The effects of NOx(in a ratio of NO∶NO2=9∶1) and SO2in cathode streamonthe performance of a single proton ex-change membrane fuel cell(PEMFC) were investigated.NOxwith concentrations of 1×10-3%(in volume,the sa...The effects of NOx(in a ratio of NO∶NO2=9∶1) and SO2in cathode streamonthe performance of a single proton ex-change membrane fuel cell(PEMFC) were investigated.NOxwith concentrations of 1×10-3%(in volume,the same as fol-lows),1.4×10-2%and 1×10-3%could cause significant detri mental effects on the cell performance.However,nearly com-plete recovery of the cell performance could be observed after NOxwas shut off and purged with clean air.The electrochemicalmeasurements suggested that thei mpacts of NOxresulted mainlyfromthe superposition of the oxygen reduction reaction(ORR),NOand HNO2oxidation reactions,and the increased cathodic i mpedance.Trace SO2with concentrations of 5×10-6%,5×10-3%,2×10-4%and 3.2×10-4%influenced the cell muchseverer,which could be attributed toits strong adsorption onthesurface of Pt atoms.The cell performance could not be completely recovered after purged with clean air and cyclic voltammetry(CV) tests,due to the changes of electrochemical i mpedance spectroscopy(EIS) and electrochemical active surface(EAS) causedby surface state change after SO2exposure.展开更多
The nitrogen and sulfur co-doped carbon dots(N, S-CDs) with increased luminescence were synthesized by a hydrothermal process in one green pot by using glucose, and a new sulfur-doping source of sodium sulfite was dev...The nitrogen and sulfur co-doped carbon dots(N, S-CDs) with increased luminescence were synthesized by a hydrothermal process in one green pot by using glucose, and a new sulfur-doping source of sodium sulfite was developed.The synergistic effect of the N and S groups was well discussed through the structure analysis of Fourier transform infrared spectra and x-ray photoelectron spectra. The surface states of N, S-CDs embody more complicated functional groups, and S element exists as –SSO3, –C–SO3, and SO-42groups due to the introduction of sodium sulfite. The sulfur-containing groups passivate the surface of the CDs, and the relatively high sulfur groups may reduce the non-radiation centers. The fluorescence is affected by the hydroxyl group of the solvent. The quenching of Fe3+ ion to fluorescence and the sensitivity of fluorescence to p H were also investigated.展开更多
The notorious shuttle effect has long been obstructing lithium-sulfur(Li-S) batteries from yielding the expected high energy density and long lifespan.Herein,we develop a multifunctional polysulfide barrier reinforced...The notorious shuttle effect has long been obstructing lithium-sulfur(Li-S) batteries from yielding the expected high energy density and long lifespan.Herein,we develop a multifunctional polysulfide barrier reinforced by the graphitic carbon nitride/carbon nanotube(g-C_3 N_4/CNT) composite toward inhibited shuttling behavior and improved battery performance.The obtained g-C_3 N_4 delivers a unique spongelike architecture with massive ion transfer pathways and fully exposed active interfaces,while the abundant C-N heteroatomic structures impose strong chemical immobilization toward lithium polysulfides.Combined with the highly conductive agent,the g-C_3 N_4/CNT reinforced separator is endowed with great capability of confining and reutilizing the active sulfur within the cathode,thus contributing to an efficient and stable sulfur electrochemistry.Benefiting from these synergistic attributes,Li-S cells based on g-C_3 N_4/CNT separator exhibit an excellent cyclability with a minimum decay rate of 0.03% per cycle over 500 cycles and decent rate capability up to 2 C.Moreover,a high areal capacity of 7.69 mAh cm^(-2)can be achieved under a raised sulfur loading up to 10.1 mg cm^(-2).demonstrating a facile and efficient pathway toward superior Li-S batteries.展开更多
Shuttle effect,poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes.Currently,rational structure designing of carbon-based sulfur hosts is the most...Shuttle effect,poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes.Currently,rational structure designing of carbon-based sulfur hosts is the most effective strategy to address the above issues.However,the preparation process of carbon-based sulfur hosts is usually complex and costly.Therefore,it is necessary to develop an efficient and cost-effective method to fabricate carbon hosts for high-performance sulfur cathodes.Herein,we reported the fabrication of a bio-derived nitrogen doped porous carbon materials(BNPC)via a molten-salt method for high performance sulfur cathodes.The long-range-ordered honeycomb structure of BNPC is favorable for the trapping of polysulfide(PS)species and accommodates the volumetric variation of sulfur during cycling,while the high graphitization degree of BNPC favors the redox kinetics of sulfur cathodes.Moreover,the nitrogen doping content not only enhances the electrical conductivity of BNPC,but also provides ample anchoring sites for the immobilization of PS,which plays a key role in suppressing the shuttle effect.As a result,the S@BNPC cathode exhibits a high initial specific capacity of 1189.4 mA·h/g at 0.2C.After 300 cycles,S@BNPC still maintains a capacity of 703.2 mA·h/g which corresponds to a fading rate of 0.13%per cycle after the second cycle.This work offers vast opportunities for the large-scale application of high performance carbon-based sulfur hosts.展开更多
水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80%WHC)进行室内微宇...水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80%WHC)进行室内微宇宙培养试验,通过添加乙炔抑制剂抑制自养硝化途径,研究水氮耦合对设施土壤自养和异养硝化速率及参与自养硝化的氨氧化微生物的影响,分析氨氧化微生物氨氧化古细菌(AOA)和氨氧化细菌(AOB)对自养硝化作用的贡献。结果表明,水氮耦合下,不同硝化途径NH_(4)^(+)-N、NO_(3)^(-)-N含量以及参与自养硝化的AOA amo A和AOB amo A基因拷贝数均有显著差异。无乙炔培养7 d后,NO_(3)^(-)-N含量显著增加,而NH_(4)^(+)-N含量显著降低,AOA amo A和AOB amo A的基因丰度显著增加。添加乙炔后,NO_(3)^(-)-N、NH_(4)^(+)-N含量基本保持恒定,AOA amo A和AOB amo A基因丰度显著减少。水氮耦合显著影响自养和异养硝化速率,冗余分析(RDA)表明,NH_(4)^(+)-N含量、AOB amo A、NO_(3)^(-)-N-C_(2)H_(2)、AOA amo A可分别解释自养和异养硝化速率变异的68.9%、34.9%、32.8%和24.4%。设施土壤存在自养硝化和异养硝化两种途径,60%~80%WHC各施氮处理均以自养硝化为主,占总硝化速率的65%~86%;仅40%WHC下,氮纯养分量300和525 kg·hm^(-2)处理以异养硝化为主,占总硝化速率的61%~77%。AOB和AOA共同驱动自养硝化,且AOB贡献更大。展开更多
试验采用裂裂区设计,小麦品种（烟农19和汶农6号）为主区,施氮（N）量为裂区,设0（N0）、120（N120）、240（N240）kg hm-2三个施N水平,施硫（S）量为裂裂区,设0（S0）、20（S20）、40（S40）、60（S60）kg hm-2四个施S水平。结果表明,...试验采用裂裂区设计,小麦品种（烟农19和汶农6号）为主区,施氮（N）量为裂区,设0（N0）、120（N120）、240（N240）kg hm-2三个施N水平,施硫（S）量为裂裂区,设0（S0）、20（S20）、40（S40）、60（S60）kg hm-2四个施S水平。结果表明,汶农6号开花后旗叶超氧化物歧化酶（SOD）活性、旗叶净光合速率、产量和氮素利用效率均高于烟农19。在一定施氮水平下适量施硫显著提高烟农19和汶农6号小麦开花后旗叶SOD活性和可溶性蛋白质含量,提高旗叶净光合速率和开花后干物质积累量,增加植株地上部氮素积累量和籽粒产量;当施氮水平为120 kg hm-2施硫量超过40 kg hm-2和施氮240 kg hm-2施硫量超过20 kg hm-2时,汶农6号植株地上部氮素积累量仍继续增加,但旗叶抗氧化能力和光合同化能力均无明显提高,籽粒产量不再增加,烟农19号旗叶SOD活性、可溶性蛋白质含量和光合速率均降低,植株地上部氮素积累量和籽粒产量均减少。在同一施氮水平下,两小麦品种氮素利用效率总体表现为随施硫量增加而降低的趋势。在土壤有效硫为38.9~42.1 mg kg-1的条件下,适量施用氮肥和硫肥有利于延缓小麦花后旗叶衰老,提高光合同化能力,增加籽粒产量,但不同品种小麦对氮肥和硫肥施用量的响应不同,氮素利用效率较高的品种在较高的氮硫供给水平下仍有较好的光合同化和产量表现,而氮素利用效率相对低的品种对高氮高硫的适应性较差,后期易早衰,影响产量和氮素利用效率。展开更多
文摘The effects of NOx(in a ratio of NO∶NO2=9∶1) and SO2in cathode streamonthe performance of a single proton ex-change membrane fuel cell(PEMFC) were investigated.NOxwith concentrations of 1×10-3%(in volume,the same as fol-lows),1.4×10-2%and 1×10-3%could cause significant detri mental effects on the cell performance.However,nearly com-plete recovery of the cell performance could be observed after NOxwas shut off and purged with clean air.The electrochemicalmeasurements suggested that thei mpacts of NOxresulted mainlyfromthe superposition of the oxygen reduction reaction(ORR),NOand HNO2oxidation reactions,and the increased cathodic i mpedance.Trace SO2with concentrations of 5×10-6%,5×10-3%,2×10-4%and 3.2×10-4%influenced the cell muchseverer,which could be attributed toits strong adsorption onthesurface of Pt atoms.The cell performance could not be completely recovered after purged with clean air and cyclic voltammetry(CV) tests,due to the changes of electrochemical i mpedance spectroscopy(EIS) and electrochemical active surface(EAS) causedby surface state change after SO2exposure.
基金Project by the National Natural Science Foundation of China(Grant Nos.51571085,11805052,and 61705062)the Research Project for Basic and Forefront Technology of Henan Province,China(Grant No.162300410219)the Doctor Foundation of Henan Polytechnic University,China(Grant No.B2014049)
文摘The nitrogen and sulfur co-doped carbon dots(N, S-CDs) with increased luminescence were synthesized by a hydrothermal process in one green pot by using glucose, and a new sulfur-doping source of sodium sulfite was developed.The synergistic effect of the N and S groups was well discussed through the structure analysis of Fourier transform infrared spectra and x-ray photoelectron spectra. The surface states of N, S-CDs embody more complicated functional groups, and S element exists as –SSO3, –C–SO3, and SO-42groups due to the introduction of sodium sulfite. The sulfur-containing groups passivate the surface of the CDs, and the relatively high sulfur groups may reduce the non-radiation centers. The fluorescence is affected by the hydroxyl group of the solvent. The quenching of Fe3+ ion to fluorescence and the sensitivity of fluorescence to p H were also investigated.
基金supported by the National Natural Science Foundation of China (Nos. 21978110 and 51772126)the Natural Science Foundation of Beijing (No. L182062)+8 种基金the Organization Department of Beijing Talents Project (2018000021223ZK21)the Yue Qi Young Scholar Project of China University of Mining & Technology (Beijing) (No. 2017QN17)the Fundamental Research Funds for the Central Universities (No. 2014QJ02)the Jilin Province Science and Technology Department Program (Nos. 20200201187JC, 20190201309JC, and 20190101009JH)the ‘‘13th five-year” Science and Technology Project of Jilin Provincial Education Department (No. JJKH20200407KJ)the Jilin Province Development and Reform Commission Program (Nos. 2020C026-3 and 2019C042-1)the Jilin Province Fund for Talent Development Program (No. [2019] 874)the supports from Natural Sciences and Engineering Research Council of Canada (NSERC), the University of Waterloothe Waterloo Institute for Nanotechnology。
文摘The notorious shuttle effect has long been obstructing lithium-sulfur(Li-S) batteries from yielding the expected high energy density and long lifespan.Herein,we develop a multifunctional polysulfide barrier reinforced by the graphitic carbon nitride/carbon nanotube(g-C_3 N_4/CNT) composite toward inhibited shuttling behavior and improved battery performance.The obtained g-C_3 N_4 delivers a unique spongelike architecture with massive ion transfer pathways and fully exposed active interfaces,while the abundant C-N heteroatomic structures impose strong chemical immobilization toward lithium polysulfides.Combined with the highly conductive agent,the g-C_3 N_4/CNT reinforced separator is endowed with great capability of confining and reutilizing the active sulfur within the cathode,thus contributing to an efficient and stable sulfur electrochemistry.Benefiting from these synergistic attributes,Li-S cells based on g-C_3 N_4/CNT separator exhibit an excellent cyclability with a minimum decay rate of 0.03% per cycle over 500 cycles and decent rate capability up to 2 C.Moreover,a high areal capacity of 7.69 mAh cm^(-2)can be achieved under a raised sulfur loading up to 10.1 mg cm^(-2).demonstrating a facile and efficient pathway toward superior Li-S batteries.
基金Project(2018YFB0104300)supported by the National Key R&D Program of ChinaProject(51774150)supported by the National Natural Science Foundation of China
文摘Shuttle effect,poor conductivity and large volume expansion are the main factors that hinder the practical application of sulfur cathodes.Currently,rational structure designing of carbon-based sulfur hosts is the most effective strategy to address the above issues.However,the preparation process of carbon-based sulfur hosts is usually complex and costly.Therefore,it is necessary to develop an efficient and cost-effective method to fabricate carbon hosts for high-performance sulfur cathodes.Herein,we reported the fabrication of a bio-derived nitrogen doped porous carbon materials(BNPC)via a molten-salt method for high performance sulfur cathodes.The long-range-ordered honeycomb structure of BNPC is favorable for the trapping of polysulfide(PS)species and accommodates the volumetric variation of sulfur during cycling,while the high graphitization degree of BNPC favors the redox kinetics of sulfur cathodes.Moreover,the nitrogen doping content not only enhances the electrical conductivity of BNPC,but also provides ample anchoring sites for the immobilization of PS,which plays a key role in suppressing the shuttle effect.As a result,the S@BNPC cathode exhibits a high initial specific capacity of 1189.4 mA·h/g at 0.2C.After 300 cycles,S@BNPC still maintains a capacity of 703.2 mA·h/g which corresponds to a fading rate of 0.13%per cycle after the second cycle.This work offers vast opportunities for the large-scale application of high performance carbon-based sulfur hosts.
文摘水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80%WHC)进行室内微宇宙培养试验,通过添加乙炔抑制剂抑制自养硝化途径,研究水氮耦合对设施土壤自养和异养硝化速率及参与自养硝化的氨氧化微生物的影响,分析氨氧化微生物氨氧化古细菌(AOA)和氨氧化细菌(AOB)对自养硝化作用的贡献。结果表明,水氮耦合下,不同硝化途径NH_(4)^(+)-N、NO_(3)^(-)-N含量以及参与自养硝化的AOA amo A和AOB amo A基因拷贝数均有显著差异。无乙炔培养7 d后,NO_(3)^(-)-N含量显著增加,而NH_(4)^(+)-N含量显著降低,AOA amo A和AOB amo A的基因丰度显著增加。添加乙炔后,NO_(3)^(-)-N、NH_(4)^(+)-N含量基本保持恒定,AOA amo A和AOB amo A基因丰度显著减少。水氮耦合显著影响自养和异养硝化速率,冗余分析(RDA)表明,NH_(4)^(+)-N含量、AOB amo A、NO_(3)^(-)-N-C_(2)H_(2)、AOA amo A可分别解释自养和异养硝化速率变异的68.9%、34.9%、32.8%和24.4%。设施土壤存在自养硝化和异养硝化两种途径,60%~80%WHC各施氮处理均以自养硝化为主,占总硝化速率的65%~86%;仅40%WHC下,氮纯养分量300和525 kg·hm^(-2)处理以异养硝化为主,占总硝化速率的61%~77%。AOB和AOA共同驱动自养硝化,且AOB贡献更大。
文摘试验采用裂裂区设计,小麦品种（烟农19和汶农6号）为主区,施氮（N）量为裂区,设0（N0）、120（N120）、240（N240）kg hm-2三个施N水平,施硫（S）量为裂裂区,设0（S0）、20（S20）、40（S40）、60（S60）kg hm-2四个施S水平。结果表明,汶农6号开花后旗叶超氧化物歧化酶（SOD）活性、旗叶净光合速率、产量和氮素利用效率均高于烟农19。在一定施氮水平下适量施硫显著提高烟农19和汶农6号小麦开花后旗叶SOD活性和可溶性蛋白质含量,提高旗叶净光合速率和开花后干物质积累量,增加植株地上部氮素积累量和籽粒产量;当施氮水平为120 kg hm-2施硫量超过40 kg hm-2和施氮240 kg hm-2施硫量超过20 kg hm-2时,汶农6号植株地上部氮素积累量仍继续增加,但旗叶抗氧化能力和光合同化能力均无明显提高,籽粒产量不再增加,烟农19号旗叶SOD活性、可溶性蛋白质含量和光合速率均降低,植株地上部氮素积累量和籽粒产量均减少。在同一施氮水平下,两小麦品种氮素利用效率总体表现为随施硫量增加而降低的趋势。在土壤有效硫为38.9~42.1 mg kg-1的条件下,适量施用氮肥和硫肥有利于延缓小麦花后旗叶衰老,提高光合同化能力,增加籽粒产量,但不同品种小麦对氮肥和硫肥施用量的响应不同,氮素利用效率较高的品种在较高的氮硫供给水平下仍有较好的光合同化和产量表现,而氮素利用效率相对低的品种对高氮高硫的适应性较差,后期易早衰,影响产量和氮素利用效率。
