Nitrogen doped carbons are an important family of materials with ideal activity for oxygen reduction reaction(ORR). It is always interesting to search functional carbons with high heteroatom contents and desirable str...Nitrogen doped carbons are an important family of materials with ideal activity for oxygen reduction reaction(ORR). It is always interesting to search functional carbons with high heteroatom contents and desirable structure for ORR. Within this study, the surface modification of carbon nanotubes(CNTs) via hydrothermal carbonization(HTC) technique in the presence of glucose and urea was reported, where the surface of CNTs is successfully coated by nitrogen containing hydrothermal carbon layers. The resulting composite combines both advantages of the outstanding electrical conductivity of CNTs and the effective ORR active sites provided by doped nitrogen in the HTC carbon layers. By controlling the ratio of glucose and urea, the nitrogen contents coated on the surface of CNTs can reach up to 1.7 wt%. The resulting materials show outstanding electrochemical activity towards ORR in alkaline electrolyte, making it one of the valuable metal-free electrode materials and a competent alternative to the state-of-the-art Pt/C catalyst.展开更多
As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the ad...As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the advantages of ultrahigh atom utilization effciency and surface active energy.However,the fabrication of such matrices(e.g.,well-dispersed single-atom-doped M-N4/NCs)often requires numerous steps and tedious processes.Herein,ultrasonic plasma engineering allows direct carbonization in a precursor solution containing metal phthalocyanine and aniline.When combining with the dispersion effect of ultrasonic waves,we successfully fabricated uniform single-atom M-N4(M=Fe,Co)carbon catalysts with a production rate as high as 10 mg min-1.The Co-N4/NC presented a bifunctional potential drop ofΔE=0.79 V,outperforming the benchmark Pt/C-Ru/C catalyst(ΔE=0.88 V)at the same catalyst loading.Theoretical calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption mechanisms.In a practical Zn-air battery test,the air electrode coated with Co-N4/NC exhibited a specific capacity(762.8 mAh g(-1))and power density(101.62 mW cm^(-2)),exceeding those of Pt/C-Ru/C(700.8 mAh g^(-1) and 89.16 mW cm^(-2),respectively)at the same catalyst loading.Moreover,for Co-N4/NC,the potential difference increased from 1.16 to 1.47 V after 100 charge-discharge cycles.The proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.展开更多
Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （Z...Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （ZIFs, e.g., ZIF-8） via an in situ pyrolysis process. The resultant materials are completely new carbon composites with desirable hierarchical porosity and nitrogen-doped features. Electron microscopy images show that CNTs with small external diameters enable more uniform dispersion of ZlF-8-derived carbons, subsequently yielding a unique hierarchically porous structure. Such carbon shows superior activity in oxygen reduction reaction （ORR） and high performance of supercapacitance, making it a valu- able metal-flee electrode material and a competent alternative to the state-of-the-art Pt/C catalyst. The electrocatalytic performance of CNTs can be dramatically improved by the incorporation of ZIF-8-derived carbons, which is attributed to the combination of good conductivity, abundant accessible dopant species, as well as proper porosity. Our method offers a new avenue for constructing electrocatalysts by effective integration of ZlF-8-derived carbon and the CNTs skeleton.展开更多
基金The Award Program for Fujian Minjiang Scholar Professorship is acknowledged for financial supportfinancial support from the National Natural Science Foundation of China(NSFC Grant number 21571035)
文摘Nitrogen doped carbons are an important family of materials with ideal activity for oxygen reduction reaction(ORR). It is always interesting to search functional carbons with high heteroatom contents and desirable structure for ORR. Within this study, the surface modification of carbon nanotubes(CNTs) via hydrothermal carbonization(HTC) technique in the presence of glucose and urea was reported, where the surface of CNTs is successfully coated by nitrogen containing hydrothermal carbon layers. The resulting composite combines both advantages of the outstanding electrical conductivity of CNTs and the effective ORR active sites provided by doped nitrogen in the HTC carbon layers. By controlling the ratio of glucose and urea, the nitrogen contents coated on the surface of CNTs can reach up to 1.7 wt%. The resulting materials show outstanding electrochemical activity towards ORR in alkaline electrolyte, making it one of the valuable metal-free electrode materials and a competent alternative to the state-of-the-art Pt/C catalyst.
基金supported by Global Frontier Program through the Global Frontier Hybrid Interface materials(GFHIM)of the National Research Foundation of Korea(NRF)funded by the ministry of science,ICT and Future Planning(2013M3A6B1078874)co-supported by Busan Innovation Institute of Industry,Science&Technology Planning(BISTEP)+1 种基金the financial support of Federal Ministry of Education and Research(BMBF)under the“Make Our Planet Great Again-German Research Initiative”(MOPGAGRI),57429784implemented by the German Academic Exchange Service Deutscher Akademischer Austauschdienst(DAAD)。
文摘As bifunctional oxygen evolution/reduction electrocatalysts,transition-metal-based single-atom-doped nitrogen-carbon(NC)matrices are promising successors of the corresponding noblemetal-based catalysts,offering the advantages of ultrahigh atom utilization effciency and surface active energy.However,the fabrication of such matrices(e.g.,well-dispersed single-atom-doped M-N4/NCs)often requires numerous steps and tedious processes.Herein,ultrasonic plasma engineering allows direct carbonization in a precursor solution containing metal phthalocyanine and aniline.When combining with the dispersion effect of ultrasonic waves,we successfully fabricated uniform single-atom M-N4(M=Fe,Co)carbon catalysts with a production rate as high as 10 mg min-1.The Co-N4/NC presented a bifunctional potential drop ofΔE=0.79 V,outperforming the benchmark Pt/C-Ru/C catalyst(ΔE=0.88 V)at the same catalyst loading.Theoretical calculations revealed that Co-N4 was the major active site with superior O2 adsorption-desorption mechanisms.In a practical Zn-air battery test,the air electrode coated with Co-N4/NC exhibited a specific capacity(762.8 mAh g(-1))and power density(101.62 mW cm^(-2)),exceeding those of Pt/C-Ru/C(700.8 mAh g^(-1) and 89.16 mW cm^(-2),respectively)at the same catalyst loading.Moreover,for Co-N4/NC,the potential difference increased from 1.16 to 1.47 V after 100 charge-discharge cycles.The proposed innovative and scalable strategy was concluded to be well suited for the fabrication of single-atom-doped carbons as promising bifunctional oxygen evolution/reduction electrocatalysts for metal-air batteries.
基金supported by the Award Program for Fujian Minjiang Scholar Professorshipthe National Natural Science Foundation of China (21571035)
文摘Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （ZIFs, e.g., ZIF-8） via an in situ pyrolysis process. The resultant materials are completely new carbon composites with desirable hierarchical porosity and nitrogen-doped features. Electron microscopy images show that CNTs with small external diameters enable more uniform dispersion of ZlF-8-derived carbons, subsequently yielding a unique hierarchically porous structure. Such carbon shows superior activity in oxygen reduction reaction （ORR） and high performance of supercapacitance, making it a valu- able metal-flee electrode material and a competent alternative to the state-of-the-art Pt/C catalyst. The electrocatalytic performance of CNTs can be dramatically improved by the incorporation of ZIF-8-derived carbons, which is attributed to the combination of good conductivity, abundant accessible dopant species, as well as proper porosity. Our method offers a new avenue for constructing electrocatalysts by effective integration of ZlF-8-derived carbon and the CNTs skeleton.
基金supported by the National Natural Science Foundation of China(21776129,21706121,and U22B6011)the Natural Science Foundation of Jiangsu Province(BK20170995 and BK20201120)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
