氢气与氮气对硼碳氮纳米管生长的影响

The effect of hydrogen and nitrogen on the growth of boron carbonitride nanotubes

在对不同温度和不同催化剂对硼碳氮 (BCN)生长影响研究的基础上 ,进一步研究了氮气与氢气对高温热解法制备BCN纳米管结构、产量等的影响 .实验中发现氮气在制备过程中只对BCN纳米管的产量有微小影响 ,对所生成的纳米管的结构有一定影响 ,气流量太小时 ,乙二胺的转化率低 ,气流量太大时 ,会在所生成的BCN纳米管管壁上出现断裂生长现象 .与氮气不同的是氢气不仅对所生成的纳米管的结构有很大影响 ,还对产量有明显影响 ,当制备过程中没有氢气时 ,所生成的BCN纳米管有明显的弯曲 ,甚至出现了急剧的弯折 ,大部分管壁附着无定形碳 ,还伴随中空管的出现 ;当氢气流量为 4 0sccm时 ,所生成的BCN纳米管的管壁较薄 ,管壁平滑干净 ,没有明显的无定形碳 ,“竹节”规律性较强 ,而当氢气流量继续增大至 80sccm时 ,所生成的BCN纳米管管壁较氢气流量为 4 0sccm时更薄 ,但是此时生成的纳米管的“竹节”变厚 ,并且更加弯曲 ,但是间距规律性减弱 ,在有些纳米管的管壁也出现了断裂现象 .根据实验分析 ,认为在高温热解法制备BCN纳米管时 ,氮气流量应该控制在 15 0— 2 10sccm范围内 ,氢气流量应该在 4 0sccm附近 .

On the basis of the study of different temperature and catalyst, the effect of hydrogen and nitrogen on the morphology and yield of boron carbonitride(BCN) nanotubes produced by thermal decomposition at 860℃ was studied. It is found that nitrogen has a little effect on the growth of BCN nanotubes. Different from nitrogen, transmission electron microscopy(TEM) images reveal that hydrogen is important to the growth of BCN nanotube. Bamboo-shaped thinner wall nanotubes with higher yield are produced with hydrogen flow rate of 40 sccm, whereas curved nanotubes with lower yield and are generated with hydrogen flow rate of 0 sccm. BCN nanotubes with some holes on were produced with the flow rate of 80 sccm. Basic on previous analysis, we think that the appropriate range of N 2 should be 150—210 sccm, and that of H 2 should be about 40 sccm. At last, the reasons were also analysised.