Platinum–rhodium–tin/carbon electrocatalysts for ethanol oxidation in acid media: effect of the precursor addition order and the amount of tin

Abstract

Carbon-supported Ptx-Rhy-Snz catalysts (x:y:z = 3:1:4, 6:2:4, 9:3:4) are prepared by Pt, Rh and Sn precursors reduction in different addition order. The materials are characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy techniques and are evaluated for the electrooxidation of ethanol in acidic media by cyclic voltammetry, chronoamperometry and anode potentiostatic polarization.. Oxidized Rh species prevail on the surface of catalysts synthetized by simultaneous co-precipitation, thus demonstrating the influence of synthesis method on the oxidation state of catalysts. Furthermore, high amounts of Sn in composites synthetized by co-precipitation results in very active catalysts at low potentials (bifunctional effect) while medium Sn load is needed for sequentially deposited catalysts when the electronic effect is most important (high potentials), since more exposed Pt and Rh sites are needed on the catalyst surface to alcohol oxidation. The Pt3-Rh1-Sn4/C catalyst prepared by coprecipitation is the most active at potentials lower than 0.55 V (related to bifunctional effect) while the Pt6-Rh2-Sn4/C catalyst, prepared by sequential precipitation (first Rh and, after drying, Pt+Sn), is the most active above 0.55 V.

Porous Trimetallic PtRhCu Cubic Nanoboxes for Ethanol Electrooxidation

“…In general, the electrocatalytic activity of the catalysts closely relates to their structure and chemical composition . PtRhCu CNBs have the trimetallic composition, enormous holes, and small nanocrystal subunits, which are expected to be an ideal electrocatalyst for the EOR . In order to explore the role of three elements for the electrocatalytic activity, a series of electrochemical measurements have been performed.…”

“…and that at Pt NPs-hm (1050 mA mg N −1 ), respectively, which is caused partly by high ECSA value of Pt 54 Rh 4 Cu 42 CNBs. [54] Based on the above results, we can safely conclude that the participation of Rh could effectively change the reaction pathway of the EOR. As observed, the EOR peak current density at Pt 54 Rh 4 Cu 42 CNBs (14.9 mA cm −2 ) is still 1.6 and 2.3 times higher than that at Pt 58 Cu 42 CNBs (8.7 mA cm −2 ) and Pt NPs-hm (6.5 mA cm −2 ), respectively.…”

“…The I f / I b of the EOR at Pt 54 Rh 4 Cu 42 CNBs (2.1) exhibits two times higher than that at Pt 58 Cu 42 CNBs (1.0) and Pt NPs‐hm (1.0), respectively. The large value of I f / I b implies the less poisoning intermediates in the course of the EOR . Based on the above results, we can safely conclude that the participation of Rh could effectively change the reaction pathway of the EOR.…”

“…The fine structure of Pt 54 www.advenergymat.de www.advancedsciencenews.com is ≈7.9 nm (Figure 3a). Herein, the shell thickness of CNBs is related to the amount of the noble metals precursors.…”

Methanol Electro-Oxidation on Carbon-Supported PtRu Nanowires

“…More information regarding the setup of the assembled electrochemical system is found elsewhere. 45 Substrates for the electro-catalytic materials were prepared using the procedure described by Salazar-Banda et al 46 The catalysts suspension was deposited onto de BDD substrate as described in a previous report. 47 Pt/C (10 wt% of Pt) and PtRu/C (20 wt% metal load with 80:20 Pt:Ru) from E-Tek commercial electro-catalysts were used as reference materials for comparison purposes.…”