Activated Vacuum Residue for Efficient Oxygen Reduction Reaction in Alkaline Media

Abstract

As a potential replacement for Pt-based materials, the heteroatom-doped and metal-free porous carbons have always been a crucial challenge in modern electrocatalysis. On the other hand, petroleum waste, particularly, vacuum residue presents as a carbon-rich precursor for the development of porous carbons for electrocatalysis. Herein, the new catalysts were prepared from vacuum residue gained from the local petroleum industry. The porous carbons (PCs) as the catalysts were prepared via a simple single route activation at 800 °C and 2 hours in the presence of phosphoric acid. PC possesses a high surface area at ~2200 m2/g with mixed micro- and meso porosities as well as high graphitization content. Spectroscopic analyses reveal up to ~6 % of phosphorous doping content. PCs were tested against oxygen reduction reaction (ORR) as an important challenge in electrochemistry. The structural features and the differences in the activating agents for the development of the PCs were compared to decipher the importance of the doped heteroatoms’ environment in ORR. The ORR efficiency of the electrocatalysts was compared against the commercial 5% Pt/C under alkaline conditions to show the potential of the vacuum residue-derived PCs as the sustainable utilization of petroleum waste.