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Hierarchical nitrogen-doped porous hollow carbon spheres (HNPHCS) with porous-thin mesoporous shell and hollow macroporous core structure have been prepared via in-situ oxidation polymerization method using polyaniline as the precursor. After carbonization at 900 °C, the average diameter of HNPHCS is ca. 140 nm with shell thickness of ∼1 nm. Pt nanoparticles with high dispersion and small size have been successfully deposited on the HNPHCS by a microwave-assisted polyol process to synthesize Pt/HNPHCS catalyst. The obtained samples are characterized by physical characterization and electrochemical measurements. Electrochemical studies reveal that the prepared Pt/HNPHCS catalyst possesses notably higher catalytic activity and CO-tolerance, and better stability toward methanol electrooxidation in comparison with Pt/nitrogen-doped porous carbon and the commercial Pt/C catalysts. It is likely that enhanced catalytic properties of the Pt/HNPHCS could be due to the high dispersion of small Pt nanoparticles, the presence of nitrogen species, developed porous-thin mesoporous shell and hollow macroporous core structure of support HNPHCS. As a result, the as-developed Pt/HNPHCS present attractive advantages for the application in fuel cell electrocatalyst. [ABSTRACT FROM AUTHOR]

Nitrogen, phosphorus and Fe doped carbon nanospheres have been synthesized by a facile method in which polyacrylonitrile nanospheres are pyrolyzed in the presence of diammonium phosphate and iron trichloride hexahydrate. The specific surface area of the catalyst is high up to 771.3 m 2 g −1 , and it has a hierarchical micro-meso-macroporous structure. In an alkaline medium, the catalyst exhibits high electrocatalytic activity towards the oxygen reduction reaction (ORR) as well as excellent stability and methanol tolerance—superior in each case to commercial Pt/C catalyst. The effects that adding Fe salt and phosphorus on the structure and performance of the catalyst are also investigated. We suggest that the catalyst's excellent electrocatalytic performance may be attributed to: (1) the synergistic effect, which provides more catalytic sites for the ORR, due to the nitrogen and phosphorus co-doping; (2) the strong promotion by trace Fe residues; and (3) the high surface area and excellent mass transport rate arising from the hierarchical porous structure. [ABSTRACT FROM AUTHOR]

A facile, environmentally friendly and low-cost synthesis strategy is demonstrated to fabricate a MoO 2 /N-doped graphene (MoO 2 /N-GNS) hybrid, in which MoO 2 nanoparticles (NPs) are uniformly dispersed on N-GNS sheets by Mo–N chemical bond formed between MoO 2 and N-GNS. As an anode material in lithium ion batteries, the MoO 2 /N-GNS hybrid possesses superior rate capability, excellent cycling performance as well as high reversible capacity. A reversible capacity of 1138.5 mA h g −1 is maintained after 60 cycles at a current density of 100 mA g −1 , and even at a high current density of 1000 mA g −1 , the specific capacity of 873.7 mA h g −1 can be obtained after 60 cycles. The superior electrochemical performance of the MoO 2 /N-GNS hybrid can be attributed to the synergistic effects of nitrogen-doping, flexible and conductive GNS, and MoO 2 NPs. [ABSTRACT FROM AUTHOR]

In this paper, we report a template-free method to fabricate hollow nitrogen-doped carbon (HNC) by pyrolysis of hollow polyaniline microspheres, which were synthesized by suspension polymerization method. The entire synthesis is simple, environmentally benign, and economic. The oxygen reduction reaction (ORR) activity of the as-prepared HNC catalyst is close to that of the commercial Pt/C catalyst in alkaline media with four electron pathway. Moreover, the HNC shows much better fuel crossover resistance and long-term durability than the commercial Pt/C in alkaline medium. All these features make HNC a potentially promising and suitable substitute for the expensive noble metal catalysts in the next generation alkaline fuel cells. [ABSTRACT FROM AUTHOR]

The plasmonic Ag nanoparticles match with vertically aligned N-doped TiO 2 nanotube arrays, which display improving photoelectrochemical performance. N-doped anatase nanotube arrays are fabricated firstly, and then cubic Ag nanoparticles of diameter 5 nm are deposited on TiO 2 nanotubes without organic additives at room temperature. X-ray photoelectron spectroscopy shows that the oxygen vacancies and N impurity are revealed in N-doped TiO 2 . The electrical properties of samples are investigated by systematic photoelectrochemical measurement. The charge transfer ability of TiO 2 , N-doped TiO 2 and Ag/N-doped TiO 2 is presented directly by Electrochemical impedance spectroscopy and Mott–Schottky measurement, respectively. The carrier density of Ag/N-doped TiO 2 is higher 2 orders of magnitude enhancement of TiO 2 . Furthermore, its photocurrent responds rapidly with illumination owing to fast photoelectron transport. And photocurrent density is 0.14 mA cm −2 at 1.23 V RHE , which is the highest among samples. Finally, the mechanism of improving photoelectrochemical activity is schematically displayed. The plasmonic Ag/N-doped TiO 2 composties are favorable for the separation for photoelectron-hole pairs and increasing electron transfer, leading to a considerably photoelectrochemical performance under sunlight. The modified nanotube arrays provide potential application in photoelectrochemical cell. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) couple functions of waste removal and electricity generation. The future success of MFCs inevitably depends on the increase of performance at decrease of material cost. Therefore, the use of renewable and sustainable materials, e.g. cellulose, to prepare high performance materials for MFCs would be an inevitable trend. In this communication, nitrogen and phosphorus dual-doped carbons were prepared by pyrolysis of cellulose using ammonium phosphate as doping source and employed as oxygen reduction reaction (ORR) catalyst in air-cathode of MFCs. A maximum power density of 2293 ± 50 mW m −2 was generated by the air-cathode using the dual-doped carbon catalyst, which was higher than the air-cathode using Pt/C catalyst with Pt load of 0.5 mg cm −2 (1680 ± 32 mW m −2 ). This study provided a facile and sustainable way to prepare low-cost and high-efficient ORR catalyst for scaled-up MFC applications. [ABSTRACT FROM AUTHOR]