Enhancement of Activity and Durability through Cr Doping of TiO₂ Supports in Pt Electrocatalysts for Oxygen Reduction Reactions

Abstract

A challenging issue in the commercialization of fuel cells is to improve the kinetics of the sluggish oxygen reduction reaction (ORR) and durability of the cathode electrocatalyst under corrosive ORR conditions. In this paper, we report a promising approach to address these two major issues by Cr doping of TiO2 supports in Pt‐based electrocatalysts. It was clearly revealed that Cr doping led to a marked enhancement of ORR kinetics, which was attributed to the compressive strain in the Pt lattice as well as the increased electronic conductivity of the Cr–TiO2 supports. Furthermore, Pt/Cr–TiO2 demonstrated a far superior durability to that of conventional Pt/C, which was assessed by accelerated durability tests (ADT) and in situ X‐ray absorption near‐edge structure studies. The specific activity of Pt/C decreased by 43 % after the ADT (141 μA cm−2 and 82 μA cm−2 before and after ADT, respectively), whereas that of Pt/Cr–TiO2 was merely reduced by 13 % (472 μA cm−2 and 409 μA cm−2).

Enhanced Oxygen Reduction Reaction Activity Due to Electronic Effects between Ag and Mn3O4 in Alkaline Media

“…In general, metal/metal oxide composites are known to exhibit strong metal support interactions (SMSIs), which induce a change in the ORR activity due to the strain effect. Most of the studies have focused on the SMSI of catalysts in acidic media (e.g., Pt/TiO 2 ). , Although various metal/metal oxide composites such as Pt/CaMnO 3 , Pd/TiO 2 , Pt/Ta 2 O 5 , Au/TiO 2 , and Ag/TiO 2 have been studied in the alkaline media, the change in the ORR activity has been mainly attributed to the synergetic effect. ,− Even though the electrochemical mechanism for the enhancement in the ORR activity has been analyzed in terms of the bifunctional effect, , few studies on the effect of the catalyst properties on the ORR activity in alkaline media have been carried out.…”

Unassisted photoelectrochemical hydrogen peroxide production over MoOx-supported Mo on a Cu3BiS3 photocathode

“…[14][15][16] Tuning the adsorption strength between transition metals and oxygen-based adsorbates is closely linked to the d-band energies of transition metals, which can be readily modified through metal/metal oxide heterostructures. [17][18][19] For example, Kim's group successfully optimized the d-band electron energies of Ag by placing it in contact with a transition metal oxide with a higher work function as the electron density is shifted towards metal oxide. 20 These upshifted d-band electron energies of Ag provided higher adsorption strength toward the oxygen-containing intermediate, thereby enhancing the ORR activity.…”

Highly Durable and Active Ternary Pt–Au–Ni Electrocatalyst for Oxygen Reduction Reaction

“…Although platinum (Pt) is the preferred cathode catalyst for ORR, the sluggish kinetics and low stability of Pt catalyst are the main obstacles for its extensive application in PEMFCs . Numerous efforts have been focused on synthesizing suitable alternative ORR catalysts that with low Pt loading, long‐term stability, and high activity, such as developing excellent catalyst supports, alloying Pt with other metals, designing the structures, and controlling the shapes of the catalysts . Alloying Pt with 3d transition metals (such as Pb, Co, Fe, and Ni) can not only reduce the usage of Pt metal but also improve its ORR activity .…”