An efficient and durable novel catalyst support with superior electron-donating properties and fuel diffusivity for a direct methanol fuel cell

Abstract

The direct methanol fuel cell (DMFC) is projected as one of the most promising next-generation fuel cell technologies and reducing the catalyst loading at the anode side with an improvement in the sluggishness of methanol oxidation has become the key research topic in the field. For superior catalytic activity towards the methanol oxidation, uniform catalyst particle distribution on the support material without any agglomeration is highly desirable. As of now, a clear understanding of the basic interfacial properties of the catalyst–catalyst support has not been achieved. Herein, we present the evidence that the methanol oxidation reaction (MOR) kinetics can be increased by employing nitrogen-doped partially exfoliated carbon nanotubes (PECNTs) as an efficient anode catalyst support material for DMFCs wherein the partial exfoliation of CNT gives rise to abundant straight edges which possess superior electron-donating properties and can also act as active anchoring sites for catalyst dispersion. Further, DFT calculations reveal that doping nitrogen in the PECNT framework significantly reduces the LUMO–HOMO energy gap. The physical properties elucidate a significant enhancement in the specific surface area and an increment of about ten times in pore size leads to improved methanol diffusion, thereby resulting in an increase in the number of triple phase boundaries and methanol oxidation reaction (MOR) kinetics at the anode. The enhancement in diffusion coefficient leads to a reduction in the mass transfer losses during the full cell measurement, which results in a maximum power density of 92 mW cm⁻² at 80 °C, clearly indicating yet another promising application of PECNTs.