Three different aspect ratios (AR = rods length/rods width, AR = 2.8, 3.3, 3.8) of Au nanorods were synthesized and characterized by various measurements. We have evaluated the AR-dependent catalytic properties of Au nanorods using a model reaction based on the reduction of 4-nitrophenol (4-NP) by NaBH₄. From the average reaction rate constants (k) at different temperatures, the activation energy (E_a) was determined. For different aspect ratios of Au nanorods, the larger AR owns the higher k, and the values of E_a increase with decreasing AR, meaning Au nanorods with the higher AR performed the higher catalytic activity. The thermodynamic parameters of entropy (ΔS), Gibbs free energy (ΔG) and activation enthalpy (ΔH) indicated that this catalytic reduction is a non-spontaneous process. The catalytic results of Au nanorods clearly showed that the larger aspect ratio the higher catalytic activity. This substantial difference in AR-dependent catalytic activity can be explained from three different points: The superior catalytic properties of Au nanorods with higher AR result from higher surface-to-volume ratios; Au nanorods with lower AR needs to cross the higher energy barriers; Au nanorods with a larger AR may have higher fractions of uncoordinated surface atoms because of their increased surface curvature.

合成了三种不同的金纳米棒的长宽比（AR =棒长/棒宽，AR = 2.8、3.3、3.8），并通过各种测量对其进行了表征。我们已经使用基于NaBH ₄还原4-硝基苯酚（4-NP）的模型反应，评估了Au纳米棒的AR依赖的催化性能。从不同温度下的平均反应速率常数（k），确定活化能（E _a）。将Au的纳米棒的纵横比不同，较大的AR拥有更高ķ，和的值Ë_一个随增加AR，意味着具有较高AR的Au纳米棒具有较高的催化活性。熵（ΔS），吉布斯自由能（ΔG）和活化焓（ΔH）的热力学参数表明该催化还原是非自发过程。金纳米棒的催化结果清楚地表明，长径比越大，催化活性越高。依赖于AR的催化活性的这种实质性差异可以从三个不同的角度来解释：具有较高AR的Au纳米棒的优异催化性能是由于较高的表面积与体积之比所致。具有较低AR的金纳米棒需要跨越更高的能源壁垒；由于它们的表面曲率增加，具有较大AR的Au纳米棒可能具有较高比例的未配位表面原子。