Synthesis and functionalization of green carbon as a Pt catalyst support for the oxygen reduction reaction

This study investigates the synthesis and characterization of a carbon derived by a simple combustion process of natural camphor. Resulted carbon was subjected to a chemical (HNO₃ and KOH) and physical treatment (thermal treatment -TT, liquid Nitrogen treatment - LN2) for surface functionalization. Synthesized carbon materials were used as Pt catalyst support for the oxygen reduction reaction (ORR) in acid media. Physicochemical characterization of the carbon support was performed by multiple techniques such as, SEM, EDAX, FTIR, and Raman spectroscopy. Results conducted to spherical particles of camphor carbon (CC) with 50-60 nm in size. The chemical composition revealed a CC without sulfur content. This could be an advantage for avoiding the sulfur poisoning on the Pt surface. FTIR results shows that the oxidative chemical treatment (HNO₃ and KOH) incorporate functional group of C=O to CC. However, the TT eliminates the functional surface group on the CC. Apparently CC and CC-LN2 samples have the same behaviour, consequently it can be inferred that the cryogenic treatment with liquid nitrogen does not significantly modify the functional chemistry of carbon surface. Raman spectroscopy reveals the disorder in the CC (I_D/I_G = 1.01) which is lesser than the Vulcan Carbon (I_D/I_G = 1.16) defect. Furthermore, the chemically treated CC and LN2 shows fewer defects than the thermally treated CC. Electrochemical results show that materials with enhanced specific catalytic activity toward the ORR follow the tendency: Pt/CC-KOH > Pt/CC-TT > Pt/CC > Pt/CC-LN2 > Pt/Vulcan > Pt/C Etek > Pt/CC-HNO₃. Our finding results open a new avenue for carbon from natural source as an effective ORR catalyst support.