Synthesis of highly active amorphous platinum-based catalysts for methanol electrooxidation

Abstract

Cleaner, greener energy sources are of increasing demands due to the rapid worsening of the global climate. Fuel cells have long been considered a strong contender due to its promise of high efficiency and low cost. The research community has paid paramount attention to the development of fuel cells, a significant portion of which is on improving the catalysts, especially Pt. Among several approaches that have been employed to boost performance of Pt catalysts, amorphous structure is a promising direction. Amorphous structure houses a large amount of lattice defects which contains a plethora of uncoordinated active sites, which have been reported to boost catalytic activity. However, the most common approach to create amorphous structure by alloying with transition metals such as Ni has limitations. Firstly, transition metals are unstable in the working condition of fuel cells. Second, the dissolved metal ions can cause damage to the Nafion membrane of the fuel cell. Induce amorphous structure using non-metals can solve these problems. This strategy has been successfully employed on various metals like Ni, Co, Pd via P-doping. In this thesis, a facile synthesis of transition metal-free amorphous Pt-P nanocatalyst via P-doping was developed. Amorphous structure was induced by lattice strains caused by phosphorus doping at high concentration. The resulting Pt-P nanocatalysts yielded superior catalytic activity compared to commercial PtRu/C for methanol oxidation reaction in both alkaline and acidic conditions. It was also more durable in short-term and long-term chronoamperometry tests than PtRu/C. There is potential of further applications for the synthesized amorphous Pt-P nanocatalysts.