Abstract:
The direct methanol fuel cell (DMFC) is considered as one of the promising power hubs to ensure the future global energy demand. The development of an efficient and cost-effective electrocatalyst for methanol electrooxidation (MEO) is one of the keys to make DMFC viable for practical application. Herein, an effort has been made to design a low-cost, noble metal free MEO catalyst. The electrocatalyst is synthesized by a facile ion-exchange of mesoporous zeolite ZSM-5 (Zeolite Socony Mobil 5) with non-precious Ni2+ and Cu2+ ions. The detailed electrocatalytic investigations reveal that the optimum contents of Ni2+ and Cu2+ ions in ion-exchanged mesoporous ZSM-5 (Ni2Cu1-MesoZ) are required to exhibit the best electrocatalytic activity (current density and onset potential). Moreover, the MEO capacity of the developed catalyst is found to be comparatively higher than the state-of-art Pt (20%)/C catalyst. The present electrocatalyst retains the catalytic current density even after 1000 cycles of a test run without any micro-structural change. The high surface area, Brönsted acidity, abundant surface hydroxyl groups, inter-crystalline mesoporosity, effective & optimum incorporation of Ni2+/Cu2+ species in the zeolite matrix provide highly dispersed electroactive sites and fast analyte diffusion resulting in a noteworthy MEO kinetics. The CO-stripping analysis also indicates that Ni2Cu1-MesoZ has a high tolerance to CO poisoning which is one of the prime reasons for high MEO activity. The underlying results demonstrate that the impressive electrocatalytic activity and high stability of Ni2+-Cu2+ ion-exchanged mesoporous ZSM-5 would be an interesting electrode material for the commercial methanol fuel cell application. Most importantly, the present study will open up a new avenue in the MEO electrocatalyst development due to its ease of synthesis, scale-up, fabrication, stability/durability, and efficient electrocatalytic activity for alkaline direct methanol fuel cell.
