Abstract Self-polymerization of dopamine, in either an alkaline or an acidic environment, to form polydopamine is a material-independent surface coating technique, influencing almost all areas of material science and engineering. We demonstrated a simple, two-step method to prepare in-situ silver or silver-copper alloy nanoparticles on the surface of reduced graphene oxides, using polydopamine formed in an acidic medium. The acidic medium was created by a nonthermal micro-hollow cathode discharge device and the device was operated at atmospheric pressure, using air as the working gas. The nanocomposites were characterized with SEM, EDX, ICP-OES, and FT-IR; the electrochemical catalytic activity was tested using rotating disk electrode. The characterization methods confirmed the formation of the nanocomposites, which contain polydopamine, reduced graphene oxides, and metal nanoparticles or nanoalloy. We hypothesized that by alloying silver and copper on the surface of reduced graphene oxides, the oxygen reduction reaction (ORR) catalytic activity of the nanocomposites will be enhanced through both alloying and substrate effects. The size range of the nanoparticles is between 10 nm and 15 nm. We find that both the silver and alloy samples catalyze the ORR via a four-electron mechanism. The alloy nanocomposites showed better performance indicator parameters than the silver one, in both mass activity and kinetic current density. This preparation method has paved a new way of synthesizing an ORR catalyst in an environmentally friendly manner.

中文翻译：

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酸性环境下多巴胺自聚合修饰还原氧化石墨烯的银（合金）纳米粒子的制备及电化学性能

摘要 多巴胺在碱性或酸性环境中自聚合形成聚多巴胺是一种与材料无关的表面涂层技术，几乎影响了材料科学和工程的所有领域。我们展示了一种简单的两步法，使用在酸性介质中形成的聚多巴胺，在还原的氧化石墨烯表面上制备原位银或银铜合金纳米颗粒。酸性介质由非热微空心阴极放电装置产生，该装置在大气压下运行，使用空气作为工作气体。纳米复合材料用 SEM、EDX、ICP-OES 和 FT-IR 表征；采用旋转圆盘电极测试电化学催化活性。表征方法证实了纳米复合材料的形成，其中含有聚多巴胺，还原氧化石墨烯和金属纳米颗粒或纳米合金。我们假设通过在还原的氧化石墨烯表面上将银和铜合金化，纳米复合材料的氧还原反应 (ORR) 催化活性将通过合金化和基材效应得到增强。纳米颗粒的尺寸范围在 10 nm 和 15 nm 之间。我们发现银和合金样品都通过四电子机制催化 ORR。合金纳米复合材料在质量活性和动电流密度方面都显示出比银复合材料更好的性能指标参数。该制备方法为以环保方式合成ORR催化剂开辟了新途径。纳米复合材料的氧还原反应 (ORR) 催化活性将通过合金化和基材效应得到增强。纳米颗粒的尺寸范围在 10 nm 和 15 nm 之间。我们发现银和合金样品都通过四电子机制催化 ORR。合金纳米复合材料在质量活性和动电流密度方面都显示出比银复合材料更好的性能指标参数。该制备方法为以环保方式合成ORR催化剂开辟了新途径。纳米复合材料的氧还原反应 (ORR) 催化活性将通过合金化和基材效应得到增强。纳米颗粒的尺寸范围在 10 nm 和 15 nm 之间。我们发现银和合金样品都通过四电子机制催化 ORR。合金纳米复合材料在质量活性和动电流密度方面都显示出比银复合材料更好的性能指标参数。该制备方法为以环保方式合成ORR催化剂开辟了新途径。合金纳米复合材料在质量活性和动电流密度方面都显示出比银复合材料更好的性能指标参数。该制备方法为以环保方式合成ORR催化剂开辟了新途径。合金纳米复合材料在质量活性和动电流密度方面都显示出比银复合材料更好的性能指标参数。该制备方法为以环保方式合成ORR催化剂开辟了新途径。