The physiochemical properties of chars produced by coal pyrolysis in a laboratory-scale fluidized bed reactor with a continuous coal feed and char discharge at temperatures of 750 to 980 ~ C under N2-based atmospheres...The physiochemical properties of chars produced by coal pyrolysis in a laboratory-scale fluidized bed reactor with a continuous coal feed and char discharge at temperatures of 750 to 980 ~ C under N2-based atmospheres containing 02, H2, CO, CH4, and CO2 were studied. The specific surface area of the char was found to decrease with increasing pyrolysis temperature. The interlayer spacing of the char also decreased, while the average stacking height and carbon crystal size increased at higher temperatures, suggesting that the char generated at high temperatures had a highly ordered structure. The char obtained using an ER value of 0.064 exhibited the highest specific surface area and oxidation reactivity. Rela- tively high 02 concentrations degraded the pore structure of the char, decreasing the surface area. The char produced in an atmosphere incorporating H2 showed a more condensed crystalline structure and consequently had lower oxidation reactivity.展开更多
The activity and durability of electrocatalysts are important factors in their practical applications, such as electrocatalytic oxygen evolution reactions （OERs） used in water splitting cells and metal-air batteries...The activity and durability of electrocatalysts are important factors in their practical applications, such as electrocatalytic oxygen evolution reactions （OERs） used in water splitting cells and metal-air batteries. In this study, a novel electrocatalyst, comprising few-layered graphitic carbon （-5 atomic layers） encapsulated heazlewoodite （Ni3S2@C） nanoparticles （NPs）, was designed and synthesized using a one-step solid phase pyrolysis method. In the OER test, the Ni3S2@C catalyst exhibited an overpotential of 298 mV at a current density of 10 mA·cm^-2, a Tafel slope of 51.3 mV·dec^-1, and charge transfer resistance of 22.0 Ω, which were better than those of benchmark RuO2 and most nickel- sulfide-based catalysts previously reported. This improved performance was ascribed to the high electronic conductivity of the graphitic carbon encapsulating layers. Moreover, the encapsulation of graphitic carbon layers provided superb stability without noticeable oxidation or depletion of Ni3S2 NPs within the nanocomposite. Therefore, the strategy introduced in this work can benefit the development of highly stable metal sulfide electrocatalysts for energy conversion and storage applications, without sacrificing electrocatalytic activity.展开更多
文摘The physiochemical properties of chars produced by coal pyrolysis in a laboratory-scale fluidized bed reactor with a continuous coal feed and char discharge at temperatures of 750 to 980 ~ C under N2-based atmospheres containing 02, H2, CO, CH4, and CO2 were studied. The specific surface area of the char was found to decrease with increasing pyrolysis temperature. The interlayer spacing of the char also decreased, while the average stacking height and carbon crystal size increased at higher temperatures, suggesting that the char generated at high temperatures had a highly ordered structure. The char obtained using an ER value of 0.064 exhibited the highest specific surface area and oxidation reactivity. Rela- tively high 02 concentrations degraded the pore structure of the char, decreasing the surface area. The char produced in an atmosphere incorporating H2 showed a more condensed crystalline structure and consequently had lower oxidation reactivity.
基金Acknowledgements This work was financially supported by Australian Research Council （ARC） Discovery Project and the National Natural Science Foundation of China （Nos. 51372248 and 51432009）.
文摘The activity and durability of electrocatalysts are important factors in their practical applications, such as electrocatalytic oxygen evolution reactions （OERs） used in water splitting cells and metal-air batteries. In this study, a novel electrocatalyst, comprising few-layered graphitic carbon （-5 atomic layers） encapsulated heazlewoodite （Ni3S2@C） nanoparticles （NPs）, was designed and synthesized using a one-step solid phase pyrolysis method. In the OER test, the Ni3S2@C catalyst exhibited an overpotential of 298 mV at a current density of 10 mA·cm^-2, a Tafel slope of 51.3 mV·dec^-1, and charge transfer resistance of 22.0 Ω, which were better than those of benchmark RuO2 and most nickel- sulfide-based catalysts previously reported. This improved performance was ascribed to the high electronic conductivity of the graphitic carbon encapsulating layers. Moreover, the encapsulation of graphitic carbon layers provided superb stability without noticeable oxidation or depletion of Ni3S2 NPs within the nanocomposite. Therefore, the strategy introduced in this work can benefit the development of highly stable metal sulfide electrocatalysts for energy conversion and storage applications, without sacrificing electrocatalytic activity.
