TaOx-capped Pt nanoparticles as active and durable electrocatalysts for oxygen reduction

Abstract

Here we demonstrate the formation of unique structure of TaO_x-capped Pt nanoparticles on a Pt/TaO_x/GC electrocatalyst, where at first tantalum oxide (TaO_x) and next Pt nanoparticles were electrodeposited on the glassy carbon (GC) substrate, for an oxygen reduction reaction. The surface characterizations show that the nanoparticles of TaO_x deposit homogeneously on the GC surface, forming a thin layer and surprisingly, the Pt nanoparticles do not exactly deposit on the top layer of the TaO_x, i.e., Ta₂O₅ but inside their framework and consequently a unique assembly of the TaO_x-capped Pt particles is fabricated. The analyses using XPS spectra indicate electronic interactions of TaO_x with the GC, as well as with the Pt nanoparticles. The electrochemical measurements conducted by cyclic voltammetry and rotating ring-disk electrode voltammetry reveal that the novel electrocatalyst possesses an enhanced activity for an oxygen reduction reaction, without any loss of performance even after 250 000 cycles (1111 h) of a durability test. The plausible reasons for the remarkable activity and durability of this electrocatalyst are proposed.