Electroless plated Cu–Ni anode catalyst for natural gas solid oxide fuel cells

• Electroless plated Cu on Ni/YSZ slowed down the formation of graphitic carbon.
• Cu favored the formation of disordered carbon.
• Cu increased the ratio of anode activation polarization of CH4 to H2.

A Ni/YSZ anode and a Ni/YSZ modified by Cu electroless plating were investigated for direct utilization of CH4, the major component in natural gas. The catalytic activity of the anodes toward H2 and CH4 oxidation reactions were investigated by comparing the Faraday resistance, RF, of the cells obtained from impedance spectroscopy. The RF ratio of Cu–Ni/YSZ in CH4 to H2 was greater than that of Ni/YSZ, indicating low catalytic activity of Cu–Ni/YSZ anode toward CH4 oxidation. The addition of Cu to the Ni/YSZ anode decreased the catalytic activity, but increased the long-term stability of the anode in CH4 fuel. The Cu–Ni/YSZ anode showed long-term stability of 138 h in dry CH4 at 750 °C. The Raman spectra of the fuel cell cross-section showed a change in type of carbon as a function of Cu concentration. The Cu rich surface showed more disordered carbon as opposed to graphitic carbon on Cu deficient areas in which Cu concentration gradually decreased toward the interlayer. Graphitic carbon produced on highly active Ni surface is known as a precursor to coking. Thus, optimizing the distribution of Cu in the Ni/YSZ anode will be required to develop a stable and high performance anode catalyst for direct CH4 utilization.

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