Encompassing ecological and economic concerns, the utilization of biomass to produce carbonaceous materials has attracted intensive research and industrial interest. Using nitrogen containing precursors could realize ...Encompassing ecological and economic concerns, the utilization of biomass to produce carbonaceous materials has attracted intensive research and industrial interest. Using nitrogen containing precursors could realize an in situ and homogeneous incorporation of nitrogen into the carbonaceous materials with a controlled process. Herein, N-doped hollow core-disordered mesoporous shell carbonaceous nanospheres （HCDMSs） were synthesized from glucosamine hydrochloride （GAH）, an applicable carbohydrate-based derivative. The obtained HCDMSs possessed controlled size （-450-50 nm） and shell thickness （-70-10 nm）, suitable nitrogen contents （-6.7-4.4 wt.%）, and Brunauer-Emmett-Teller （BET） surface areas up to 770 m^2.g^-1. These materials show excellent electrocatalytic activity as a metal-free catalyst for the oxygen reduction reaction （ORR） in both alkaline and acidic media. Specifically, the prepared HCDMS-1 exhibits a high diffusion-limited current, and superior durability and better immunity towards methanol crossover and CO poisoning for ORR in alkaline solution than a commercial 20 wt.% Pt/C catalyst.展开更多
Carbon nanotubes(CNTs)work as the promising components of miniature electromechanical systems due to their ecellent performances from individual to bundle scales.But it's challenging to achieve precise patterning ...Carbon nanotubes(CNTs)work as the promising components of miniature electromechanical systems due to their ecellent performances from individual to bundle scales.But it's challenging to achieve precise patterning at nanoscale resolution with controlled position and orientation.Here,we demonstrate a fluidic strategy to interlace one-dimensional(1D)ultralong CNTs into the crossed pattern in a one-step in-situ process.Semi-circular substrates of different diameters were placed in front of the growth substrate to change the path and momentum of gas flow.Such flow perturbation caused by substrates could be markedly reflected within a micro-channel reactor,which led to formation of crossed utralong CNTs at definite positions.Furthermore,precise control over the crossing angle as well as the diameter distribution of CNTs was achieved by varying the CNT length and diameter of semi-circular substrates.Our strategy has offered a feasible route for production of crossed ultralong CNTs and will contribute to multidimensional fluidic assembly of flexible nanomaterals.展开更多
基金Financial support from the National Natural Science Foundation of China （Ul162124 ＆ 21376208）, the Zhejiang Provincial Natural Science Foundation for Distinguished Young Scholars of China （LR13B030001）, the Specialized Research Fund for the Doctoral Program of Higher Education （J20130060）, the Fun- damental Research Funds for the Central Universities, the Program for Zhejiang Leading Team of S＆T Innovation, the Partner Group Program of the Zhejiang University and the Max-Planck Society are greatly appreciated.
文摘Encompassing ecological and economic concerns, the utilization of biomass to produce carbonaceous materials has attracted intensive research and industrial interest. Using nitrogen containing precursors could realize an in situ and homogeneous incorporation of nitrogen into the carbonaceous materials with a controlled process. Herein, N-doped hollow core-disordered mesoporous shell carbonaceous nanospheres （HCDMSs） were synthesized from glucosamine hydrochloride （GAH）, an applicable carbohydrate-based derivative. The obtained HCDMSs possessed controlled size （-450-50 nm） and shell thickness （-70-10 nm）, suitable nitrogen contents （-6.7-4.4 wt.%）, and Brunauer-Emmett-Teller （BET） surface areas up to 770 m^2.g^-1. These materials show excellent electrocatalytic activity as a metal-free catalyst for the oxygen reduction reaction （ORR） in both alkaline and acidic media. Specifically, the prepared HCDMS-1 exhibits a high diffusion-limited current, and superior durability and better immunity towards methanol crossover and CO poisoning for ORR in alkaline solution than a commercial 20 wt.% Pt/C catalyst.
基金the National Key R&D Program of China(Nos.2016YFA0200101 and 2016YFA0200102)the National Natural Science Foundation of China(No.21636005).
文摘Carbon nanotubes(CNTs)work as the promising components of miniature electromechanical systems due to their ecellent performances from individual to bundle scales.But it's challenging to achieve precise patterning at nanoscale resolution with controlled position and orientation.Here,we demonstrate a fluidic strategy to interlace one-dimensional(1D)ultralong CNTs into the crossed pattern in a one-step in-situ process.Semi-circular substrates of different diameters were placed in front of the growth substrate to change the path and momentum of gas flow.Such flow perturbation caused by substrates could be markedly reflected within a micro-channel reactor,which led to formation of crossed utralong CNTs at definite positions.Furthermore,precise control over the crossing angle as well as the diameter distribution of CNTs was achieved by varying the CNT length and diameter of semi-circular substrates.Our strategy has offered a feasible route for production of crossed ultralong CNTs and will contribute to multidimensional fluidic assembly of flexible nanomaterals.
