High stability and high activity Pd/ITO-CNTs electrocatalyst for direct formic acid fuel cell

• Pd catalyst with ITO and CNTs as a mixture support for DFAFC was first prepared by microwave-assisted polyol process.
• The activity and stability of Pd/ITO-CNTs catalyst is significantly higher than those of Pd/CNTs.
• When ITO content is 50% of ITO/CNTs support mass, Pd/ITO-CNTs exhibits the best performance.

Indium tin oxide (ITO) and carbon nanotube hybrid has been explored as a support for Pd catalyst. Pd/ITO-CNTs catalysts with different ITO contents were prepared by the microwave-assisted polyol process. The as-prepared Pd/ITO-CNTs catalysts were characterized by X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and electrochemical measurements in this work. The TEM results show that Pd particle size distribution in the Pd/ITO-CNTs catalyst is more uniform than that in Pd/CNTs, indicating that the ITO can promote the dispersion of Pd nanoparticles. It is found that there is metal-support interaction between Pd nanoparticles and ITO in the Pd/ITO-CNTs catalyst through XPS test. The results of electrochemical tests prove that the Pd/ITO-CNTs catalysts exhibit higher electro-catalytic activity and stability than Pd/CNTs toward formic acid electrooxidation. When the ITO content is 50% of ITO-CNTs support mass, the Pd/ITO-CNTs catalyst has the best catalytic performance for formic acid electrooxidation. The peak current density of formic acid electrooxidation on the Pd/ITO-CNTs50% electrode is 1.53 times as high as that on Pd/CNTs, 2.31 times higher than that on Pd/ITO. The results of aging test show that the peak current density on the Pd/ITO-CNTs decreases by only 14.0%, while 56.1% on the Pd/CNTs after 500 cycles. It is due to the promoting effect of In2O3 and SnO2 in ITO, and metal-support interaction between Pd nanoparticles and ITO.

The addition of ITO in Pd/CNTs catalyst significantly improves the activity and stability of catalyst for formic acid electrooxidation due to excellent stability and high electrical conductivity of ITO, and metal-support interaction between Pd nanoparticles and ITO.Figure optionsDownload as PowerPoint slide