Development of durable carbon black/titanium dioxide supported macrocycle catalysts for oxygen reduction reaction

Abstract Carbon black and titanium dioxide supported iron tetraphenylporphyrin (FeTPP/TiO 2 /C) catalysts for oxygen reduction reaction (ORR) were prepared by sol–gel and precipitation methods followed by a heat-treatment at temperatures of 400–1000 °C. The FeTPP/C and TiO 2 /C were also studied for comparison. The FeTPP/TiO 2 /C pyrolyzed at 700 °C exhibits significantly improved stability while maintaining high activity towards ORR in comparison with the FeTPP/C counterpart. The electrochemical study combined with XRD, XPS, and SEM/EDX analyses revealed that the appropriate dispersion of TiO 2 on the surface of FeTPP/TiO 2 /C catalysts, which depending on heat-treatment temperature, plays a crucial role in determining the activity and stability of catalysts.