Boosting the activity and CO tolerance for methanol oxidation reaction in alkaline media by constructing the Pt-TMNs electrocatalysts

Abstract

Developing the efficient and high CO tolerance electrocatalysts is important for methanol oxidation reaction. In this study, a sequence ofcatalysts were constructed by introducting various transition metal nitrides (TMNs) to modify the Pt/C catalyst. The corresponding electrochemical performance were evaluated to investigate the activity, kinetics, charge transfer rate, CO tolerance and stability for MOR in alkaline media. Based on the structural characterization analysis from ICP-MS, XRD, HRTEM and XPS, it could be indicated that the participation of TMNs mainly brought the electronic effect, but not for the geometric effect. The evident difference did not exist in the nanoparticle size, morphology and crystallinity of the related catalysts. After the evaluation on the catalytic performance for alkaline MOR, The TMNs-modified catalysts exhibited higher activity and lower onset potential potential compared with the commercial Pt/C. Among them, Pt-NbN/C showed the highest mass activity with 9.56-fold that of the commercial Pt/C. The faster charge transfer kinetics and reaction rate were confirmed by Tafel and EIS results. CA measurements indicated that they also exhibited higher stability and anti-CO poisoning ability for alkaline MOR, consistent with the CO stripping experiments. To quantitatively describe the realtionship of the electronic effect on the catalytic activity and CO tolerance, the d-band center was employed as a parameter to bulid the corresponding function. Interestingly, it was proposed that the rational d-band center could lead high MOR performance and anti-CO poisoning ability. The introduction of TMNs brought the evident shift of the Pt d-band center and boosted the catalytic activity and anti-CO poisoning ability for alkaline MOR.