Self-standing CoFe embedded nitrogen-doped carbon nanotubes with Pt deposition through direct current plasma magnetron sputtering for direct methanol fuel cells applications

Abstract

Herein, ultra-low amount Pt is uniformly deposited on the surface of CoFe nanoparticles (NPs) embedded nitrogen-doped carbon nanotubes which are grown directionally on the surface of carbon fiber cloth (Pt–CoFe@NCNT/CFC) using the direct current plasma magnetron sputtering (DC-PMS) technique. The designed electrode exhibits excellent trifunctional catalytic activities towards oxygen reduction reaction (ORR) (in 0.1 M KOH, E1/2 = 0.807 V; in 0.5 M H2SO4, E1/2 = 0.723 V), hydrogen evolution reaction (HER) (in 1 M KOH, η10 = 17 mV and η100 = 93 mV; in 0.5 M H2SO4, η10 = 42 mV and η100 = 100.5 mV) and methanol oxidation reaction (MOR) (in 0.5 M H2SO4 + 0.5 M CH3OH, peak current density reaches 115 mA mg−1Pt@1.116 V). It is verified that the DC-PMS technique can greatly improve the utilization efficiency of Pt, so as to reduce the dosage of Pt, and shows better catalytic performance and excellent stability than the commercial Pt/C catalysts. The rich hierarchical heterostructures of the designed electrode can provide more non-noble metal active sites, so as to enhance the catalytic activity and further cut down the consumption of noble metals. Impressively, Pt–CoFe@NCNT/CFC electrode assembled direct methanol fuel cell achieved a remarkable maximum power density of 73.41 mW cm−2 and shows excellent stability.