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Enhanced sulfide chemisorption by conductive AI-doped ZnO decorated carbon nanoflakes for advanced Li-S batteries

Nano Research 2018年第1期11卷 477-489页

作者： Yangbo Kong Jianmin Luo Chengbin Jin Huadong Yuan Ouwei Sheng Liyuan Zhang Cong Fang Wenkui Zhang Hui Huang Yang Xia Chu Liang Jun Zhang Yongping Gan Xinyong Tao College of Materials Science and Engineering Zhejiang University of Technology Hangzhou 310014 China

Lithium-sulfur batteries have attracted significant attention recently due to their high theoretical capacity, energy density and cost effectiveness. However, sulfur cathodes suffer from issues such as shuttle effects, uncontrollable deposition of lithium sulfides species, and volume expansion of sulfur, which result in rapid capacity fading and low Coulombic efficiency. In recent years, metal-oxide nanostructures have been widely used in Li-S batteries, owing to their effective inhibition of the shuttle effect and controlled deposition of lithium sulfide. However, the nonconductive metal-oxides used in Li-S batteries suffer from extra diffusion process, which slows down the electrochemical reaction kinetics. Herein, we report the synthesis of carbon nanoflakes decorated with conductive aluminium-doped zinc oxide （AZO@C） nanoparticles, through a facile biotem- plating method using kapok fibers as both the template and carbon source. A sulfur cathode based on the AZO@C nanocomposites shows better electrochemical performance than those of cathodes based on ZnO and A1203 with poor conductivity, with a stable capacity of 927 mAh.g-1 at 0.1C （1C = 1,675 mA.g-1） after 100 cycles. A reversible capacity of 544 mAh.g-1 after 300 cycles was obtained even after increasing the current density to 0.5C, with a 0.039% capacity decay per cycle under a sulfur loading of 3.3 mg-cm-2. Moreover, a capacity of 466 mAh.g-1 after 100 cycles at 0.5C could still be obtained when the sulfur loading was increased to 6.96 ***-2. The excellent electrochemical performance of the AZO@C/S composite can be attributed to its high conductivity of the polar AZO host, which suppresses the shuttle effect while simultaneously improving the redox kinetics in the reciprocal transformation of lithium sulfide species.

关键词： lithium-sulfur battery aluminium-doped zincoxide conductive nanostructure biotemplate carbon nanoflakes

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Facile Synthesis of N-Doped Graphene-Like carbon nanoflakes as Efficient and Stable Electrocatalysts for the Oxygen Reduction Reaction

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Nano-Micro Letters 2018年第2期10卷 114-125页

作者： Daguo Gu Yao Zhou Ruguang Ma Fangfang Wang Qian Liu Jiacheng Wang School of Materials Engineering Yancheng Institute of Technology State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of Sciences Shanghai Institute of Materials Genome

A series of N-doped carbon materials(NCs)were synthesized by using biomass citric acid and dicyandiamide as renewable raw materials via a facile onestep pyrolysis method. The characterization of microstructural features shows that the NCs samples are composed of few-layered graphene-like nanoflakes with controlled in situ N doping, which is attributed to the confined pyrolysis of citric acid within the interlayers of the dicyandiamide-derived g-C_3N_4 with high nitrogen contents. Evidently, the pore volumes of the NCs increased with the increasing content of dicyandiamide in the precursor. Among these samples, the NCs nanoflakes prepared with the citric acid/dicyandiamide mass ratio of 1:6, NC-6,show the highest N content of ~6.2 at%, in which pyridinic and graphitic N groups are predominant. Compared to the commercial Pt/C catalyst, the as-prepared NC-6 exhibits a small negative shift of ~66 mV at the half-wave potential, demonstrating excellent electrocatalytic activity in the oxygen reduction reaction. Moreover, NC-6 also shows better long-term stability and resistance to methanol crossover compared to Pt/C. The efficient and stable performance are attributed to the graphene-like microstructure and high content of pyridinic and graphitic doped nitrogen in the sample, which creates more active sites as well as facilitating charge transfer due to the close four-electron reaction pathway. The superior electrocatalytic activity coupled with the facile synthetic method presents a new pathway to cost-effective electrocatalysts for practical fuel cells or metal–air batteries.

关键词： Nitrogen doping Graphene-like carbon nanoflakes Electrocatalyst Oxygen reduction reaction

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Bismuth stabilized by ZIF derivatives for electrochemical ammonia production:Proton donation effect of phosphorus dopants

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Nano Research 2023年第4期16卷 4574-4581页

作者： Qiaoling Wu Ying Sun Qin Zhao Hui Li Zhengnan Ju Yu Wang Xiaodong Sun Baohua Jia Jieshan Qiu Tianyi Ma Institute of Clean Energy Chemistry Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials of Liaoning ProvinceCollege of ChemistryLiaoning UniversityShenyang 110036China School of Science RMIT UniversityMelbourneVIC 3000Australia College of Chemical Engineering State Key Laboratory of Chemical Resource EngineeringBeijing University of Chemical TechnologyBeijing 100029China

N2 electroreduction reaction(NRR)offers a feasible and promising alternative for NH_(3)production by using clean energy ***,it is still obstructed by the pretty low NH3 yield rate and Faradaic efficiency(FE)primarily due to the undesired competing hydrogen evolution reaction and the extremely stable N≡N ***,bismuth nanoparticles were successfully embedded in N and P co-doped carbon nanoflakes(Bi/NPC)by high-temperature pyrolyzation of Bi-zeolitic imidazole frameworks(ZIF)followed by phosphorization,and used as a high-efficiency catalyst toward N2 electroreduction to *** 0.1 M KHCO_(3)electrolyte,Bi/NPC exhibits excellent NRR performances,including a high NH3 yield rate of 3.12μg·h^(−1)·cm^(−2)(−0.6 V *** hydrogen electrode(RHE)),an outstanding FE of 13.58%(−0.4 V ***),and a remarkable stability up to 36 h under ambient *** outstanding NRR catalytic activity is mainly attributed to the intrinsic electrocatalytic NRR activity combined with the inert hydrogen evolution reaction(HER)activity of Bi,the adsorption and activation of N2 facilitated by N dopants,as well as the superior conductivity and the large specific surface area of the two-dimensional layered carbon ***,the hydrogen source provided by P dopant promotes the hydrogenation of the adsorbed N,which further boosts the NRR performance in alkaline *** ultralong durability of Bi/NPC is attributed to the highly dispersed bismuth catalytic active centers confined in the skeleton of N and P co-doped carbon nanoflakes,which inhibits the agglomeration of bismuth *** work presents a novel avenue for designation and fabrication of high-performance Bi-based electrocatalysts for NRR.

关键词： N2 reduction bismuth N P co-doped carbon nanoflakes electrocatalysis

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