将醋酸镍和葡萄糖溶于水中,与氧化石墨烯(GO)水悬浮液均匀混合,在180℃下水热处理24 h,再在Ar中700℃下炭化3 h,然后在空气中300℃下煅烧3 h得到三维Ni/NiO@C/GN。结果表明,水热处理过程中葡萄糖衍生的炭层将Ni(OH)2完全包裹,并在炭化...将醋酸镍和葡萄糖溶于水中,与氧化石墨烯(GO)水悬浮液均匀混合,在180℃下水热处理24 h,再在Ar中700℃下炭化3 h,然后在空气中300℃下煅烧3 h得到三维Ni/NiO@C/GN。结果表明,水热处理过程中葡萄糖衍生的炭层将Ni(OH)2完全包裹,并在炭化过程中转化为金属Ni,部分金属Ni在空气中煅烧中被氧化为NiO。当作为锂离子电池的负极材料时,其初始容量为711.6 mA h g^(-1),300次循环后增加到772.1 mA h g^(-1)。作为对比,没有添加GO的材料的初始容量较低,仅为584.7 mA h g^(-1),300次循环后下降到148.8 mA h g^(-1)。这些结果表明炭层可以抑制Ni/NiO纳米颗粒的团聚,有效缓解锂化过程中的体积膨胀,抑制循环过程中的电极开裂。GO的加入可形成丰富的导电网络,提高导电性。较大的比表面积可增加活性位点,有利于电解液快速浸润电极材料。这些因素显著改善了Ni/NiO@C/GN负极的电化学性能。展开更多
Yolk–shell urchin-like porous Co_(3)O_(4)/NiO@C microspheres were successfully synthesized via a facile solvothermal method and annealing treatment under an argon atmosphere.High reversible specific capacity,long cyc...Yolk–shell urchin-like porous Co_(3)O_(4)/NiO@C microspheres were successfully synthesized via a facile solvothermal method and annealing treatment under an argon atmosphere.High reversible specific capacity,long cycling stability,and excellent rate capability were achieved for the material due to its specific yolk–shell urchin-like porous structure and coated carbon layers.The pores distributed on the yolk and shell,as well as the gap between the yolk and shell,provide numerous pathways for the penetration of electrolyte,and enhance the reversible specific capacity(the initial discharge specific capacity was as high as 1405.7 mA h g^(-1) at 0.1 C).Meanwhile,the stress and volume expansion could be greatly released and relieved through the pores,and long cycling stability was achieved(a high reversible specific capacity of 502.7 mA h g^(-1) was maintained after 1000 cycles at 5 C).The coated carbon layers greatly enhance the conductivity of the yolk–shell urchin-like porous Co_(3)O_(4)/NiO microspheres,accelerate the transmission of electrons,and improve their rate performance(a reversible specific capacity of 397.5 mA h g^(-1) was achieved when the current density was increased to 10 C).展开更多
Available online Further oxidation of NH3produced via photocatalytic N_(2)fixation represents a promising strategy to enhance the economic value of N_(2)fixation.This work employs first-principles density functional t...Available online Further oxidation of NH3produced via photocatalytic N_(2)fixation represents a promising strategy to enhance the economic value of N_(2)fixation.This work employs first-principles density functional theory(DFT)calculations to demonstrate that incorporating Co into Ni O improves both N_(2)adsorption and activation as well as M-N electron exchange intensity.Guided by these predictions,a novel Co single-atom photocatalyst supported by nanoconfined Ni O@C nanosheets was synthesized using a direct metal atomization method,achieving high HNO_(3)production(60.54%).NH_(4)^(+)and NO_(3)^(-)production rates during N_(2)photofixation reached 67.97μmol g_(cat)^(-1)h^(-1)and 104.28μmol g_(cat)^(-1)h^(-1),respectively.The overall N_(2)→NH_(3)→HNO_(3)photofixation pathway was validated through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and^(15)N isotopic labeling.Mechanistic studies reveal that Co single-atom introduction serves as an electron trap,enhancing photogenerated electron accumulation with a five-fold increase in carrier density compared to Ni O@C,as observed via in-situ X-ray photoelectron spectroscopy(XPS).This synergistic effect between electron traps and N2adsorption/activation sites at Co single-atom centers supports rapid N_(2)reduction kinetics.Additionally,nanoconfined ink-bottle pores in the carbon layer impede NH_(3)desorption,further boosting NO_(3)-production.This work offers a comprehensive approach to optimizing N_(2)photofixation through electron regulation and surface reaction kinetics.展开更多
采用简单的静电纺丝方法制备了Ni/NiO/C负极材料。XRD证明该材料主要由NiO、Ni和无定形碳组成。SEM证明Ni/NiO/C的形貌呈纤维状,纤维的直径为400~500 nm。以Ni/NiO/C为锂电的负极材料,在100 mA g^(-1)的电流密度下,首次充电比容量可达到...采用简单的静电纺丝方法制备了Ni/NiO/C负极材料。XRD证明该材料主要由NiO、Ni和无定形碳组成。SEM证明Ni/NiO/C的形貌呈纤维状,纤维的直径为400~500 nm。以Ni/NiO/C为锂电的负极材料,在100 mA g^(-1)的电流密度下,首次充电比容量可达到586.5 mAh g^(-1),循环50圈后的充电比容量仍可达到453.2 mAh g^(-1),容量保持率为77.27%。展开更多
The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic(EM)wave absorption performance.Herein,the Ni/NiO@C hybrid composites with tunable Ni propor...The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic(EM)wave absorption performance.Herein,the Ni/NiO@C hybrid composites with tunable Ni proportion were successfully synthesized through a two-step process.With the assistance of X-ray diffraction with refinement treatment,the specific proportion of Ni of as-obtained hybrid composites could be obtained.Employing controlling calcination time to adjust the Ni content of Ni/NiO@C hybrid composites,it has been found that the composite carbonized at 500℃exhibited remarkable EM wave absorption with the minimum reflection loss(RLmin)of-49.1 dB at 4.9 mm and the widest effective absorption bandwidth(EABmax)of 4.56 GHz at 2.1 mm.Moreover,by adjusting the Ni source,the optimal EM wave absorption performance could be achieved.Results illustrated that the N3PC with the Ni proportion of 13.17%showed the RLm inas low as-51.1 dB at 2.4 mm and the EABmax was 5.12 GHz at 2.7 mm.It is worth noting that this work demonstrates the relevance of the composition and EM wave absorption performance of hybrid composites,which offers a feasible reference for the absorption mechanism of absorber.展开更多
以硝酸镍为镍源,通过水热法制成NiO-C载体,随后利用L-抗坏血酸和氢气将铂离子镶嵌入载体中,制备出Pt和NiO共存的Pt@NiO-C催化剂,并对其全解水性能进行测试。首先运用XRD、SEM、XPS等测试手段,对材料组成与结构进行了表征。结果表明,半导...以硝酸镍为镍源,通过水热法制成NiO-C载体,随后利用L-抗坏血酸和氢气将铂离子镶嵌入载体中,制备出Pt和NiO共存的Pt@NiO-C催化剂,并对其全解水性能进行测试。首先运用XRD、SEM、XPS等测试手段,对材料组成与结构进行了表征。结果表明,半导体NiO不仅可以作为析氢贵金属载体,同时也可以为析氧提供活性点位。电化学测试结果显示,在浓度为0.5 mol/L的硫酸溶液中,Pt@NiO-C材料的析氢起始电位仅为25 mV(VS.RHE),塔菲尔斜率为31 m V·dec^(-1),经过20个小时的连续工作依旧能保持稳定的催化性能,析氧性能优于商用铂碳(20%),为质子交换膜制氢技术的发展提供一种新的思路。展开更多
文摘将醋酸镍和葡萄糖溶于水中,与氧化石墨烯(GO)水悬浮液均匀混合,在180℃下水热处理24 h,再在Ar中700℃下炭化3 h,然后在空气中300℃下煅烧3 h得到三维Ni/NiO@C/GN。结果表明,水热处理过程中葡萄糖衍生的炭层将Ni(OH)2完全包裹,并在炭化过程中转化为金属Ni,部分金属Ni在空气中煅烧中被氧化为NiO。当作为锂离子电池的负极材料时,其初始容量为711.6 mA h g^(-1),300次循环后增加到772.1 mA h g^(-1)。作为对比,没有添加GO的材料的初始容量较低,仅为584.7 mA h g^(-1),300次循环后下降到148.8 mA h g^(-1)。这些结果表明炭层可以抑制Ni/NiO纳米颗粒的团聚,有效缓解锂化过程中的体积膨胀,抑制循环过程中的电极开裂。GO的加入可形成丰富的导电网络,提高导电性。较大的比表面积可增加活性位点,有利于电解液快速浸润电极材料。这些因素显著改善了Ni/NiO@C/GN负极的电化学性能。
基金supported by the National Natural Science Foundation of China(51725101,11727807,51672050,61790581)the Ministry of Science and Technology of China(973 Project No.2018YFA0209102)the science and technology research project of Jiangxi Provincial Department of Education(GJJ200338).
文摘Yolk–shell urchin-like porous Co_(3)O_(4)/NiO@C microspheres were successfully synthesized via a facile solvothermal method and annealing treatment under an argon atmosphere.High reversible specific capacity,long cycling stability,and excellent rate capability were achieved for the material due to its specific yolk–shell urchin-like porous structure and coated carbon layers.The pores distributed on the yolk and shell,as well as the gap between the yolk and shell,provide numerous pathways for the penetration of electrolyte,and enhance the reversible specific capacity(the initial discharge specific capacity was as high as 1405.7 mA h g^(-1) at 0.1 C).Meanwhile,the stress and volume expansion could be greatly released and relieved through the pores,and long cycling stability was achieved(a high reversible specific capacity of 502.7 mA h g^(-1) was maintained after 1000 cycles at 5 C).The coated carbon layers greatly enhance the conductivity of the yolk–shell urchin-like porous Co_(3)O_(4)/NiO microspheres,accelerate the transmission of electrons,and improve their rate performance(a reversible specific capacity of 397.5 mA h g^(-1) was achieved when the current density was increased to 10 C).
基金supported by the National Natural Science Foundation of China(No.62004143)the Key Research and Development Program of Gansu Province-Industrial Project under Grant(No.25YFGA058)+4 种基金the Key Talent Project Foundation of Gansu Province(No.2025RCXM066)the Gansu Provincial Department of Education:Industrial Support Plan Project(No.2025CYZC-005)the Key R&D Program of Hubei Province(No.2022BAA084)the Science and Technology Project of Lanzhou(No.2024-3-42)the Fundamental Research Funds for the Central Universities(No.331920240059)。
文摘Available online Further oxidation of NH3produced via photocatalytic N_(2)fixation represents a promising strategy to enhance the economic value of N_(2)fixation.This work employs first-principles density functional theory(DFT)calculations to demonstrate that incorporating Co into Ni O improves both N_(2)adsorption and activation as well as M-N electron exchange intensity.Guided by these predictions,a novel Co single-atom photocatalyst supported by nanoconfined Ni O@C nanosheets was synthesized using a direct metal atomization method,achieving high HNO_(3)production(60.54%).NH_(4)^(+)and NO_(3)^(-)production rates during N_(2)photofixation reached 67.97μmol g_(cat)^(-1)h^(-1)and 104.28μmol g_(cat)^(-1)h^(-1),respectively.The overall N_(2)→NH_(3)→HNO_(3)photofixation pathway was validated through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and^(15)N isotopic labeling.Mechanistic studies reveal that Co single-atom introduction serves as an electron trap,enhancing photogenerated electron accumulation with a five-fold increase in carrier density compared to Ni O@C,as observed via in-situ X-ray photoelectron spectroscopy(XPS).This synergistic effect between electron traps and N2adsorption/activation sites at Co single-atom centers supports rapid N_(2)reduction kinetics.Additionally,nanoconfined ink-bottle pores in the carbon layer impede NH_(3)desorption,further boosting NO_(3)-production.This work offers a comprehensive approach to optimizing N_(2)photofixation through electron regulation and surface reaction kinetics.
文摘采用简单的静电纺丝方法制备了Ni/NiO/C负极材料。XRD证明该材料主要由NiO、Ni和无定形碳组成。SEM证明Ni/NiO/C的形貌呈纤维状,纤维的直径为400~500 nm。以Ni/NiO/C为锂电的负极材料,在100 mA g^(-1)的电流密度下,首次充电比容量可达到586.5 mAh g^(-1),循环50圈后的充电比容量仍可达到453.2 mAh g^(-1),容量保持率为77.27%。
基金financially supported by the National Natural Science Foundation of China(Nos.51407134,51801001 and 51801108)Natural Science Foundation of Shandong Province(No.ZR2019YQ24)+5 种基金China Postdoctoral Science Foundation(No.2016M590619,No.2016M601878)Provincial Key Research and Development Program of Shaanxi(No.2019GY-197)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)the support from The Thousand Talents PlanThe World-Class University and DisciplineThe Taishan Scholar’s Advantageous and Distinctive Discipline Program of Shandong ProvinceThe World-Class Discipline Program of Shandong Province。
文摘The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic(EM)wave absorption performance.Herein,the Ni/NiO@C hybrid composites with tunable Ni proportion were successfully synthesized through a two-step process.With the assistance of X-ray diffraction with refinement treatment,the specific proportion of Ni of as-obtained hybrid composites could be obtained.Employing controlling calcination time to adjust the Ni content of Ni/NiO@C hybrid composites,it has been found that the composite carbonized at 500℃exhibited remarkable EM wave absorption with the minimum reflection loss(RLmin)of-49.1 dB at 4.9 mm and the widest effective absorption bandwidth(EABmax)of 4.56 GHz at 2.1 mm.Moreover,by adjusting the Ni source,the optimal EM wave absorption performance could be achieved.Results illustrated that the N3PC with the Ni proportion of 13.17%showed the RLm inas low as-51.1 dB at 2.4 mm and the EABmax was 5.12 GHz at 2.7 mm.It is worth noting that this work demonstrates the relevance of the composition and EM wave absorption performance of hybrid composites,which offers a feasible reference for the absorption mechanism of absorber.
基金Xinjiang Uygur Autonomous Region University Scientific Research Project(XJEDU2012I05)National Natural Science Foundation of China(21162027,21063013)
文摘将核壳的聚吡咯基的碳@碳纳米管(C@CNT)与纳米片组装的氧化镍(Ni O)微球结合,制备了一种多孔的锂离子电池负极材料(Ni O/C@CNT),该材料(Ni O/C@CNT)与纯的Ni O和Ni O/CNT相比,其容量值和循环稳定性能明显提高。在50 m A·g-1的电流密度下,经过20次循环后,其可逆容量达到573 m A·g-1,容量保持率为68.6%。这些性能的提高是由于核壳结构的C@CNT的导电缓冲性引起的。C@CNT具有诸如多孔结构、大比表面积、高电化学活性、高电子导电性和良好的浸润性等许多优点,这些优点有利于避免电极材料显著的体积变化,因此在锂嵌入和脱出过程中可减少电极容量衰减并提高传质速率。
基金National Natural Science Foundation of China(51202112,51402150)Natural Science Foundation of Jiangsu Province(BK20130737)Scientific Research Fund of Nanjing Institute of Technology(YKJ201206,YKJ201209,ZKJ201302,CKJA201303)
文摘以硝酸镍为镍源,通过水热法制成NiO-C载体,随后利用L-抗坏血酸和氢气将铂离子镶嵌入载体中,制备出Pt和NiO共存的Pt@NiO-C催化剂,并对其全解水性能进行测试。首先运用XRD、SEM、XPS等测试手段,对材料组成与结构进行了表征。结果表明,半导体NiO不仅可以作为析氢贵金属载体,同时也可以为析氧提供活性点位。电化学测试结果显示,在浓度为0.5 mol/L的硫酸溶液中,Pt@NiO-C材料的析氢起始电位仅为25 mV(VS.RHE),塔菲尔斜率为31 m V·dec^(-1),经过20个小时的连续工作依旧能保持稳定的催化性能,析氧性能优于商用铂碳(20%),为质子交换膜制氢技术的发展提供一种新的思路。
