Enhancement of Catalytic Activity and Durability of Pt Nanoparticle through Strong Chemical Interaction with Electrically Conductive Support of Magnéli Phase Titanium Oxide

In this study, we address the catalytic performance of variously sized Pt nanoparticles (NPs) (from 1.7 to 2.9 nm) supported on magnéli phase titanium oxide (MPTO, Ti4O7) along with commercial solid type carbon (VXC-72R) for oxygen reduction reaction (ORR). Key idea is to utilize a robust and electrically conductive MPTO as a support material so that we employed it to improve the catalytic activity and durability through the strong metal-support interaction (SMSI). Furthermore, we increase the specific surface area of MPTO up to 61.6 m2 g−1 to enhance the SMSI effect between Pt NP and MPTO. After the deposition of a range of Pt NPs on the support materials, we investigate the ORR activity and durability using a rotating disk electrode (RDE) technique in acid media. As a result of accelerated stress test (AST) for 30k cycles, regardless of the Pt particle size, we confirmed that Pt/MPTO samples show a lower electrochemical surface area (ECSA) loss (<20%) than that of Pt/C (~40%). That is explained by the increased dissolution potential and binding energy of Pt on MPTO against to carbon, which is supported by the density functional theory (DFT) calculations. Based on these results, we found that conductive metal oxides could be an alternative as a support material for the long-term fuel cell operation.

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Employing Exfoliated Graphite as Novel Support Material for Heterogeneous Model Catalysts

10.26434/chemrxiv.8079620 ◽

2019 ◽

Author(s):

Moritz Wolf ◽

Nico Fischer ◽

Michael Claeys

Keyword(s):

Surface Area ◽

Graphite Powder ◽

Model Catalysts ◽

Model Systems ◽

Exfoliated Graphite ◽

Support Material ◽

Heterogeneous Model ◽

Support Materials ◽

Metal Support Interaction ◽

Catalyst Systems

The inert nature of graphitic samples allows for characterisation of rather isolated supported nanoparticles in model catalysts, as long as sufficiently large inter-particle distances are obtained. However, the low surface area of graphite and the little interaction with nanoparticles result in a challenging application of conventional preparation routes in practice. In the present study, a set of graphitic carbon materials was characterised in order to identify potential support materials for the preparation of model catalyst systems. Various sizes of well-defined Co3O4 nanoparticles were synthesised separately and supported onto exfoliated graphite powder, that is graphite after solvent-assisted exfoliation via ultrasonication resulting in thinner flakes with increased specific surface area. The developed model catalysts are ideally suited for sintering studies of isolated nano-sized cobaltous particles as the graphitic support material does not provide distinct metal-support interaction. Furthermore, the differently sized cobaltous particles in the various model systems render possible studies on structural dependencies of activity, selectivity, and deactivation in cobalt oxide or cobalt catalysed reactions.

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Employing Exfoliated Graphite as Novel Support Material for Heterogeneous Model Catalysts

10.26434/chemrxiv.8079620.v1 ◽

2019 ◽

Author(s):

Moritz Wolf ◽

Nico Fischer ◽

Michael Claeys

Keyword(s):

Surface Area ◽

Graphite Powder ◽

Model Catalysts ◽

Model Systems ◽

Exfoliated Graphite ◽

Support Material ◽

Heterogeneous Model ◽

Support Materials ◽

Metal Support Interaction ◽

Catalyst Systems

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Reduction in the Thermal Conductivity of Thermoelectric Titanium Oxide by Introduction of Planar Defects

MRS Proceedings ◽

10.1557/proc-1218-z01-04 ◽

2009 ◽

Vol 1218 ◽

Cited By ~ 1

Author(s):

Shunta Harada ◽

Katsushi Tanaka ◽

Haruyuki Inui

Keyword(s):

Thermal Conductivity ◽

Titanium Oxide ◽

Hot Pressing ◽

Oxygen Deficiency ◽

Nominal Composition ◽

Titanium Oxides ◽

X Ray Diffraction ◽

Planar Defects ◽

Magnéli Phase ◽

Magneli Phase

AbstractThermoelectric properties of a homologous series of Magnéli phase titanium oxides TinO2n-1 (n = 2, 3..) have been investigated. Dense polycrystalline specimens with nominal composition of TiO2-x (x = 0.10, 0.20) have been prepared by conventional hot-pressing. X-ray diffraction analysis has revealed that prepared specimens are slightly reduced during hot-pressing. Electrical conduction is of n-type for all prepared titanium oxides and electrical resistivity and absolute values of Seebeck coefficient decrease with increasing oxygen deficiency. The carrier concentration of Magnéli phase titanium oxide increases with increasing oxygen deficiency. Lattice thermal conductivity decreases with increasing oxygen deficiency by more than 60% at room temperature and 40% at 773K compared to TiO2, which can be due to the presence of dense planar defects. The largest thermoelectric figure of merit Z, 1.6×10-4 K-1 at 773K, was obtained in TiO1.90 hot pressed specimen.

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MnCo2O4 decorated Magnéli phase titanium oxide as a carbon-free cathode for Li–O2 batteries

Journal of Materials Chemistry A ◽

10.1039/c7ta06152h ◽

2017 ◽

Vol 5 (37) ◽

pp. 19991-19996 ◽

Cited By ~ 13

Author(s):

Xuecheng Cao ◽

Zhihui Sun ◽

Xiangjun Zheng ◽

Jinghua Tian ◽

Chao Jin ◽

...

Keyword(s):

Titanium Oxide ◽

Electrocatalytic Activity ◽

High Performance ◽

Electronic Conductivity ◽

Synergistic Interaction ◽

High Electronic Conductivity ◽

Magnéli Phase ◽

First Time ◽

Magneli Phase

The application of MnCo2O4 (MCO) decorated Ti4O7 as a carbon-free cathode for Li–O2 batteries is reported for the first time. The high performance of Ti4O7/MCO cathode is attributed to the high electronic conductivity of Ti4O7, the high electrocatalytic activity of MCO and the synergistic interaction between Ti4O7 and MCO toward ORR and OER.

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H2-TPR, XPS and TEM Study of the Reduction of Ru and Re promoted Co/γ-Al2O3, Co/TiO2 and Co/SiC Catalysts

Journal of Materials Science Research ◽

10.5539/jmsr.v5n2p39 ◽

2016 ◽

Vol 5 (2) ◽

pp. 39 ◽

Cited By ~ 3

Author(s):

H. Romar ◽

A. H. Lillebo ◽

P. Tynjala ◽

T. Hu ◽

A. Holmen ◽

...

Keyword(s):

Catalytic Activity ◽

Metallic Nanoparticles ◽

Surface Composition ◽

Active Phase ◽

Support Materials ◽

Metal Support Interaction ◽

Active Metal ◽

Metal Support ◽

Oxide Phases

Effects of Ru and Re promoters on Co-CoOx catalysts supported on γ-Al2O3, TiO2 and SiC were investigated to improve the understanding of the role of promoters of the active phase of Co-CoOx-Ru and Co-CoOx-Re. The influence of promoter addition on the composition and activity of the catalysts was characterized by several methods, such as H2-TPR, XPS, chemisorption and TEM. Furthermore, the role of support and metal-support interaction was especially studied and different support materials were compared.Based on the results, addition of promoter metals (Ru or Re) will most likely improve catalytic activity of Co/γ-Al2O3, Co/TiO2 and Co/SiC catalysts by increasing the active metal surface available for chemical reaction and by decreasing the size of the metallic nanoparticles. These changes in the catalytic activity were also associated with the changes in the ratio of metal and metal oxide phases in the surface composition as observed by XPS. Promoter metals also decreased the reduction temperatures needed for the reduction of Co3O4 to CoO and further to metallic cobalt. Significant decrease in reduction temperature was observed especially when ruthenium was used as the promoter.

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