Catalytic activity of Pt–CoTiO3 nanocatalysts supported on reduced graphene oxide functionalized with Cr organometallic compounds for the oxygen reduction reaction

Pt–CoTiO 3 nanocatalysts were supported on RGO functionalized with the Cr(CO) 6 and [(ƞ 6 -C 6 H 6 )Cr(CO) 6 ] organometallic compounds and characterized for the oxygen reduction reaction (ORR). Different stoichiometric ratios of Cr(CO) 6 gave mono- and bis-hexahapto complexes (RGO-Cr tric and RGO 2 Cr) as a result of the displacement of the carbonyl groups, resulting in the Pt–CoTiO 3 /RGO-Cr tric and Pt–CoTiO 3 /RGO 2 Cr nanocatalysts. In the reaction with (ƞ 6 -C 6 H 6 )Cr(CO) 3 , the arene ligand was retained and the three carbonyl groups disappeared, forming the RGO-Cr bz complex (i.e., Pt–CoTiO 3 /RGO-Cr bz ). During the evaluation of catalytic activity for the ORR, Pt–CoTiO 3 /RGO-Cr bz showed superior mass and specific activities for the ORR compared to the other nanocatalysts. Characterization of Pt–CoTiO 3 /RGO-Cr bz showed that Cr 4+ , Cr 3+ , and Cr 6+ are formed after functionalization. The results in this work demonstrated that functionalization of RGO with Cr organometallic compounds enhances the catalytic activity for the ORR of nanocatalysts with application in anion exchange membrane fuel cells (AEMFC). Graphic abstract