Pt 2 CeO 2 Heterojunction Supported on Multiwalled Carbon Nanotubes for Robust Electrocatalytic Oxidation of Methanol.

Herein, we prepared Pt 2 CeO 2 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 2 (refer to Pt 2 CeO 2 /CNTs-400). The Pt 2 CeO 2 /CNTs-400 catalyst showed remarkably improved electrocatalytic performance towards methanol oxidation reaction (MOR) (839.1 mA mg Pt -1 ) compared to Pt 2 CeO 2 /CNTs-500 (620.3 mA mg Pt -1 ), Pt 2 CeO 2 /CNTs-300 (459.2 mA mg Pt -1 ), Pt 2 CeO 2 /CNTs (641.6 mAmg -1 ) (the catalyst which has not been heat-treated) and commercial Pt/C (229.9 mAmg -1 ). Additionally, the Pt 2 CeO 2 /CNTs-400 catalyst also showed better CO poisoning resistance (onset potential: 0.47 V) compared to Pt 2 CeO 2 /CNTs (0.56 V) and commercial Pt/C (0.58 V). The improved performance of Pt 2 CeO 2 /CNTs-400 catalyst is attributed to the addition of appropriate CeO 2 , 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 Pt 2 CeO 2 HJNS expose more new active sites at the interface between Pt and CeO 2 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 2 catalyst for the direct methanol fuel cell (DMFC).