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Defect-induced deposition of manganese oxides on hierarchical carbon nanocages for high-performance lithium-oxygen batteries

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Nano Research 2022年第5期15卷 4132-4136页

作者： Baoxing Wang Chenxia Liu Lijun Yang Qiang Wu Xizhang Wang Zheng Hu Key Laboratory of Mesoscopic Chemistry of MOE and Jiangsu Provincial Laboratory for Nanotechnology School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

The cathode of lithium-oxygen(Li-O_(2))batteries should have large space for high Li_(2)O_(2) uptake and superior electrocatalytic activity to oxygen evolution/reduction for long lifespan.Herein,a high-performance MnO_(x)/hCNC cathode was constructed by the defect-induced deposition of manganese oxide(MnOx)nanoparticles on hierarchical carbon nanocages(hCNC).The corresponding Li-O2 battery(MnOx/hCNC@Li-O_(2))exhibited excellent electrocatalytic activity with the low overpotential of 0.73-0.99 V in the current density range of 0.1-1.0 A·g^(-1).The full discharge capacity and cycling life of MnO_(x)/hCNC@Li-O_(2) were increased by~86.7%and~91%,respectively,compared with the hCNC@Li-O_(2) counterpart.The superior performance of MnO_(x)/hCNC cathode was ascribed to(i)the highly dispersed MnO_(x) nanoparticles for boosting the reversibility of oxygen evolution/reduction reactions,(ii)the interconnecting pore structure for increasing Li_(2)O_(2) accommodation and facilitating charge/mass transfer,and(iii)the concealed surface defects of hCNC for suppressing side reactions.This study demonstrated an effective strategy to improve the performance of Li-O_(2) batteries by constructing cathodes with highly dispersed catalytic sites and hierarchical porous structure.

关键词： Li-O_(2) batteries hierarchical carbon nanocages manganese oxide electrocatalysis defect-induced deposition

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Advanced Ni-Nx-C single-site catalysts for CO2 electroreduction to CO based on hierarchical carbon nanocages and S-doping

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Nano Research 2020年第10期13卷 2777-2783页

作者： Yiqun Chen Yuejian Yao Yujian Xia Kun Mao Gongao Tang Qiang Wu Lijun Yang Xizhang Wang Xuhui Sun Zheng Hu Key Laboratory of Mesoscopic Chemistry of MOE and Jiangsu Provincial Lab for Nanotechnology School of Chemistry and Chemical Engineering Nanjing UniversityNanjing 210023China Soochow University-Western University Centre for Synchrotron Radiation ResearchInstitute of Functional Nano and Soft Material(FUNSOM)Soochow UniversitySuzhou 215123China

Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.

关键词： CO2 electroreduction single-site catalysts nickel-nitrogen-carbon S-doping hierarchical carbon nanocages

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增大分级结构碳纳米笼的离子传输微孔通道获得超高的能量密度和功率密度

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Science China Materials 2021年第9期64卷 2173-2181页

作者：赵进范豪李国昌吴强杨立军马延文王喜章胡征 Key Laboratory of Mesoscopic Chemistry of MOE and Jiangsu Provincial Lab for Nanotechnology School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China Jiangsu Key Lab for Organic Electronics and Information Displays&Institute of Advanced Materials Nanjing University of Posts and TelecommunicationsNanjing 210023China

提升超级电容器能量密度而不牺牲其高功率密度是能源存储领域的不懈追求.离子液体电解液具有大的工作电压窗口,以其为电解液可提升超级电容器能量密度.但离子液体离子尺寸大、离子电导率低且粘度高,通常会导致超级电容器功率密度的减小... 详细信息

提升超级电容器能量密度而不牺牲其高功率密度是能源存储领域的不懈追求.离子液体电解液具有大的工作电压窗口,以其为电解液可提升超级电容器能量密度.但离子液体离子尺寸大、离子电导率低且粘度高,通常会导致超级电容器功率密度的减小.本文主要通过增大分级结构碳纳米笼(hCNC)电极材料的离子传输微孔通道,实现了在EMIMBF4离子液体电解液中超级电容器能量密度和功率密度的协同提升.通过Boudouard反应,在保持hCNC独特分级结构的前提下调节了贯穿碳纳米笼壁的微孔尺寸,同时,在优化的活化温度下hCNC的比表面积、孔体积和导电性均得以提升.这种独特的调节促进了大尺寸离子的传输,有效降低了等效串联电阻,从而显著提升了超级电容器的性能.优化的样品在功率密度为1.8 kW kg^(-1)时的能量密度高达153.8 W h kg^(-1),在超高功率密度480.1 kW kg^(-1)时能量密度仍能保持54.0 W h kg^(-1).本研究展示了一种通过精细调控材料微孔及相关性质开发先进电极材料的有效方法.

关键词： supercapacitors ultrahigh energy and power densities hierarchical carbon nanocages micropore enlarging ionic liquid electrolyte

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