Stabilizing nano-Pd on porous Li2TiO3via chemical and electrochemical reduction systems for the electrooxidation of ethylene glycol

Abstract

The challenge of breaking the C–C bond in ethylene glycol oxidation requires an efficient electrocatalyst. A porous oxide as the promoter boosts the dispersion of noble metal onto the electrocatalyst surface. Porous Li2TiO3 (LT) was synthesized, characterized, and applied as a promoter for palladium nanoparticles. The nano-Pd as a stable and efficient catalyst was stabilized on spinel LT promoter via two different reduction approaches including chemical (NaBH4) and electrochemical (Zn sheet/HCl) systems. Different techniques such X-ray diffraction, Fourier Transform Infrared Spectroscopy, Energy-Dispersive X-Ray Spectroscopy, Differential scanning calorimetry, thermogravimetric analysis, Barrett-Joyner-Halenda test, scanning electron microscopy, and transition electron microscopy were characterization of LT and LT/Pd. The size of the mesopores is between 2 and 19 nm. In comparison with non-promoted Pd, Pd/LT electrocatalyst was shown an excellent efficiency in parameters like electrochemical active surface area and anti-CO poisoning behaviour. The LT increases the removal of intermediates created in the oxidation of ethylene glycol that can poison the surface of Pd catalyst. This is due to the presence of the lattice oxygens in LT structure and Ti switching between its high and low valances. The morphology of as-synthesized electrocatalysts that was probed by FESEM micrographs demonstrates the embedment of nano-Pd onto the surface and into LT cavities. The results showed that the nano-Pd manufactured with the chemical reduction has a smaller size with high dispersion than the electrochemical reduction system. In this study, for the first time, the adsorption isotherms of fuel on the catalyst's surface were determined through the calculations of adsorption and desorption of hydrogen in the different concentrations of ethylene glycol.