纳米颗粒负载碳纳米纤维的制备及 电催化研究

FABRITION AND ELECTROCATALYSIS OF NANOPARTICLES SUPPORTED ON CARBON NANOFIBERS

卢振东

11930370

硕士

材料工程

曾林

2021

2021年6月21日

南方科技大学

深圳

发展氢能经济受到了全球范围内的广泛关注，同时也是改变中国的能源消费 结构的重要环节，其关键因素在于氢能在整个循环体系的利用以及再生。燃料电 池发电以及电解水是氢气高效循环过程中重要的两个步骤。而燃料电池以及电解 水的电催化反应仍然需要高效的电催化剂。目前所使用的商业 Pt/C 催化剂虽然催 化活性好，但是通常其载量高导致成本高、同时其长期稳定性有待于提高。因此， 急需开发合成方法简单、催化活性高、载量低以及长期稳定性好的电催化剂来促 进燃料电池和电解水制氢的发展。本论文介绍了燃料电池、电解水以及静电纺丝 制备催化剂等研究进展，主要研究了（1）静电纺丝过程中各个参数对合成的碳纳 米纤维形貌的影响；（2）通过静电纺丝方法合成低载量、活性高的 Pt 基碳纳米纤 维催化剂，并有效的用于燃料电池的氧还原反应以及电解水制氢的析氢反应。 本课题使用控制变量法探究了电纺过程中不同参数对静电纺丝所制碳纳米纤 维形貌、纤维直径的影响并使用理化分析技术对碳纳米纤维进行表征。研究表明， 当选用聚丙烯腈（PAN）浓度为 10%、工作电压为 16 kV 以及湿度为 25%RH 时， 所制备的碳纳米纤维直径均匀分布在 160-240 nm 之间，形貌最好，无缠结等现象。 通过将乙酰丙酮铂、PAN、聚甲基丙烯酸甲酯（PMMA）以及氰胺溶解在 N-N 二甲基甲酰胺（DMF）中形成前驱体溶液。经预氧化、碳化等步骤，成功的制备 了低铂载量的碳纳米纤维催化剂。制备的 Pt/CNF（NH3-2）用于析氢反应催化活性 最高。在 Pt 载量仅为 5.8 wt%时，在电流密度为 10 mA/cm2时，对应的过电位仅有 34 mV，其塔菲尔斜率为 53.8 mV/dec，性能与商业 20 wt%Pt/C 相当。 通过将乙酰丙酮铂和乙酰丙酮镍的混合盐溶液均匀的喷涂在碳纳米纤维表 面。然后在不同气氛以及温度下进行还原，成功的制备了低铂载量的铂镍负载的 碳纳米纤维催化剂。由于 Pt 与 Ni 的配位效应，有效地提高了析氢反应和氧还原反 应的活性。其中 PtNi/CNF（NH3-560）纤维上均匀分布着大小为 5-8 nm 的铂镍纳 米颗粒。当 Pt 的载量为 5.4 wt%时，10 mA/cm2 的过电位仅有 7 mV，塔菲尔斜率 只有 24.5 mV/dec，析氢性能优于商业 20 wt%Pt/C。氧还原方面，在铂载量仅为商 业 20 wt% Pt/C 的 1/4 时，其氧还原反应曲线的极限电流密度为 5 mA/cm2，半波电 位为 0.82 V，质量活性大于商业 20 wt%Pt/C（0.15 A/mgPt vs 0.14 A/mgPt）。

The development of hydrogen economy has received extensive attention worldwide, and it is also an important essential in changing China's energy consumption structure.The critical factor is the utilization and regeneration of hydrogen energy in the entire recycling system.However,electrocatalytic reactions of fuel cells and electrolysis water still need efficient electrocatalysts. Although the commercial Pt/C catalysts have good catalytic activity, their high loading usually leads to high cost and their stability needs to be improved. Therefore, there is an urgent need to develop catalysts with simple synthesis methods,high catalytic activity, low loading and good stability to promote the further development of fuel cell and electrolytic water hydrogen production. This thesis reviews some progress of fuel cells,water electrolysis, and catalysts fabricated by electrospinning.The thesis focuses on: (1) the influence of various parameters in the electrospinning process on the morphology of the synthesized carbon nanofiber; (2) the electrospinning method to synthesize a low-load, high-activity Pt-based carbon nanofiber catalyst, and can be effectively used in the oxygen reduction reaction of fuel cell and the hydrogen evolution reactions of electrolytic water. The control variable method was used to explore the effects of different parameters on the morphology and diameter of carbon nanofibers ， and using physicochemical analysis techniques to characterize carbon nanofibers.Experimental results show that when the PAN concentration is 10%, the working voltage is 16 kV, and the humidity is 25%RH, the fiber diameter of prepared carbon nanofibers are evenly distributed between 160-240 nm,and with an uniform morphology. The precursor solution is prepared by dissolving Pt(acac)2, polyacrylonitrile, polymethyl methacrylate, and cyanamide in N,N-dimethylformamide. After pre-oxidation, carbonization and other steps, carbon nanofiber catalysts with low platinum loading were successfully prepared. Among them, Pt/CNF（NH3-2） has the highest catalytic activity for hydrogen evolution reaction.When the Pt loading is only 5.8 wt%,the overpotential of 10 mA/cm2 is 34 mV, and Tafel slope is only 53.8 mV/dec，which is comparable to that of commercial catalysts（20 wt% Pt/C）.Abstract III The mixed salt solution of Pt(acac)2 and Ni(acac)2 is uniformly sprayed on the surface of carbon nanofibers. Through reduction in different atmospheres and temperatures, a platinum-nickel supported carbon nanofiber catalyst with low platinum loading was successfully prepared. Due to the coordination effect of Pt and Ni,the activity of hydrogen evolution reaction and oxygen reduction reaction was effectively improved.Among them, nanoparticles of 5-8 nm size are uniformly distributed on the surface of PtNi/CNF(NH3-560) and the Pt loading is only 5.4 wt%.The overpotential of 10mA/cm2 is 7 mV and Tafel slope is only 24.5 mV/dec. The hydrogen evolution performance is better than commercial catalysts (20 wt% Pt/C).In the aspect of oxygen reduction, when the current density is 10 mA/cm2, the overpotential is only 7 mV. When the Pt loading is only 1/4 of the commercial 20 wt% Pt/C, the limiting current density of the oxygen reduction reaction curve is 5 mA/cm2, and the half-wave potential is 0.82 V， The mass activity is greater than commercial 20 wt%Pt/C (0.15 A/mgPt vs 0.14 A/mgPt).

氢能经济 静电纺丝 低铂量 析氢催化剂 氧还原催化剂

hydrogen energy economy electrospinning low platinum content hydrogen evolution catalyst oxygen reduction catalyst

中文

独立培养

南方科技大学

卢振东. 纳米颗粒负载碳纳米纤维的制备及 电催化研究[D]. 深圳. 南方科技大学,2021.