氮掺杂PtCo/C合金催化剂的研究

Study on Nitrogen-doped PtCo/C Alloy Catalyst

通过调节氮原子在商业化PtCo/C中的含量来调整催化剂的活性和稳定性,最终使催化剂的质量比活性(MA)提升为改性前的2倍,半波电势由0.90 V增加到0.93 V,并且在0.6~1.0 V之间进行5000次循环之后,半波电势下降幅度由原来的66 mV降低到26 mV,表现出优异的氧还原反应活性和出色的循环稳定性.活性的提升主要归因于氮与铂的结合降低了对含氧中间体的吸附结合能,提高了氧还原反应(ORR)过程中羟基的脱附速率.耐久性的提高表明Pt—N键的存在使催化剂不容易在循环过程中溶解,有助于合金催化剂在碳载体上的稳定.

The modification of alloy catalysts to achieve the activity required for the commercialization of proton exchange membrane fuel cells(PEMFCs)has attracted extensive attention in recent years.The performance of PtM(M=transition metal)nanomaterials as catalysts for oxygen reduction reaction(ORR)in PEMFC is higher than that of pure Pt,but there is room for improvement.Nonmetallic elements have a good affinity with platinum and can be added to catalysts.In this study,the activity and stability of the catalyst were enhanced by adjusting the content of nitrogen atoms in commercial PtCo/C.Finally,the MA of the catalyst was increased twice as much as before modification,the half-wave potential increased from 0.90 V to 0.93 V,and after 5000 cycles between 0.6 V and 1.0 V,the drop of half-wave potential decreased from 66 mV to 26 mV,showing excellent ORR activity and stability.The improvement of the activity was mainly attributed to the decrease of the adsorption binding energy of the oxygen-containing intermediates and the increase of the desorption rate of the hydroxyl group in the ORR process.The improved durability indicates that the presence of Pt—N bond makes the catalyst less likely to dissolve during the cycle,which contributes to the stability of the alloy catalyst on the carbon support.This experiment provides an effective treatment strategy for improving the activity and durability of alloy catalyst.