title: Shrimp-shell derived carbon nanodots as carbon and nitrogen sources to fabricate three-dimensional N-doped porous carbon electrocatalysts for the oxygen reduction reaction.
abstract: Development of cheap, abundant and metal-free N-doped carbon materials as high efficiency oxygen reduction electrocatalysts is crucial for their practical applications in future fuel cell devices. Here, three-dimensional (3D) N-doped porous carbon (NPC) materials have been successfully developed by a simple template-assisted (e.g., SiO2 spheres) high temperature pyrolysis approach using shrimp-shell derived N-doped carbon nanodots (N-CNs) as carbon and nitrogen sources obtained through a facile hydrothermal method. The shrimp-shell derived N-CNs with a product yield of ∼ 5% possess rich surface O- and N-containing functional groups and small nanodot sizes of 1.5-5.0 nm, which are mixed with surface acidification treated SiO2 spheres with an average diameter of ∼ 200 nm in aqueous solution to form a N-CNs@SiO2 composite subjected to a thermal evaporation treatment. The resultant N-CNs@SiO2 composite is further thermally treated in a N2 atmosphere at different pyrolysis temperatures, followed by acid etching, to obtain 3D N-doped porous carbon (NPC) materials. As electrocatalysts for oxygen reduction reaction (ORR) in alkaline media, the experimental results demonstrate that 3D NPC obtained at 800 °C (NPC-800) with a surface area of 360.2 m(2) g(-1) exhibits the best ORR catalytic activity with an onset potential of -0.06 V, a half wave potential of -0.21 V and a large limiting current density of 5.3 mA cm(-2) (at -0.4 V, vs. Ag/AgCl) among all NPC materials investigated, comparable to that of the commercial Pt/C catalyst with an onset potential of -0.03 V, a half wave potential of -0.17 V and a limiting current density of 5.5 mA cm(-2) at -0.4 V. Such a 3D porous carbon ORR electrocatalyst also displays superior durability and high methanol tolerance in alkaline media, apparently better than the commercial Pt/C catalyst. The findings of this work would be valuable for the development of low-cost and abundant N-doped carbon materials from biomass as high performance metal-free electrocatalysts.
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn and University of Science and Technology of China, Hefei 230026, China.
authors.forename: Rongrong
authors.initials: R
authors.lastname: Liu
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn.
authors.forename: Haimin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn.
authors.forename: Shengwen
authors.initials: S
authors.lastname: Liu
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn and University of Science and Technology of China, Hefei 230026, China.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn.
authors.forename: Tianxing
authors.initials: T
authors.lastname: Wu
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn and University of Science and Technology of China, Hefei 230026, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Ge
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn and University of Science and Technology of China, Hefei 230026, China.
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Zang
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn and Centre for Clean Environment and Energy, Griffith University, Gold Coast Campus, QLD 4222, Australia.
authors.forename: Huijun
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Materials Physics, Centre for Environmental and Energy Nanomaterials, Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China. zhanghm@issp.ac.cn gzhwang@issp.ac.cn.
authors.forename: Guozhong
authors.initials: G
authors.lastname: Wang