Nanoporous Platinum Electrodes as Substrates for Metal Oxide-Supported Noble Metal Electrocatalytic Nanoparticles: Synergistic Effects During Electrooxidation of Ethanol

Abstract

Electrocatalytic oxidation of ethanol in acid medium (0.5 mol dm–3 H2SO4) was significantly enhanced by not only supporting bimetallic PtRu nanoparticles on nanostructured metal oxides (TiO2 or WO3), but also by depositing such catalytic systems on planar nanoporous platinized electrode substrates. Incorporation of TiO2 or WO3 into the electrocatalytic interface was likely to improve proton mobility and to provide –OH groups capable of inducing the removal of poisoning species, such as CO, from the Pt sites in the bimetallic PtRu catalyst. Synergistic interactions between ruthenium and titania were also possible. Regularly porous nanostructured platinum substrate also permitted development of submicro ‘reactors’ where reactant molecules, electrolyte ions, and all active components (TiO2 or WO3, Pt substrate, PtRu catalytic sites) could co-exist and become easily accessible. While WO3 was able to undergo fast reversible redox transitions to non-stoichiometric oxides, efficient utilization of inert (non-electroactive) TiO2 required admixing with carbon nanotubes to ensure easy charge distribution and good conductivity at the electrocatalytic interface.

Electroanalysis of Ethanol Oxidation and Reactivity of Platinum-Ruthenium Catalysts Supported onto Nanostructured Titanium Dioxide Matrices

“…To achieve this goal, 0.01 g of TiO 2 powder was weighed and subsequently dispersed in 1.25 cm 3 of deionized water using the ultrasonic bath. The suspension of TiO 2 (2 μdm 3 ) was next deposited onto surface of the glassy carbon disk electrode and, subsequently, dried in air at room temperature (22 • C) for 30 min. Multi-walled carbon nanotubes (CNTs) were prepared by dispersing 50 mg of them using ultrasonic bath in 5 cm 3 of deionized water.…”

“…4, 5 and 6) and literature reports, 22,24,[27][28][29][63][64][65][66] it can be rationalized that, at the potential as low 0.34 V, electrooxidation of ethanol at PtRu-based catalysts proceeds through simple dehydrogenation to acetaldehyde. 58,59 In other words, the reaction involves two-electrons, and no other parallel pathways (neither oxidation to acetic acid nor to carbon dioxide) are expected under potentials below 0.35 V. To comment on the dynamics of this reaction, we have performed diagnostic chronoamperometric experiments as for Fig.…”

“…9 Representative examples include studies with use of titanium(IV) oxide, [19][20][21][22] tungsten(VI) oxide [22][23][24][25] and zirconium(IV) oxide. [26][27][28][29] Any specific interactions between catalytic sites and the metal oxide matrix as well as the system's interfacial ion and electron transfer processes would be influenced by the distribution of electronic states within the oxide.…”

The 4th Molecular Materials Meeting (M3) @ Singapore

“…[27] In this brief highlight, the authors cover single-layer silicene to multilayer silicene, germanene, and stanene/tinene, as well as phosphorene, which are all highly popular in non-graphene 2D material research. In conclusion, it was stressed that these non-traditional 2D materials possess significant advantages over graphene-based materials in terms [23] of easier material transfer and integration. Some of them could be potentially used for quantum computing applications, thus promising a bright future for these materials.…”

“…In nanostructured materials preparation, Rutkowska et al (University of Warsaw, Poland) report on electrocatalytic metal oxidesupported noble metal nanoparticles on nanoporous platinum electrodes for electrooxidation of ethanol in which synergistic effects were observed. [23] The authors propose that the electrocatalytic activities were enhanced by the large population of hydroxyl groups on the surfaces of the nanostructured TiO 2 and WO 3 , where the -OH groups induced oxidation of CO passivating intermediates (on Pt) and increased the activity of the Ru component. It was further noted that WO 3 and TiO 2 would undergo different mechanisms, and the oxidation reaction of ethanol was typically more efficient at the nanoporous Pt substrate covered by WO 3 -supported PtRu than at the Pt substrate with TiO 2 -supported PtRu on the surface (Fig.…”