Changes in electronic structure of carbon supports for Pt catalysts induced by vacancy formation due to Ar irradiation

Okazaki, Hiroyuki*; Kakitani, Kenta*; Kimata, Tetsuya*; Idesaki, Akira*; Koshikawa, Hiroshi*; Matsumura, Daiju; Yamamoto, Shunya*; Yamaki, Tetsuya*

Journal of Chemical Physics, 152(12), p.124708_1 - 124708_5, 2020/03

https://doi.org/10.1063/1.5144568

Platinum nanoparticles on the glassy carbon surface irradiated with argon ions

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Kobayashi, Tomohiro*; Terai, Takayuki*

Surface & Coatings Technology, 306(Part A), p.123 - 126, 2016/11

https://doi.org/10.1016/j.surfcoat.2016.05.042

Platinum (Pt) nanoparticle catalysts with oxygen reduction reaction (ORR) activity are required for practical applications of polymer electrolyte fuel cells. We prepared Pt nanoparticles on an Ar-irradiated glassy carbon (GC) surface by a radio-frequency magnetron sputtering method to investigate the influence of the ion-induced lattice defects in GC on the ORR activity of the deposited Pt nanoparticles. Interestingly, the Pt nanoparticles on the irradiated surface exhibited ca. 2.5 times higher specific activity than those on the non-irradiated one. X-ray photoelectron spectroscopy suggested the interfacial Pt-C interaction occurring between the irradiated GC and Pt nanoparticles, which should be a reason for improvement of the ORR activity.

Oxygen reduction reaction activity of platinum nanoparticles on ion-irradiated glassy carbon substrate

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kobayashi, Tomohiro*; Terai, Takayuki*

no journal, , 

There have been intensive studies in the development of platinum (Pt) nanoparticle catalyst with high electrocatalytic activity and durability for fuel cell applications. We prepared the Pt nanoparticles on a glassy carbon (GC) substrate irradiated with 380 keV Ar, and then analyzed their electrocatalytic properties by a rotating disk electrode method. The Pt nanoparticles exhibited higher oxygen reduction reaction activity on the irradiated GC substrate than on the non-irradiated one. This suggests that the Ar-ion-induced modification of GC would improve the electrocatalytic properties of the deposited Pt nanoparticles.

Preparation of Pt nanoparticle catalysts on glassy carbon; Influence of the substrate irradiated with Ar ions

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*

no journal, , 

Platinum (Pt) nanoparticles prepared by Pt-ion implantation in a glassy carbon (GC) substrate exhibited high durability as oxygen reduction catalyst. This result would originate from chemical and electronic interaction between the Pt atoms at the particle surface and the lattice defects in the GC substrate introduced by the ion implantation. We prepared Pt nanoparticles by RF magnetron sputtering on the GC substrate modified by Ar-ion irradiation, and then investigated the influence of Ar-ion irradiation on their electronic structure. X-ray photoelectron spectroscopy demonstrated that the formation of the Pt-C bonding at the interface was promoted by the pre-deposition Ar-ion irradiation of the GC substrate.

Activity enhancement of Pt nanoparticle catalysts by the ion-irradiated carbon supports; Clarification of the interfacial structures by XAFS measurements

Kimata, Tetsuya*; Kakitani, Kenta*; Yamamoto, Shunya*; Taguchi, Tomitsugu*; Matsumura, Daiju; Shimoyama, Iwao; Iwase, Akihiro*; Kobayashi, Tomohiro*; Yamaki, Tetsuya*; Terai, Takayuki*

no journal, , 

Quite recently, the Pt nanoparticles on the Ar-ion-irradiated glassy carbon (GC) substrate have been found to exhibit high oxygen reduction reaction (ORR) activity due to electronic and structural effects through the irradiation lattice defects in the support. We performed X-ray absorption fine structure (XAFS) measurements to investigate the interface between GC and the Pt nanoparticles. The extended X-ray absorption fine structure at the Pt L edge demonstrated that the Pt-Pt bond length in the Pt nanoparticles was shorter on the Ar-ion-irradiated GC substrate than on the non-irradiated one. Therefore, the electronic interaction at the interface would modify the atomic structure of the supported Pt nanoparticles, thereby improving their ORR activity. This invited talk, called the JSAP young scientist presentation award speech, reviews what our strategy of the XAFS measurements should be for the mechanistic understanding of the GC/Pt-nanoparticle interface and enhanced ORR activity.

Local structure analysis of Pt nanoparticles on Ar-ion-irradiated glassy carbon substrate by XAFS measurements

Kimata, Tetsuya*; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Matsumura, Daiju; Shimoyama, Iwao; Iwase, Akihiro*; Fujimura, Yuki*; Kobayashi, Tomohiro*; Terai, Takayuki*

no journal, , 

Carbon-supported platinum (Pt) nanoparticles have been studied intensively for applications to oxygen reduction reaction (ORR) catalysts in polymer electrolyte fuel cells. The Pt nanoparticles on the Ar-ion-irradiated glassy carbon (GC) substrate were previously found to improve ORR activity. We analyzed here the local structure by XAFS measurements to clarify the mechanism of the Pt-C bonding at the Pt/GC interface, which could contribute to the observed high ORR activity. A decrease in the white-line intensity at Pt M and L edges suggests the reduction of the vacancy in the Pt 5d orbital, thereby leading to the interfacial structure with suppressed oxygen adsorbability.

Electrocatalytic properties of Pt nanoparticles on glassy carbon substrate pre-irradiated with Ar ions

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kobayashi, Tomohiro*; Terai, Takayuki*

no journal, , 

Platinum (Pt) nanoparticles having high activities for an oxygen reduction reaction have been studied intensively for applications to polymer electrolyte fuel cells. We prepared the Pt nanoparticles on a glassy carbon (GC) substrate irradiated with 380 keV Ar at the fluence of 1.010 ions/cm, and then analyzed their electrocatalytic properties by a rotating disk electrode method. The Pt nanoparticles on the Ar-ion-irradiated GC substrate exhibited ca. 2.5 times higher current density than those on the non-irradiated one. This striking result suggests that the Ar-ion-induced modification of the GC substrate would improve the electrocatalytic activities of the deposited Pt nanoparticles.

Improvement of Pt nanoparticle catalysts for fuel cell applications by ion irradiation; Influence of glassy carbon substrate irradiated with Ar ions

Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*

no journal, , 

Platinum (Pt) nanoparticles prepared by ion implantation in a glassy carbon (GC) substrate exhibited high activity and durability as oxygen reduction reaction (ORR) catalyst. This result would originate from chemical and electronic interaction between the Pt atoms at the particle surface and the lattice defects in the GC substrate introduced by the ion implantation. In this study, therefore, we sputtered Pt nanoparticles on the Ar-ion-irradiated GC substrate and then investigated their catalytic activity and electronic structure in terms of the effects of the irradiation defects in the substrate. The Ar-ion irradiation of the GC substrate was found to improve the ORR activity in an acid solution and to promote the formation of the Pt-C bonding at the interface.