Synthesis of conductive rutile-phased Nb0.06Ti0.94O2 and its supported Pt electrocatalysts (Pt/Nb0.06Ti0.94O2) for the oxygenreduction reaction

Abstract

In this paper, Nb-doped TiO₂ with anatase and rutile phases was synthesized by the acid-catalyzed sol–gel method, and used as catalyst supports for the oxygen reduction reaction (ORR). X-ray diffraction (XRD), transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET) were used to characterize the support materials in terms of material structures, morphology, composition, and surface area. XRD analysis showed that both the high concentration of hydrochloric acid present in the synthesis and the presence of Pt in the support could favor the formation of conductive rutile phased TiO₂, resulting in the improvement of electronic conduction of the Nb-doped TiO₂ support, which was confirmed by measured conductivities. For electrochemical characterization and ORR catalyst activity validation, Pt particles were deposited on the supports synthesized in this paper to form several catalysts, which were tested for electrochemical Pt surface area, ORR mass activity and specific activity. A monotonic increase in Pt ORR mass activity with increasing catalyst support’s conductivity suggested that the support conductivity plays an important role in enhancing catalyst mass activity. The results showed that these non-carbon supported catalysts are promising as PEM fuel cell cathode catalysts.