Shujuan Jiang

Nitrogen-Doped Carbon Nanotubes: High Electrocatalytic Activity toward the Oxidation of Hydrogen Peroxide and Its Application for Biosensing

This study compares the electrocatalytic activity of nitrogen-doped carbon nanotubes (NCNTs) with multiwalled carbon nanotubes (MWCNTs). Results indicate that NCNTs possess a marked electrocatalytic activity toward oxygen reduction reaction (ORR) by an efficient four-electron process in the alkaline condition, while the process of MWCNTs is through a two-electron pathway. Meanwhile, NCNTs show a very attractive electrochemical performance for the redox reaction of hydrogen peroxide (H2O2) and could be employed as a H2O2 sensor at a low potential of +0.3 V. The sensitivity of the NCNT-based biosensor reaches 24.5 microA/mM, more than 87 times that of the MWCNT-based one. Moreover, NCNTs exhibit striking analytical stability and reproducibility, which enables a reliable and sensitive determination of glucose by monitoring H2O2 produced by an enzymatic reaction between glucose oxidase/glucose or choline oxidase/choline at +0.3 V without the help of the electron mediator. The NCNT-based glucose biosensor has a linear range from 2 to 140 microM with an extremely high sensitivity of 14.9 microA/mM, and the detection limit is estimated to be 1.2 microM at a signal-to-noise ratio of 3. The results indicate that the NCNTs are good nanostructured materials for potential application in biosensors.

Facile Construction of Pt–Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction Reaction

A straight forward method for immobilizing Pt-Co alloyed nanoparticles onto nitrogen-doped CNx nanotubes is presented. The as-prepared electrocatalysts exhibit good performance for oxygen reduction reaction in acidic medium arising from the high-dispersion and alloying effect of the Pt-Co nanoparticles and the intrinsic catalytic capacity of the CNx nanotubes.

CNx nanofibers converted from polypyrrole nanowires as platinum support for methanol oxidation

A new kind of carbon nitride (CNx) nanofiber has been prepared by the calcination of polypyrrole nanowires at 800 °C. The product maintained a wire-like morphology during calcination, and the pyrrolic nitrogen in the polypyrrole nanowires gradually changed to pyridinic and graphitic nitrogen as annealing temperature increased. These CNx nanofibers, prepared at 800 °C, have a nitrogen concentration of about 10%. Pt nanoparticles with average size of ∼3 nm could therefore be easily immobilized onto the CNx nanofibers because of the inherent chemical activity arising from the nitrogen incorporation. The Pt/CNx composite catalyst thus obtained has a large electrochemically active area and gives good electrocatalytic performance for methanol oxidation, both in activity and stability, suggesting it has potential application in fuel cells.

Growth mechanism, structural regulation and energy-oriented functionalization of carbon-based nanotubes

Summary form only given. By using the in situ thermal analysis-mass spectroscopic technique, the CVD growth process of CNTs with benzene precursor has been clearly illuminated and the six-membered-ring-based growth mechanism through surface diffusion is deduced. Moreover, by applying this mechanism to the synthesis with pyridine precursor, nitrogen-doped CNTs (NCNTs) with predominant pyridinic N over graphitic N have been obtained. And such NCNTs have homogenous distribution of the nitrogen species which is beneficial for the surface functionalization. Accordingly, a series of alloyed Pt-TM (TM=Ru, Co, Ni etc) nanoparticles have been directly immobilized onto the outer surface of the NCNTs without pre-modification due to the nitrogen participation. The Pt-TM nanoparticles in so-constructed binary Pt-TM/NCNTs catalysts own high dispersion, narrow size distribution and tunable chemical composition.

Electrocatalysts: Facile Construction of Pt–Co/CNx Nanotube Electrocatalysts and Their Application to the Oxygen Reduction Reaction (Adv. Mater. 48/2009)

Pt-Co alloyed nanoparticles can be facilely immobilized onto CNx nanotubes due to the incorporated nitrogen, report Yanwen Ma, Zheng Hu, and co-workers on p. 4953. The as-prepared electrocatalysts exhibit good performance for oxygen reduction reactions in acidic media arising from the high dispersion and alloying effect of Pt-Co nanoparticles, as well as the intrinsic catalytic capacity of CNx nanotubes, which is significant for the development of fuel cells.