Pt/porous-IrO2 nanocomposite as promising electrocatalyst for unitized regenerative fuel cell

Pt/porous-IrO2 composite as bifunctional oxygen electrocatalyst for unitized regenerative fuel cell has been prepared by chemical reduction of Pt on porous IrO2 which is obtained via template-removal method. X-ray diffraction and transmission electron microscopy characterizations indicate that the Pt nanoparticles (ca. 4.4 nm) are deposited on both internal and external sites of porous IrO2 nanoparticles. Electrochemical analyses show that the activity toward oxygen evolution reaction on Pt/porous-IrO2 catalyst is 28% (at 1.55 V) higher than that on Pt/commercial-IrO2 catalyst, and the activity towards oxygen reduction reaction on the former is 2.3 times (at 0.85 V) that on the latter. Oxygen reduction on Pt/porous-IrO2 catalyst follows the first-order kinetics and the four-electron mechanism.

Porous IrO2 provides internal and external sites for Pt deposition and facilitates Pt dispersion and mass transport.Figure optionsDownload as PowerPoint slideHighlights
► Porous Pt/IrO2 as bifunctional oxygen electrocatalyst is prepared by depositing Pt on porous IrO2.
► Porous IrO2 is obtained via template-removal method and can provide internal and external sites for Pt deposition.
► Pt/porous-IrO2 catalyst exhibits high OER activity and excellent ORR activity in comparison with Pt/commercial-IrO2 catalyst.
► Oxygen reduction reaction on Pt/porous-IrO2 catalyst follows the first-order kinetics and the four-electron mechanism.