Tetrahexahedral Pt Nanocrystal Catalysts Decorated with Ru Adatoms and Their Enhanced Activity in Methanol Electrooxidation

Abstract

Tetrahexahedral Pt nanocrystals (THH Pt NCs) bound by well-defined high index crystal planes offer exceptional electrocatalytic activity, owing to a high density of low-coordination surface Pt sites. We report, herein, on methanol electrooxidation at THH Pt NC electrodes studied by a combination of electrochemical techniques and in situ FTIR spectroscopy. Pure THH Pt NC surfaces readily facilitate the dissociative chemisorption of methanol leading to poisoning by strongly adsorbed CO. Decoration of the stepped surfaces by Ru adatoms increases the tolerance to poisoning and thereby reduces the onset potential for methanol oxidation by over 100 mV. The Ru modified THH Pt NCs exhibit greatly superior catalytic currents and CO2 yields in the low potential range, when compared with a commercial PtRu alloy nanoparticle catalyst. These results are of fundamental importance in terms of model nanoparticle electrocatalytic systems of stepped surfaces and also have practical significance in the development of surface tailored, direct methanol fuel cell catalysts.NSFC [21021002, 20933004, 21073152, 20873113]; Fundamental Research Funds for the Central Universities [2010121021]; Program for New Century Excellent Talents in University; Queen's University Belfast (The ISW DEL Clean Energies); EPSRC [EP/I013229/1

The Use of C-MnO2 as Hybrid Precursor Support for a Pt/C-MnxO1+x Catalyst with Enhanced Activity for the Methanol Oxidation Reaction (MOR)

“…The electrochemical active surface area (ECSA) resulted 44.1 m 2 ·g −1 for Pt/C-MnxO1+x and 45.4 m 2 ·g −1 for Pt/C, respectively. For the PtRu/C catalyst the peak shape is different from the previous ones, with a sharper hydrogen desorption peak typical for the PtRu based catalysts [30,31] and ECSA of 69.8 m 2 ·g −1 . Regarding the Pt oxides reduction peak, for the Pt/C-MnxO1+x it is shifted towards more positive potentials of about 100 mV in comparison with the commercial Pt/C catalyst.…”

In-situ FTIR spectroscopic studies of electrocatalytic reactions and processes

“…In addition, the promotion effect on Pt-Ru alloy surface was also reported by Markovic et al[50]. Likewise, through decorating the tetrahexahedral Pt nanocrystal with Ru, the methanol oxidation activity is dramatically boosted[4]. FTIR spectra recorded in 1.0 M CH 3 OH + 0.1 M HClO 4 are presented respectively inFig.3a-d, for the clean THH NC electrode, THH NC electrodes with θ Ru of 0.30 and 0.49, and for the commercial carbon supported 1:1…”

“…Electrocatalyst plays a core role in energy conversion and storage, especially in the direct organic fuel cells (DOFCs) [4,5] and lithium air batteries. The DOFCs convert directly chemical energy inside small organic molecules (SOMs) into electrical energy, with the release of water and CO 2 .…”

Electrochemistry of Nanoparticles

“…These NPs then underwent dissolution/reprecipitation cycles to form tetrahexahedral NPs of 20-220 nm size with 24 {hk0} facets (Figure 8 c). [270] Although the use of tailored, preferentially shaped NPs (either enclosed by basal planes or by high index facets) is a seemingly straightforward approach to boost the catalytic activity for some reactions, such NPs are quite large (typically > 10 nm for basal plane faceted NPs and 20-150 nm for highindex NPs) compared to commercial catalysts (2-4 nm). [257] NPs prepared by this method have been employed for a variety of electrocatalytic reactions which are known to be promoted by defects and other low-coordination sites (ethanol oxidation on Pt [94,262,264] or Pd, [261,264,265] formic acid oxidation [94] and nitric oxide reduction on Pt, [266] and nitrite reduction on Fe).…”