Electronic effect in intermetallic electrocatalysts with low susceptibility to CO poisoning during hydrogen oxidation

Abstract

This paper reports the results of Hydrogen Oxidation Reaction (HOR) experiments over ordered intermetallic (PtSn and PdSn) nanoparticles under CO-free and CO-covered surface conditions. The activity of PtSn toward the HOR was comparable to the activity of commercially available Pt/C. In addition, PtSn/C presented low susceptibility to CO poisoning. In the case of CO-covered surfaces, it was found that the CO was weakly adsorbed at the surface of the PtSn nanoparticles and it did not inhibit the HOR; in fact, this catalyst performed better than Pt/C under the same experimental conditions. X-Ray Absorption assays conducted in the present work proved that the ability of Sn to donate electrons to the Pt adsorption sites was crucial for the resulting intermetallic catalyst to display high activity in the HOR and low susceptibility to CO poisoning.

Ordered PtSn/C Electrocatalyst: A High Performance Material for the Borohydride Electrooxidation Reaction

“…This outstanding performance of the PtSn/C material may be attributed to the unique electronic condition of the Pt adsorption surface site caused by the electron donor effect provided by the Sn atoms in the hexagonal geometric structure [29].…”

“…The as-prepared surface was submitted to electrochemical studies. Characterization of the electrode material was performed by X-ray Diffraction, Electron Dispersive Spectroscopy, and Transmission Electron Microscopy ( Figures S1, S2 and Table S1) [29].…”

Ethylene Oxidation in an Oxygen‐Deficient Environment: Why Ceria is an Active Support?

“…A positive percentage value indicates that less CO 2 was produced than theoretically possible; therefore, the observed peak is less likely caused by carbon deposition but rather adsorbed CO 2 from the oxidation of ethylene is desorbed. It has been well studied, especially for fuel cells, that Pt is poisoned by carbonaceous species, specifically CO, which therefore, explains the higher deposition of carbon on the Pt catalysts . The similar behaviour between Ir/CeO 2 and Ru/CeO 2 could be because they form oxides more readily than Pt, which allows a lower deposition of carbon as the surface is already covered by oxygen species …”

Carbon Monoxide Tolerant Pt-Based Electrocatalysts for H2-PEMFC Applications: Current Progress and Challenges

“…An electronic effect was rejected by the authors, because as stated the metallic Sn cannot introduce influential electronic modifications to Pt; however, previous studies do not agree on this point. It has been proposed that when Sn is alloyed with Pt, electron donation occurs from the Sn orbital to Pt orbital, leading to a downshift of the Pt d-band center and weakened CO adsorption [85,86]; therefore, an electronic effect should not be disregarded. It is also noted that in the absence of CO, Pt-Ru-Sn/C presented a lower cell potential than Pt-Ru/C and lower HOR activity (Figure 4h).…”