3D NiO nanowalls are homogeneously grown on macroporous nickel foam by a hydrothermal method. The morphology of the NiO nanowalls are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the phase structure of NiO nanowalls is characterized by X-ray diffraction (XRD) analysis. The results indicate that the NiO nanowalls are uniformly distributed on the entire nickel foam framework. And ammonia fluoride has significant influence on the height and thickness of NiO nanowalls. With the presence of ammonia fluoride, NiO nanowalls with height of 4.6 (±0.4) μm and thickness around 50 nm were obtained, while the height and thickness decreased to 1.7 (±0.2) μm and around 20 nm without the presence of ammonia fluoride. The NiO nanowalls were used as electrodes for urea oxidation in alkaline condition. The electro-oxidation activity the catalyst is investigated by cyclic voltammetry and potential step chronoamperometry. The electrocatalytic performance of NiO electrodes depends strongly on the sample preparation condition. The 3D NiO nanowalls electrode exhibit excellent electro-oxidation activity towards urea oxidation. The morphology of the electrodes has significant influence on their activity. The current density of 3D NiO nanowalls electrode prepared with NH₄F at 0.7 V reached 800 mA cm⁻², which was over 4 times than that of sample prepared without NH₄F. Moreover, NiO nanowalls prepared with NH₄F was more stable than the one prepared without NH₄F, which did not show any appreciable morphology change after being used for urea electro-oxidation for 12 h. While the one prepared without NH₄F collapsed after used.

3D NiO纳米壁通过水热法在大孔镍泡沫上均匀生长。通过扫描电子显微镜（SEM），透射电子显微镜（TEM）表征NiO纳米壁的形态，并通过X射线衍射（XRD）分析表征NiO纳米壁的相结构。结果表明，NiO纳米壁均匀分布在整个镍泡沫骨架上。氟化氨对NiO纳米壁的高度和厚度有重要影响。在存在氟化氨的情况下，获得了高度为4.6（±0.4）μm，厚度约为50 nm的NiO纳米壁，而在没有氟化氨的情况下，其高度和厚度减小至1.7（±0.2）μm，厚度约为20 nm。NiO纳米壁用作碱性条件下尿素氧化的电极。通过循环伏安法和电位阶跃计时电流法研究了催化剂的电氧化活性。NiO电极的电催化性能在很大程度上取决于样品制备条件。3D NiO纳米壁电极对尿素氧化表现出出色的电氧化活性。电极的形态对其活性有重大影响。NH制备的3D NiO纳米壁电极的电流密度₄ ˚F为0.7V时达到800毫安厘米^-2，其不经NH制备比样品的4倍以上₄ F.此外，氧化镍纳米墙用NH制备₄ F的一个比没有NH制备更稳定的₄ F，其做在用于尿素电氧化12小时后，未显示任何明显的形态变化。而没有NH ₄ F的制备物在使用后崩溃了。