藏高原地表过程与生态保育教育部重点实验室青海师范大学自然资源与环境建模室青海西宁青海省人民政府-北京师范大学高原科学与可持续发展研究院-高原土壤信息科学研究团队青海西宁

以北川河流域5个水文站径流量观测资料为基础,利用30 m分辨率的DEM数据提取了与径流量相关的水文地貌特征因子,通过对多年平均径流量与水文地貌特征因子之间的相关分析,经过共线性诊断筛选水文地貌特征因子,建立了线性回归方程.结果表明... 详细信息

以北川河流域5个水文站径流量观测资料为基础,利用30 m分辨率的DEM数据提取了与径流量相关的水文地貌特征因子,通过对多年平均径流量与水文地貌特征因子之间的相关分析,经过共线性诊断筛选水文地貌特征因子,建立了线性回归方程.结果表明:北川河流域从上游到下游地形趋于平坦,水系发育程度更高,汇流能力更强;影响多年平均径流量主要的宏观地形因子贡献率分别是地形湿度指数(50.66%)和地表粗糙度(44.33%),主要的微观地形因子贡献率分别是剖面曲率(36.25%)、高程(27.26%)和坡向变率(24.31%),主要的水系形态指标贡献率分别是节点连接率(54.16%)和面积高程积分(32.95%).上述结果为深入理解北川河流域的水文地貌关系提供依据,为研究其他小流域的不同水文节点,特别是上下游的水文地貌特征以及径流量与水文地貌特征的关系分析提供思路参考.

关键词：水文地貌特征径流量多元线性回归共线性诊断相关性

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LA-UNet网络模型在城市绿地遥感分类中的应用

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应用生态学报 2024年第4期35卷 1101-1111页

作者：徐亮亮马开森王霞李东胜孙华中南林业科技大学林业遥感信息工程研究中心长沙410004 林业遥感大数据与生态安全湖南省重点实验室长沙410004 南方森林资源经营与监测国家林业与草原局重点实验室长沙410004 湖南科技大学地理空间信息技术国家地方联合工程实验室湖南湘潭411201 河北省林业和草原调查规划设计院石家庄050011

城市绿地的精准识别和监测在城市规划和生态管理方面具有重要意义。城市绿地背景复杂,使用传统遥感分类技术容易出现错分粘连的问题。本研究以长沙市雨花区为研究区,高分二号(GF-2)遥感影像为数据源,提出一种基于LA-UNet模型的城市绿地... 详细信息

城市绿地的精准识别和监测在城市规划和生态管理方面具有重要意义。城市绿地背景复杂,使用传统遥感分类技术容易出现错分粘连的问题。本研究以长沙市雨花区为研究区,高分二号(GF-2)遥感影像为数据源,提出一种基于LA-UNet模型的城市绿地遥感分类方法,该方法以UNet模型为基础,引入DWTCA通道注意力机制模块提升网络对绿地信息的关注度,并使用CARAFE模块对提取特征进行上采样,实现对城市复杂背景下乔木、灌草等多种地类的精准分类。结果表明:利用标准假彩色遥感影像时,LA-UNet模型的城市绿地分类效果最优,总体准确率和平均交并比分别为96.3%和90.9%,比UNet模型分别提高2.8%和6.1%。在波茨坦公开数据集中,LA-UNet模型的总体准确率和平均交并比也同样优于UNet模型,分别提高0.9%和1.8%,表明LA-UNet模型具有较好的鲁棒性和通用性。本研究提出的LA-UNet模型能有效缓解城市绿地错分粘连问题,在城市绿地遥感分类中具有显著优势。改进后的LA-UNet模型比UNet模型具有更小的参数体积,能有效提升城市绿地分类精度。本研究将为城市绿地的精准分类及其空间分布规律研究提供方法参考。

关键词：遥感分类城市绿地高分二号 LA-UNet 注意力机制

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Activated carbon fiber mediates efficient activation of peroxymonosulfate systems:Modulation of manganese oxides and cycling of manganese species

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Chinese Chemical Letters 2023年第12期34卷 275-280页

作者： Lixi xiao Yuwei Deng Huo Zhou Fengjun Lu Chong Ke Yuxuan Ye Xuanyuan Pei dongsheng xia Fei Pan School of Environmental Engineering Wuhan Textile UniversityWuhan 430200China State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200China

Manganese oxides show a strong catalytic activity in the peroxymonosulfate(PMS)advanced oxidation process but have poor chemical stability and a propensity to cause the aggregation of nanoparticles.Here,a novel composite material(abbreviated as MnO_(x)@ACF)was synthesized,characterized,and applied.Activated carbon fiber(ACF)was selected as a carrier,which modulated the composition of manganese oxides.The results showed that MnO_(x)@ACF had a strong adsorption ability and successfully activated PMS to degrade tetracycline hydrochloride(TCH),with a removal eficiency of 89.0%in 30 min.Influencing factors such as pH and coexisting ion species were investigated,and a five-cycle test was conducted.Singlet oxygen(^(1)O_(2))was predominated in the MnO_(x)@ACF/PMS system.A possible explanatory pathway of TCH was proposed based on the results of the high performance liquid chromatography-mass spectrometry.It was concluded that this study provides a novel insight into the activation of PMS for the degradation of organic matter by carbon-loaded multivalent manganese oxides.

关键词： Activated carbon fiber Mn_(3)O_(4) MnO_(2) Singlet oxygen

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CuFe2O4@GO nanocomposite as an effective and recoverable catalyst of peroxymonosulfate activation for degradation of aqueous dye pollutants

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Chinese Chemical Letters 2019年第12期30卷 2216-2220页

作者： xiaoman Lei Menghan You Fei Pan Min Liu Peng Yang dongsheng xia Qiang Li Yanting Wang Jie Fu School of Environmental Engineering Wuhan Textile UniversityEngineering Research Centre for Clean Production of Textile Dyeing and PrintingMinistry of EducationWuhan 430073China Department of Environmental Science&Engineering Fudan UniversityShanghai 200438China

Recently,heterogeneous activation of peroxymonosulfate(PMS) to oxidatively degrade organic pollutants has been a hotspot.In the present work,copper ferrite-graphite oxide hybrid(CuFe2 O4@GO)was prepared and used as catalyst to activate PMS for degradation of methylene blue(MB) in aqueous solution.A high degradation efficiency(93.3%) was achieved at the experimental conditions of20 mg/L MB,200 mg/L CuFe2 O4@GO,0.8 mmol/L PMS,and 25℃temperature.Moreover,CuFe2 O4@GO showed an excellent reusability and stability.The effects of various operational parameters including pollutant type,solution pH,catalyst dosage,PMS dosage,pollutant concentration,temperature,natural organic matter(NOM),and inorganic anions on the catalytic degradation process were comprehensively investigated and elucidated.The further mechanistic study revealed the Cu(Ⅱ)/Cu(Ⅰ) redox couple on CuFe2 O4@GO played the dominant role in PMS activation,where both hydroxyl and sulfate radicals were generated and proceeded the degradation of pollutants.In general,CuFe2 O4@GO is a promising heterocatalyst for PMS-based advanced oxidation processes(AOPs) in wastewater treatment.

关键词： CuFe2O4@GO Peroxymonosulfate Methylene blue Sulfate radical Advanced oxidation processes

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Efficient removal of tetracycline in water by a novel chemical and biological coupled system with non-woven cotton fabric as carrier

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Chinese Chemical Letters 2021年第9期32卷 2823-2827页

作者： Peng Yang Yuxuan Ye Zidu Yan Qiang Li Kun Zhang Yezhi Yang Qiuyue Zhang Hang Yin dongsheng xia Fei Pan School of Environmental Engineering Wuhan Textile UniversityWuhan 430073China Engineering Research Center for Clean Production of Textile Dyeing and Printing Ministry of EducationWuhan 430073China

As a novel wastewater treatment strategy,the intimate coupling of photocatalysis and biodegradation(ICPB)has been attracted attention,which is ascribed to its combination of the advantages of photocatalytic reactions and biological treatment.The selection of carriers is important since it affects the stability of the system and the removal efficiency of pollutants.In this study,a novel ICPB system was successfully constructed by loading photocatalytic materials(i.e.,TiO_(2),N-TiO_(2),and Ag-TiO_(2))and microbes onto non-woven cotton fabric.The photocatalysts were characterized by scanning electron microscope-energy dispersive spectrometer(SEM-EDS),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).This system exhibited good performance in degrading tetracycline(TC)in water.The results showed that Ag-TiO_(2)-ICPB had the maximum removal efficiency of tetracycline(94.7%)in 5 h,which was 16.5%higher than the photocatalysis alone.After five cycles,82.9%of tetracycline could be still degraded through Ag-TiO_(2)-ICPB.SEM spectrum showed microbes on the material changed little before and after the reactions.This result implied the materials were stable,and then beneficial for degrading of pollutants continuously.The intermediates were detected through ultraperformance liquid chromatography-mass spectrometer(UPLC-MS)and the plausible degradation pathways were proposed.Electron paramagnetic resonance(EPR)analysis showed·OH and O_(2)·-were the main reactive oxygen species for TC degradation.In conclusion,the ICPB system with non-woven cotton fabric as a carrier has certain application prospects for antibiotic-containing wastewater.

关键词： Photocatalysis Biological treatment ICPB Non-woven cotton fabric Tetracycline removal

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