Preparation of TaOx by Electrochemical Technique and Its Application to Electrocatalytic Oxygen Reduction

Here we demonstrate a new and simple technique for preparing a tantalum oxide (TaO_x)-based electrocatalyst at room temperature for oxygen reduction reaction (ORR) by electrochemical technique [1-4]. The Ta₂O₅ on the as-prepared deposits was reduced by electrolysis at potential of −0.6 V vs. Ag|AgCl|KCl(sat.) for 12 h generating a smoother and thinner layer of its reduced species (TaO_x) (Fig. 1). The treated TaO_x exhibits a high ORR activity in acidic and alkaline solutions as seen from a fairly high onset potential (0.87 V vs. RHE) in comparison with that (0.98 V) at a commercially available Pt/C catalyst. By rotating ring-disk electrode voltammetric measurements, it can be concluded that this oxide possesses an almost four-electron ORR electrocatalysis at potential above 0.8 V vs. RHE and a two-electron ORR becomes significant gradually as the potential is increased negatively. The obtained results demonstrate that the present “treated” TaO_x is expected as a promising electrocatalyst for ORR in PEMFCs even though its electrocatalytic performance needs to be improved significantly further to replace the Pt/C.   

 

 

 

Fig. 1 Schematic illustration of the electrochemical preparation of TaO_xelectrocatalyst for ORR.

 

 

Acknowledgement

The present research was financially supported by Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

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