Synthesis of free-standing ternary Rh-Pt-SnO2-carbon nanotube nanostructures as a highly active and robust catalyst for ethanol oxidation

The rational design of durable materials is an important issue for improving the performance of electrocatalysts towards the ethanol oxidation reaction (EOR). In this work, binderless thin nanostructured layers of SnO2, Pt, Rh, bilayers of Pt/SnO2, Rh/Pt and tri-layers of Rh (ca. 10 nm thickness)/PtSnO2 are directly grown by pulsed laser deposition onto carbon nanotubes (CNTs). SEM analysis shows that CNTs are perfectly coated with the catalysts. The onset potentials of the CO stripping and EOR indicate that Rh/Pt/SnO2 is the most active for the CO and the EOR. The incorporation of the CNTs in the catalyst layer is outstandingly beneficial to both the catalytic current activity and the durability. Indeed Rh/Pt/SnO2/CNT delivers mass activity as high as 213.42 mA mg-1 Pt. Moreover, Rh/Pt/SnO2/CNT demonstrates not only the lowest poisoning rate (by intermediate species, such as adsorbed CO) but also the highest durability current of 132.17 mA mg-1 Pt far superior to CNT-free Rh/Pt/SnO2/CP (58.33 mA mg-1 Pt). XPS shows that SnO2, Pt and Rh are all present at the surface of Rh/Pt/SnO2/CNT, the presence of two oxophilic materials like SnO2 and Rh, implies an earlier source of OHads-species, which facilitates the oxidation of CO and assuming a second contribution from Rh is to enhance the cleavage of the C-C bond for the complete oxidation of ethanol. The 3D porous and binderless structure, the low amount of the noble catalyst, the excellent electroactivity and durability of the Rh5/PtSnO2/CNT/CP composite represents an important step in advancing its use as an anode in commercial applications in DEFC.

Dual-Site Cascade Oxygen Reduction Mechanism on SnO x/Pt-Cu-Ni for Promoting Reaction Kinetics

Designing highly active oxygen reduction reaction (ORR) catalysts is crucial to boost the fuel cell economy. Previous research has mainly focused on Pt-based alloy catalysts in which surface Pt is the solely active site and the activity improvement was challenged by the discovered scaling relationship. Herein we report a new concept of utilizing dual active sites for the ORR and demonstrate its effectiveness by synthesizing a SnO _x/Pt-Cu-Ni heterojunctioned catalyst. A maximum of 40% enhancement in the apparent specific activity, which corresponds to 10-fold enhancement on interface sites, is measured compared with pure Pt-Cu-Ni. Detailed investigations suggest an altered dual-site cascade mechanism wherein the first two steps occur on SnO _x sites and the remaining steps occur on adjacent Pt sites, allowing a significant decrease in the energy barrier. This study with the suggested dual-site cascade mechanism shows the potential to overcome the ORR energy barrier bottleneck to develop highly active catalysts.

Effect of acid functionalised carbon supports for Pd–Ni–Sn catalyst on ethanol oxidation reaction

The reduction method was used to prepare catalysts on carbon black (CB), functionalised carbon black (CB_sn), multi-walled carbon nanotubes (MWCNTs) and functionalised MWCNTs (MWCNT_sn) to improve the catalytic activity for ethanol oxidation reaction.