Onion-like carbon （OLC） was fabricated by annealing nanodiamond at 1000 ℃ for 2 hours in low vacuum （1 Pa）. The OLC was characterized by X-ray diffraction （XRD）, high resolution transmission electron microscopy...Onion-like carbon （OLC） was fabricated by annealing nanodiamond at 1000 ℃ for 2 hours in low vacuum （1 Pa）. The OLC was characterized by X-ray diffraction （XRD）, high resolution transmission electron microscopy （HRTEM）, Fourier transform infrared spectroscopy （FTIR）, Raman spectroscopy and differential scanning calorimetry （DSC）. The experimental results show that the OLC exhibits similarity to the original nanodiamond particles in shape. The size of the OLC is found to be approximately 5 nm. The transformation mechanism of the OLC from nanodiamond was discussed also.展开更多
Graphene oxide(GO)nanosheets and onion‐like carbon(OLC)nanoparticles were synthesized from natural graphite powder and candle soot,respectively,and characterized by transmission electron microscopy and Raman spectros...Graphene oxide(GO)nanosheets and onion‐like carbon(OLC)nanoparticles were synthesized from natural graphite powder and candle soot,respectively,and characterized by transmission electron microscopy and Raman spectroscopy.The lubricating performances of GO and OLC as lubricant additives in water were comparatively evaluated using a ball‐on‐disc tribometer.The effects of sand blasting of a steel disc on its morphology and tribological property were evaluated.The results show that the two nanomaterials,GO and OLC,when used as lubricant additives in water effectively reduce the friction and wear of the sliding discs,which is independent of the disc surface treatment.On applying heavy loads,it is observed that GO exhibits superior friction‐reducing and anti‐wear abilities compared to those of OLC—a trace amount of GO can achieve a lubricating ability equivalent to that of an abundant amount of OLC.Furthermore,it is observed that sand blasting cannot improve the wear resistance of the treated steel disc,even though the hardness of the disc increased after the treatment.The possible anti‐wear and friction‐reducing mechanisms of the GO and OLC as lubricant additives in water are discussed based on results for the wear surfaces obtained by scanning electron microscopy,Raman spectroscopy,and X‐ray photoelectron spectroscopy。展开更多
Onion-like carbon(OLC)was synthesized by annealing nanodiamond in low vacuum of 1 Pa and at annealing temperatures from 500℃to 1400℃.The high-resolution transmission electron microscope (HRTEM)images,X-ray diffracti...Onion-like carbon(OLC)was synthesized by annealing nanodiamond in low vacuum of 1 Pa and at annealing temperatures from 500℃to 1400℃.The high-resolution transmission electron microscope (HRTEM)images,X-ray diffraction(XRD)and Raman spectrum of the OLC showed that there was no OLC when the annealing temperature was lower than 900℃.Moreover,the fragment amorphous carbon existed on the surfaces of the nanodiamond particles.At the annealing temperature of 900℃,the OLC particles began appearing and the size of the OLC particles was smaller than 5 nm.When the annealing temperature was increased from 900℃to 1400℃,the nanodiamond was transformed into OLC gradu- ally.At the annealing temperature of 1400℃,all the nanodiamond particles were transformed into OLC completely.The OLC exhibited similarity to the original nanodiamond particles in shape.A mechanism for the OLC synthesis by annealing was provided.The graphitization started at the surfaces of the nanodiamond particles.The formation process of the OLC includes formation of graphite fragments, connection and curvature of graphite sheets between diamond(111)planes and closure of the graphite layers.展开更多
采用放电等离子烧结系统（spark plasma sintering,SPS）,在温度1100-1400℃、保温0-30 min、升温速度10-30℃/min、真空1 Pa 条件下,退火处理爆轰纳米金刚石（平均粒度尺寸约为5 nm）制得不同结构的圆葱碳。采用 X 射线衍射仪（XRD）...采用放电等离子烧结系统（spark plasma sintering,SPS）,在温度1100-1400℃、保温0-30 min、升温速度10-30℃/min、真空1 Pa 条件下,退火处理爆轰纳米金刚石（平均粒度尺寸约为5 nm）制得不同结构的圆葱碳。采用 X 射线衍射仪（XRD）及高分辨率透射电镜（HRTEM）表征所制得的圆葱碳。结果表明：随着退火温度升高、保温时间延长,圆葱碳转化度升高；升温速率对圆葱碳转化度影响不明显。展开更多
文摘Onion-like carbon （OLC） was fabricated by annealing nanodiamond at 1000 ℃ for 2 hours in low vacuum （1 Pa）. The OLC was characterized by X-ray diffraction （XRD）, high resolution transmission electron microscopy （HRTEM）, Fourier transform infrared spectroscopy （FTIR）, Raman spectroscopy and differential scanning calorimetry （DSC）. The experimental results show that the OLC exhibits similarity to the original nanodiamond particles in shape. The size of the OLC is found to be approximately 5 nm. The transformation mechanism of the OLC from nanodiamond was discussed also.
基金financial support of the National Natural Science Foundation of China(No.21473061)the Guangdong Natural Science Funds for Distinguished Young Scholar(No.2015A030306026)the Science and Technology Planning Project of Guangzhou City(No.201707010055)
文摘Graphene oxide(GO)nanosheets and onion‐like carbon(OLC)nanoparticles were synthesized from natural graphite powder and candle soot,respectively,and characterized by transmission electron microscopy and Raman spectroscopy.The lubricating performances of GO and OLC as lubricant additives in water were comparatively evaluated using a ball‐on‐disc tribometer.The effects of sand blasting of a steel disc on its morphology and tribological property were evaluated.The results show that the two nanomaterials,GO and OLC,when used as lubricant additives in water effectively reduce the friction and wear of the sliding discs,which is independent of the disc surface treatment.On applying heavy loads,it is observed that GO exhibits superior friction‐reducing and anti‐wear abilities compared to those of OLC—a trace amount of GO can achieve a lubricating ability equivalent to that of an abundant amount of OLC.Furthermore,it is observed that sand blasting cannot improve the wear resistance of the treated steel disc,even though the hardness of the disc increased after the treatment.The possible anti‐wear and friction‐reducing mechanisms of the GO and OLC as lubricant additives in water are discussed based on results for the wear surfaces obtained by scanning electron microscopy,Raman spectroscopy,and X‐ray photoelectron spectroscopy。
文摘Onion-like carbon(OLC)was synthesized by annealing nanodiamond in low vacuum of 1 Pa and at annealing temperatures from 500℃to 1400℃.The high-resolution transmission electron microscope (HRTEM)images,X-ray diffraction(XRD)and Raman spectrum of the OLC showed that there was no OLC when the annealing temperature was lower than 900℃.Moreover,the fragment amorphous carbon existed on the surfaces of the nanodiamond particles.At the annealing temperature of 900℃,the OLC particles began appearing and the size of the OLC particles was smaller than 5 nm.When the annealing temperature was increased from 900℃to 1400℃,the nanodiamond was transformed into OLC gradu- ally.At the annealing temperature of 1400℃,all the nanodiamond particles were transformed into OLC completely.The OLC exhibited similarity to the original nanodiamond particles in shape.A mechanism for the OLC synthesis by annealing was provided.The graphitization started at the surfaces of the nanodiamond particles.The formation process of the OLC includes formation of graphite fragments, connection and curvature of graphite sheets between diamond(111)planes and closure of the graphite layers.
文摘将镍铁金属配位聚合物前驱体在惰性气氛下热分解制备了富氮洋葱碳(ONC)包覆的Ni/Ni Fe_2O_4多孔纳米棒复合析氧电催化剂,与Ni@ONC,Ni Fe_2O_4材料及传统Ru O_2催化剂相比,得益于这种富氮洋葱碳包覆的Ni/Ni Fe_2O_4一维多孔纳米异质结构,Ni/Ni Fe_2O_4@ONC材料拥有更优异的导电性能和更大的电化学活性面积(0.149 m F),因而表现出更优异的析氧电催化性能。Ni/Ni Fe_2O_4@ONC纳米棒在1 mol·L^(-1) KOH溶液中,10 m A·cm-2下的析氧过电位仅为299 m V,塔菲尔斜率为73 m V·dec-1,展现出优异的析氧稳定性能。
文摘采用放电等离子烧结系统（spark plasma sintering,SPS）,在温度1100-1400℃、保温0-30 min、升温速度10-30℃/min、真空1 Pa 条件下,退火处理爆轰纳米金刚石（平均粒度尺寸约为5 nm）制得不同结构的圆葱碳。采用 X 射线衍射仪（XRD）及高分辨率透射电镜（HRTEM）表征所制得的圆葱碳。结果表明：随着退火温度升高、保温时间延长,圆葱碳转化度升高；升温速率对圆葱碳转化度影响不明显。
