Hetro-Atom Doped CNTs As Metal Free Electrocatalyst for Oxygen Reduction Reaction in Alkaline Fuel Cell

Abstract

Search for eco-friendly sustainable solutions to the alarming energy calamity on both the small and large scale for portable electronic to automobile industry has become one of the most critical challenges on the way to decrease our dependence on traditional fossil fuels based energy sources. In this regard fuel cells provide an alternative solution for clean and green approach. The oxygen reduction reaction (ORR) a half cell reaction taking place at cathode being sluggish in nature requires catalyst to enhance the kinetics. ORR plays a vital role in controlling the performance of a fuel cell. Hence there is a huge demand to develop efficient ORR electrocatalysts for practical applications of the fuel cells. Traditionally, Pt-based electrocatalysts are most suitable for ORR because of their relatively low overpotential and high current density. But the limitation arises because they suffer from serious intermediate tolerance, anode crossover, poor operating stability in an aggressive electrochemical environment. Furthermore, high cost and limited supply hinder wide spread commercialization. This has driven the extensive search for alternative low-cost and high-performance ORR electrocatalysts. Here, we report a facile one-step synthesis of nitrogen-, boron-doped and nitrogen & boron co-doped carbon nanotubes (CNTs) by pyrolysis and used as platinum-free cathode catalyst in direct methanol fuel cell (DMFC). Doped CNTs show excellent catalytic activity and methanol tolerance towards ORR which prompted us to study its fuel cell application. Doped CNTs used as cathode catalyst in DMFC shows comparable performance with the reported results based on state of art commercial platinum catalyst. Overall, the excellent methanol tolerance and good durability of doped CNTs based DMFC suggest a potential to replace platinum for making fuel-cell technology commercially viable.