Hybrid Carbon Supports Composed of Small Reduced Graphene Oxide and Carbon Nanotubes for Durable Oxygen Reduction Catalysts in Proton Exchange Membrane Fuel Cells

Abstract

We demonstrated highly active and durable hybrid catalysts (HCs) composed of small reduced graphene oxide (srGO) and carbon nanotubes (CNTs) for use as oxygen reduction reaction (ORR) catalysts in proton exchange membrane fuel cells. Pt/srGO and Pt/CNTs were prepared by loading Pt nanoparticles onto srGO and CNTs using a polyol process, and HCs with different Pt/CNT and Pt/srGO ratios were prepared by mechanically mixing the two components. The prepared HCs consisted of Pt/CNTs well dispersed on Pt/srGO, with catalyst HC55, which was prepared using Pt/srGO and Pt/CNTs in a 5:5 ratio, exhibiting excellent oxygen reduction performance and high stability over 1000 cycles of the accelerated durability test (ADT). In particular, after 1000 cycles of the ADT, the normalized electrochemically active surface area of Pt/HC55 decreased by 11.9%, while those of Pt/srGO and Pt/C decreased by 21.2% and 57.6%, respectively. CNTs have strong corrosion resistance because there are fewer defect sites on the surface, and the addition of CNTs in rGO further improved the durability and the electrical conductivity of the catalyst. A detailed analysis of the structural and electrochemical properties of the synthesized catalysts suggested that the synergetic effects of the high specific surface area of srGO and the excellent electrical conductivity of CNTs were responsible for the enhanced efficiency and durability of the catalysts.

Bithiophene as a Sulfur-Based Promotor for the Synthesis of Carbon Nanotubes and Carbon-Carbon Composites

“…For example, such hybrid membranes should provide increased performance as EUV pellicles [ 44 ] or X-ray protective membranes. The high conductivity of materials combined with their morphology, which usually corresponds to an increased amount of surface, might also be attractive for electrocatalytic applications [ 45 , 46 ].…”

Poly(sulfobetaine methacrylate)-Enhanced Anode Catalyst Layer for Highly Efficient Proton Exchange Membrane Fuel Cells under Low-Humidity Conditions

“…There is evidence that Pt particles separate from the support, migrate, and agglomerate around the cracks during testing, which is expected to reduce catalytic activity, resulting in a lower surface area for the reaction during fuel-cell operation and thus an increase in the activation overvoltage. In addition, this is expected to lead to a nonuniform dispersion of fuel and fuel crossover that accelerates carbon-support corrosion and rapidly degrades performance. , Conversely, the ZA2 anode (Figure c), which exhibits the best performance during low-humidity durability testing, maintains sufficient water with its surface remaining unchanged even after 75 h. This is because pSBMA promotes back-diffusion as a water source, thereby maintaining hydration for long periods, even at low humidity. X-ray diffraction (XRD) patterns before and after durability testing further substantiate these observations (Figure S6a,b).…”

“…In addition, this is expected to lead to a nonuniform dispersion of fuel and fuel crossover that accelerates carbon-support corrosion and rapidly degrades performance. 38,39 Conversely, the ZA2 anode (Figure 5c), which exhibits the best performance during low-humidity durability testing, maintains sufficient water with its surface remaining unchanged even after 75 h. This is because pSBMA promotes back-diffusion as a water source, thereby maintaining hydration for long periods, even at low humidity. X-ray diffraction (XRD) patterns before and after durability testing further substantiate these observations (Figure S6a,b).…”