One-step solution-phase synthesis of Co3O4/RGO/acetylene black as a high-performance catalyst for oxygen reduction reaction

Abstract

On the way to become promising oxygen reduction reaction (ORR) catalysts, the hybrids composed of reduced graphene oxide (RGO) and transition metal oxides are suffering from stacking of RGO sheets. In this work, a Co₃O₄/RGO/acetylene black (AB) hybrid was successfully synthesized via a facile one-step solution-phase route with sandwiching of AB particles between the RGO sheets during the synthesis of Co₃O₄/RGO, which can effectively tackle the stacking of RGO sheets. Compared with Co₃O₄/RGO, Co₃O₄/RGO/AB-P (mixing AB with the pre-prepared Co₃O₄/RGO with stirring), Co₃O₄/RGO/AB-M (mixing AB with Co₃O₄/RGO during the fabrication of the Co₃O₄/RGO catalytic layer for ORR) and commercial 10 wt% Pt/C, the Co₃O₄/RGO/AB hybrid exhibits increases of 50.6%, 32.5%, 37.9% and 8.9% in the ORR current density, respectively. This indicates that the introduction strategy of AB to Co₃O₄/RGO plays a vital role in the enhancement of ORR catalytic activity. Moreover, the Co₃O₄/RGO/AB hybrid shows a subtle ascending trend in the ORR current density during continuous operation for 72 000 s, while Pt/C exhibits a 9.0% decrease. The exceptional ORR catalytic performance of Co₃O₄/RGO/AB can also be ascribed to the large specific surface area, well-anchored Co₃O₄ nanoparticles on the RGO sheets, and low ohmic and kinetic impedances for ORR. We hope this work will be conducive for the extensive commercial applications of fuel cells.