层级多孔碳载铂催化剂的制备及可达性

层级多孔碳作为氧还原铂基催化剂载体的选择之一, 简单的旋转圆盘电极(RDE)验证此类催化剂具有较高的氧还原活性, 但几乎都缺少膜电极(MEA)性能验证, 实用性无法保证. 本文设计制备了基于聚苯胺的层级多孔碳（NHPC）载铂催化剂（Pt/NHPC850）, 研究了其氧还原活性、 MEA质子传输和氧传输特性. RDE测试研究表明, Pt/NHPC850催化剂在低I/C（离聚物与碳载体质量比）时的面积活性低于实心碳载铂催化剂（Pt/XC-72）, 但当I/C增大到与膜电极中一致时, 由于Nafion树脂对Pt催化剂的毒化作用增强, 其面积活性反而优于 Pt/XC-72. Pt/NHPC850催化剂的高Pt分散性及其优异的抗Nafion毒化性能, 使其在I/C为0.8时的质量活性为Pt/XC-72催化剂的1.34倍. MEA质子传输研究表明， 即使在高加湿条件下, Pt/NHPC850质子电阻率仍高达72.6 mΩ·cm², 为Pt/XC-72的3倍. Pt/NHPC850制备的膜电极极化曲线在500 mA/cm²电流密度下性能迅速下降, Pt/NHPC850的氧增益电压达到144.4 mV, 比Pt/XC-72高56.7 mV. 表明Pt/NHPC850膜电极的质子传输和氧传输性能较差. 对比Pt/NHPC850催化剂的RDE和MEA的测试结果, 说明以层级多孔碳为载体的铂碳催化剂虽然耐Nafion毒化能力提高, 但是质子和氧气的氧传输性较差, 此类层级多孔碳还需进一步优化其结构, 才有可能满足低铂质子交换膜燃料电池（PEMFC）的应用需求.

Study on Preparation and Accessibility of Hierarchical Porous Carbon Supported Platinum Catalyst

In last decade， hierarchical porous carbon has been one of the choices of platinum-based catalysts supports for oxygen reduction. A simple rotating disk electrode（RDE） proves that this type of catalyst exhibits excellent oxygen reduction activity， but almost all of them lack membrane electrodes（MEA） verification， and the performance practicability cannot be guaranteed. In this paper， a polyaniline-based hierarchical porous carbon（NHPC） platinum-supported catalyst（Pt/NHPC850） was designed and prepared. Taking this as an example， the oxygen reduction activity， MEA proton transport and oxygen transport were studied in detail characteristics. RDE test research shows that the specific activity of Pt/NHPC850 catalyst at low I/C（mass ratio of ionomer to carbon support） is lower than that of solid carbon supported Pt catalyst（Pt/XC-72）. However， when the I/C increases to the same level as the membrane electrode， the specific activity of Pt/NHPC850 catalyst is better than that of Pt/XC-72 due to the enhanced poisoning effect of Nafion resin on the Pt catalyst. The high Pt dispersibility of Pt/NHPC850 catalyst and its excellent resistance to Nafion poisoning make its mass activity at an I/C of 0.8 to be 1.34 times that of Pt/XC-72 catalyst. The proton transport study of MEA shows that even under high humidification， the proton resistivity of Pt/NHPC850 is 72.6 mΩ·cm²， which is three times that of Pt/XC-72. The polarization curve of the membrane electrode prepared by Pt/NHPC850 declines rapidly at a current density of 500 mA/cm². The oxygen gain voltage of Pt/NHPC850 reaches 144.4 mV， which is 56.7 mV higher than Pt/XC-72， indicating that the Pt/NHPC850 membrane electrode presents poor oxygen transport performance. The RDE and MEA evaluations of the Pt/NHPC850 catalyst show that although the platinum-carbon catalyst with hierarchical porous carbon as support has improved resistance to Nafion poisoning， it has poor transport properties for protons and oxygen. This type of hierarchical porous carbon needs to be further optimized to meet the application requirements of low platinum polymer exchange membrane fuel cells（PEMFCs）.