PtNiCo NANOSHEETS SUPPORTED BY SULFONIC GROUPS GRAFTED ON REDUCED GRAPHENE OXIDE AS EFFICIENT ELECTROCATALYSTS FOR OXYGEN REDUCTION REACTION

Abstract

The ternary PtNiCo catalyst grafted by sulfonic group on reduced graphene oxide (RGO–SO3H) was prepared by a simple solvothermal method. The sheets of nanostructure were stacked in the shape of near-sphere by field-emission scanning electron microscope (FESEM). X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy were carried out to explore the phase structure, element analysis and carbon hybridization, respectively. The ternary PtNiCo alloys were evenly distributed on the supports of RGO–SO3H with size ranging from tens of nanometer in thickness and hundreds of nanometer in length. The electrocatalysis of PtNiCo/RGO–SO3H was superior to that of PtNiCo/RGO and PtNiCo/GO catalyst for ORR. The stability of PtNiCo/RGO–SO3H catalysts was characterized by the electrochemical surface area (ECSA) with 35% loss of the hydrogen adsorption/desorption after repeating 5000 cycles. The –SO3H groups grafted on RGO were in favor of ORR and anchoring site for PtNiCo nanoparticles. The high lattice contraction will support the retention of Ni and Co to enhance the catalyst activity in the ternary PtNiCo alloy. The synergistic effect of –SO3H groups and alloying elements can improve the catalytic efficiency and stability of PtNiCo/RGO–SO3H in the potential application of proton exchange membrane fuel cells.