Au@BICUVOX10 composite cathode for novel structure low-temperature solid-oxide fuel cells

Abstract

A composite Au@Bi 2Cu 0.1V 0.9O 5.35 (BICUVOX10) cathode is prepared and tested as a ceramal electrode for use in low-temperature solid-oxide fuel cells (SOFCs). Au powder is coated onto the surface of BICUVOX10 from an aqueous solution of the chloride with NaBH 4 as a reductant. The valence of the surface Au is identified as Au(0) by X-ray photoelectron spectroscopy (XPS). The BICUVOX10 substrate is synthesized from V 2O 3, CuO, and Bi 2O 3 and then investigated by field-emission scanning electron microscopy (SEM). The average size of the particles is estimated to be 100 nm after milling with a planetary ball-mill. The core–shell structure of Au@BICUVOX10 is confirmed by transmission electron microscopy (TEM). The two-dimensional coefficient of thermal expansion (CTE) and the conductivities of mixed powders with different proportions of Au is also tested from room temperature to 600 °C. A single fuel cell is fabricated with Au@BICUVOX10 as the cathode, NiO/GDC (Gd 0.1Ce 0.9O 1.95) as the supporting anode, and GDC as the electrolyte. The electrochemical performance is tested and the highest power densities of the fuel cell are determined to be 127, 206, 359, 469, and 474 mW cm −2 at 450, 500, 525, 550, and 575 °C, respectively. Finally, the stability of the single SOFC is tested, whereupon it is found that its output is maintained for at least the first 20 h.