PtCeO Heterojunction Supported on Multiwalled Carbon Nanotubes for Robust Electrocatalytic Oxidation of Methanol.

Herein, we prepared PtCeO heterojunction nanocluster (HJNS) on multiwalled carbon nanotubes (MWCNTs) in deep eutectic solvents (DESs) which is a special class of ionic liquids. The catalyst was then heat-treated at 400 °C in N (refer to PtCeO/CNTs-400). The PtCeO/CNTs-400 catalyst showed remarkably improved electrocatalytic performance towards methanol oxidation reaction (MOR) (839.1 mA mg) compared to PtCeO/CNTs-500 (620.3 mA mg), PtCeO/CNTs-300 (459.2 mA mg), PtCeO/CNTs (641.6 mAmg) (the catalyst which has not been heat-treated) and commercial Pt/C (229.9 mAmg). Additionally, the PtCeO/CNTs-400 catalyst also showed better CO poisoning resistance (onset potential: 0.47 V) compared to PtCeO/CNTs (0.56 V) and commercial Pt/C (0.58 V). The improved performance of PtCeO/CNTs-400 catalyst is attributed to the addition of appropriate CeO, which changed the electronic state around the Pt atoms, lowered the d-band of Pt atoms, formed more Ce-O-Pt bonds acting as new active sites, affected the adsorption of toxic intermediates and weakened the dissolution of Pt; on the other hand, with the assistance of thermal treatment at 400 °C, the obtained PtCeO HJNS expose more new active sites at the interface between Pt and CeO to enhance the electrochemical active surface area (ECSA) and the dehydrogenation process of MOR. Thirdly, DES is beneficial to the increase of the effective component Pt(0) in the carbonization process. The study shows a new way to construct high-performance Pt-CeO catalyst for the direct methanol fuel cell (DMFC).