In the present work, a simple approach was proposed to produce nanocomposites of nickel nanoparticles decorating graphite flake surface (Ni-NP/graphite) from a ball milling method for methanol electrooxidation reaction. Nickel nanoparticles (Ni-NPs) were obtained after milling for 40 h at 400 rpm. The nanocomposites were prepared blending Ni-NPs and graphite flakes and milling at different ball rotation speeds (100, 200, 300, and 400 rpm). Good agreement between scanning transmission electron microscopy and X-ray diffraction results was found, reporting average particle diameter size of 4.9 nm and average crystallite size of 5.5 nm for Ni-NPs. The methanol electrocatalytic activity and stability of Ni-NPs/graphite nanocomposites were evaluated using cyclic voltammetry and chronoamperometry techniques. The possible methanol electrooxidation mechanism in Ni-NP/graphite nanocomposites was established from deconvolution of the anodic parts of voltammetric curves. The more efficient electrocatalytic activity and stability was found for Ni-NPs/graphite nanocomposite prepared using lower rotation speed (100 rpm). This behavior is associated to the loss of graphite crystallinity and consequently decreasing of its electronic conductivity with the increase of the ball milling energy which is directly related to the rotation speed during decoration procedure.

Graphical Abstract

在目前的工作中，提出了一种简单的方法，该方法通过球磨法进行甲醇电氧化反应，制备装饰石墨鳞片表面（Ni-NP /石墨）的镍纳米粒子的纳米复合材料。以400 rpm研磨40小时后，获得镍纳米粒子（Ni-NPs）。制备纳米复合材料，将Ni-NP和石墨薄片混合并在不同的球转速（100、200、300和400 rpm）下研磨。在扫描透射电子显微镜和X射线衍射结果之间发现了很好的一致性，Ni-NPs的平均粒径为4.9 nm，平均微晶尺寸为5.5 nm。使用循环伏安法和计时电流法技术评估了Ni-NPs /石墨纳米复合材料的甲醇电催化活性和稳定性。通过伏安曲线阳极部分的反卷积，建立了Ni-NP /石墨纳米复合材料中可能的甲醇电氧化机理。发现使用较低的转速（100 rpm）制备的Ni-NPs /石墨纳米复合材料具有更有效的电催化活性和稳定性。这种行为与石墨结晶度的损失有关，并因此随着球磨能量的增加而降低了其电子传导性，而球磨能量的增加与装饰过程中的旋转速度直接相关。

图形概要