The synthesis, characterization, and performance of carbon nanotubes and carbonnanofibres with controlled size and morphology as a catalyst support material for apolymer electrolyte membrane fuel cell

Abstract

Carbon nanotubes (CNTs) and carbon nanofibres (CNFs) were synthesized by the thermalchemical vapour deposition (CVD) process using an Ni–MgO catalyst. The Ni–MgOcatalyst was treated by a mechanochemical (MC) process to govern its size and morphology.The grinding time in the MC process and pyrolytic temperature in the CVD process areregarded as the main factors to tailor the size and morphology of the CNTs and CNFssynthesized. CNTs with a diameter 25 and 15 nm, twisted CNFs with a diameter 65and 100 nm, and straight CNFs with a diameter 70 nm were synthesized. Afterpurification, they were used as the electrode platinum support for fuel cell application.20% Pt was loaded on the CNTs and CNFs. The fuel cell performance with twistedCNFs was found to be better than that with straight CNFs, and the performanceof CNTs and CNFs with smaller diameter was better than that of bigger ones.The best performance of the fuel cell voltage of 645 mV at a current density of500 mA cm−2 was given by twisted CNFs with diameter 65 nm. The dispersal of the loaded Pt and theresistivity of the membrane electrode assembly were considered to affect their performance.