碳纳米管表面修饰程度对碳纳米管载Pt电催化性能的影响

比较了用不同温度的浓HNO₃处理的碳纳米管(CNTs)作载体的Pt(Pt/CNTs)对甲醇氧化的电催化活性. 结果表明浓HNO₃处理使CNTs表面修饰上的含氧基团对CNTs上沉积Pt粒子的平均粒径有较大影响. 表面修饰程度适当时, 制得的Pt/CNTs中Pt粒子较小, 因此, 对甲醇氧化的电催化活性较高. 而表面修饰程度过大, 易使Pt粒子团聚, 从而降低Pt/CNTs催化剂对甲醇氧化的电化学活性.

Effect of Surface Modification Extent of Carbon Nanotubes on Electrocatalytic Performance of Carbon Nanotubes Supported Pt catalyst

Based on the synthesis and purification of carbon nanotubes (CNTs), CNTs were treated with concentrated HNO₃ solution at 50, 75, and 100 ℃ for 5 h. After CNTs were treated in concentrated HNO₃ solution at 75 ℃ for 5 h, suitable amount of hydrophilic O-containing surface groups would be formed so that the average size of the Pt particles deposited on the CNTs surface is small, about 3.7 nm, leading to the good electrocatalytic activity of the Pt/CNTs catalyst for the methanol oxidation. If the treatment temperature is as low as 50 ℃, the amount of the hydrophilic O-containing surface groups formed on CNTs is small so that the Pt particles formed on CNTs would be easy to aggregate. If the treatment temperature is as high as 100 ℃, the amount of the hydrophilic O-containing surface groups formed on CNTs is large and the CNTs would be opened. Then, the Pt particles formed on CNTs would be concentrated near the fractures and form large Pt particles, leading to the low electrocatalytic activity of the Pt/CNTs catalyst for the methanol oxidation.