Effect of carbon nanofiber surface groups on oxygen reduction reaction of supported Pt electrocatalyst

Pt nanoparticles supported on the acid-treated carbon nanofiber (CNF-OX) and LiAlH4-treated carbon nanofiber (CNF-OH) are synthesized via ethylene glycol reduction method. The nature of oxygen-containing surface groups on the CNF-OX and CNF-OH is investigated by potentiometric titration and XPS characterization. Titration of the support materials shows that LiAlH4 can effectively convert the carboxylic acid groups (from 0.21 mmol g−1 to 0.06 mmol g−1) to hydroxyl groups (from 0.09 mmol g−1 to 0.17 mmol g−1), which is agreed well with the results of XPS characterization. High resolution transmission electron microscopy (HRTEM) characterization shows that the Pt nanoparticles are highly dispersed on the two modified CNFs, and the Pt nanoparticles supported on the CNF-OH have a smaller particle size and a more uniform particle size distribution. Rotating disk electrode (RDE) analysis reveals that Pt/CNF-OH exhibits a better activity for ORR than Pt/CNF-OX, and this may be associated with the smaller particle size and better dispersion of Pt nanoparticles on the CNF-OH.

► We studied the effect of oxygen-groups on the particle size and deposition of Pt particles. ► Pt/CNF-OH exhibits smaller Pt mean particle size compared with Pt/CNF-OX. ► Pt/CNF-OH/GC electrode exhibits a better ORR activity than Pt/CNF-OX/GC electrode.