An in-situ assessment of post-synthesis thermal annealing of platinum nanoparticles supported on graphene

The catalytic activity of as-synthesised nanoparticles is hindered by several factors such as impurities and lattice imperfections. Often, a post-synthesis treatment is mandatory to optimize the performance of these particles but little is known in regards to what this does to them. Here, graphene-supported platinum (Pt) nanoparticles were subjected to thermal annealing in a reductive atmosphere. Surface migration and re-structuring of the particles were observed through in-situ structural and chemical analysis. In addition, residual organic impurities were removed, though the oxide layer coating the Pt surface is not eliminated. Notwithstanding, the interaction of the nanoparticles and the substrate improved with the annealing step, and so did their electrochemically active surface area (ECSA). In these circumstances, better catalytic performance in nano-scaled Pt systems may be a result of the enhancement in ECSA and catalyst-substrate interaction, as opposed to the commonly used argument of surface oxide removal.