Development of high-performance nano-catalysts for direct formic acid and formate fuel cell applications

Formic acid is an attractive fuel that can be utilised in direct liquid fuel cells due to its low toxicity, non-flammable, and non-explosive characteristics. Besides, formic acid oxidation is regarded as a model reaction in C1 fuel oxidation study due to the relative simplicity of the reaction mechanism. As a result, intensive studies have been reported on improving the direct formic acid fuel cell (DFAFC) by developing highly efficient nano-catalysts and innovative fuel cell system design. Pt, Pd and their alloy catalysts have been shown to play an essential role in promoting formic acid oxidation. Nevertheless, developing a highly active, stable catalyst for direct formic acid fuel cell application remains a significant challenge.

This thesis reports new insights into reaction mechanisms, as well as Pd-based catalyst development, for formic acid electro-oxidation in acidic and alkaline media. Pure Pd deposited on glassy carbon support was tested in a three-electrode cell with a temperature range of 25℃ to 55℃. CV, CA, and EIS were the main techniques used in this experiment to evaluate the performance of the catalysts. In addition, the analysis of the activation energy (Ea) calculated by peak current density also plays an important role in the characterisation of reaction kinetics. Furthermore, to improve catalyst performance for formic acid and formate oxidation, different kinds of metals such as Bi, Ag, Ru, and Cu have been decorated on Pd to produce binary and ternary catalysts. Binary and ternary catalysts with optimised compositions have exhibited a promising potential for both activity and stability improvement compared to pure Pd catalysts, and fundamental mechanism studies have been performed on the improved catalysts. Moreover, an initial study of using conductive PANI as a catalyst promoter for formic acid oxidation has also been performed, and promising data obtained show its potential for future applications in DFAFC.