JP7599183B2 - Support - Google Patents

Description

This disclosure relates to a carrier and a method for manufacturing the carrier.

Platinum (Pt) is widely used as an electrode catalyst for fuel cells. However, Pt is a very expensive precious metal. Moreover, Pt reserves are insufficient. Therefore, in order to reduce the cost of fuel cells and to realize the widespread use of fuel cells, it is important to improve the catalytic activity and reduce the amount of Pt used.
A technique has been disclosed in which Pt nanoparticles or the like encapsulated in a specific dendrimer (dendritic polymer) are supported on a porous carbon material and used as a catalyst (see Patent Document 1).

JP 2013-159588 A

However, the supports obtained by the above techniques have the following three disadvantages from an industrial perspective.
That is,
(1) The synthesis of dendrimers requires various reagents (including organic solvents), which is industrially disadvantageous.
(2) In the first place, mass production technology for dendrimers has not yet been established.
(3) A separate step of combining the synthesized Pt particles with a carbon material is required, which is complicated.
The present disclosure has been made in view of the above-mentioned circumstances, and aims to provide a support in which clusters are supported on a support, which can be mass-produced industrially. The present invention is expected to be applied in a wide range of fields.
The present disclosure can be realized in the following forms.

[1] A support having clusters of an alloy containing Pt and Ni supported on a support,
A support having a Pt loading of 1×10 ⁻¹⁴ ng/cm ² or more and 1×10 ⁵ ng/cm ² or less.

[2] The carrier according to [1], wherein the carrier is made of a conductive material.

[3] The support according to [1] or [2], wherein the composition of the cluster is one or more selected from the group consisting of Pt ₃ Ni, Pt ₄ Ni, Pt ₆ Ni, and Pt ₆ Ni ₂ .

[4] A method for producing the support according to any one of [1] to [3],
A generating step of generating the clusters;
a supporting step of landing the clusters on the carrier and supporting the clusters;
The method for producing a support comprising the steps of:

[5] A selection step of selecting specific mass clusters having a mass within a specific range from the clusters,
The method for producing a support according to [4], wherein in the supporting step, the specific mass clusters are landed on the support.

The support of the present disclosure can be produced relatively easily and therefore can be mass-produced industrially.
The method for producing the support of the present disclosure is easier than conventional methods and is suitable for industrial mass production.

The present disclosure is further explained in the following detailed description, giving non-limiting examples of exemplary embodiments according to the invention, with reference to the mentioned drawings, in which:
FIG. 1 is a conceptual diagram showing an example of an apparatus for carrying out a method for producing a cluster support.

The matters set forth herein are illustrative and are intended to provide an illustrative description of the embodiments of the present invention, with the objective of providing what is believed to be the most effective and easily understood explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to provide structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some forms of the present invention may be embodied in practice.

The present disclosure is described in detail below. In this specification, when a numerical range is described using "to" it is intended to include the lower limit and the upper limit unless otherwise specified. For example, the description "10 to 20" is intended to include both the lower limit "10" and the upper limit "20". In other words, "10 to 20" has the same meaning as "10 or more and 20 or less".

1. Support The support is made by supporting clusters of an alloy containing Pt and Ni on a carrier. The amount of Pt supported is 1×10 ⁻¹⁴ ng/cm ² or more and 1×10 ⁵ ng/cm ² or less.

(1) Elements Constituting the Cluster From the viewpoint of practicality, the cluster is made of an alloy containing Pt (platinum) and Ni (nickel). The alloy may contain elements other than Pt and Ni that can constitute a conductive material. Suitable examples of the other elements include one or more elements selected from the group consisting of Au (gold), Ag (silver), Pd (palladium), Si (silicon), Ge (germanium), Sn (tin), In (indium), Cd (cadmium), Zn (zinc), W (tungsten), Ta (tantalum), Cu (copper), Ru (ruthenium), Co (cobalt), Ir (iridium), Cr (chromium), Fe (iron), V (vanadium), Mn (manganese), Y (yttrium), Tc (technetium), Ga (gallium), Nb (niobium), Mo (molybdenum), Zr (zirconium), Rh (rhodium), Os (osmium), Re (rhenium), Al (aluminum), and Ti (titanium).

(2) Composition of the cluster The composition of the cluster is not particularly limited as long as it contains Pt (platinum) and Ni (nickel). From the viewpoint of high mass activity, the composition of the cluster is preferably one or more selected from the group consisting of Pt ₃ Ni, Pt ₄ Ni, Pt ₆ Ni, and Pt ₆ Ni ₂ .
The cluster in the present disclosure is a nanocluster or sub-nanocluster. The form of the cluster is not particularly limited, but may be, for example, a form in which Pt atoms and Ni atoms are assembled in a ratio according to the above composition.

(3) Amount of Pt (platinum) supported The amount of Pt supported is 1×10 ⁻¹⁴ ng/cm ² or more and 1×10 ⁵ ng/cm ² or less. When the amount supported is within this range, the activity tends to be high when the support is used as a catalyst. It is presumed that the reason for the high mass activity when the amount of Pt (platinum) supported is 1×10 ⁻¹⁴ ng/cm ² or more and 1×10 ⁵ ng/cm ² or less is due to the contribution of the increase in the specific surface area due to the small size. Note that "mass activity" means mass activity (oxygen reduction current density per 1 g of Pt) for oxygen reduction reaction (ORR) (the same applies below).

(4) Mass Activity The mass activity of the support in which the alloy clusters are supported on a support is preferably greater than 200 A/g, more preferably 300 A/g or more, and even more preferably 400 A/g or more. The upper limit of the mass activity is usually 2×10 ⁴ A/g.
When the mass activity is in this range, the catalyst is useful as an electrode catalyst for a fuel electrode or the like.

(5) Support The support is not particularly limited. For example, carbon, titanium oxide, bismuth tellurium, bismuth selenium, aluminum, constantan, gold, silver, copper, brass, platinum, nichrome, iron, titanium, tungsten, tungsten oxide, indium tin oxide, strontium titanate, molybdenum, zinc, nickel, tin, lead, silicon, silicon carbide, stainless steel, magnesium, cobalt, lithium, chromium, manganin, polyaniline, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) [PEDOT/PSS], polyacetylene, polythiophene, polypyrrole, polyphenylenevinylene, polythienylenevinylene, ionic liquid, etc. are exemplified. In addition, among these examples, those that can be doped with other elements also include those doped with other elements.

2. Method for Producing the Support The method for producing the support is not particularly limited. Here, a preferred method for producing the support will be described.
The method for producing the support includes a generating step of generating clusters, and a supporting step of landing the clusters on a support and supporting the clusters.

(1) Generation process In the generation process, there is no particular limitation as long as it is a generation method that generates (generates) clusters, and a wide variety of methods can be used. For example, magnetron sputtering, ion sputtering, ion beam sputtering, laser evaporation, etc. can be used. Among these, magnetron sputtering is preferably used from the viewpoint of the amount of ions and their stability.
From the viewpoint of efficient catalytic reaction, the clusters generated in the generating step preferably have an atomic number of 2 or more and 100 or less, more preferably 3 or more and 80 or less.

The elements constituting the cluster ions include at least Pt (platinum) and Ni (nickel). Other elements constituting the cluster ions may include elements that can form a conductive material. The other elements preferably have a conductive property as a target in the DC magnetron sputtering method, and suitable examples thereof include one or more elements selected from the group consisting of Au (gold), Ag (silver), Pd (palladium), Si (silicon), Ge (germanium), Sn (tin), In (indium), Cd (cadmium), Zn (zinc), W (tungsten), Ta (tantalum), Cu (copper), Ru (ruthenium), Co (cobalt), Ir (iridium), Cr (chromium), Fe (iron), V (vanadium), Mn (manganese), Y (yttrium), Tc (technetium), Ga (gallium), Nb (niobium), Mo (molybdenum), Zr (zirconium), Rh (rhodium), Os (osmium), Re (rhenium), Al (aluminum), and Ti (titanium). In addition, with the laser vaporization method and the radio-frequency magnetron sputtering method, it is possible to generate cluster ions regardless of whether the target is conductive or not.

(2) Supporting Step In the supporting step, the clusters are landed on a carrier and supported thereon.
Regarding the carrier for carrying the clusters, the description in "1. (5) Carrier" above can be applied as is.
The landing of the clusters on the support is performed by a so-called soft landing. That is, the collision energy is preferably 1 eV/atom or less. By performing the soft landing of the clusters in this way, the destruction of the clusters can be suppressed.

(3) Other steps The method for producing a support may include a selection step for selecting specific mass clusters having a mass within a specific range from among the clusters. By including the selection step, the specific mass clusters land on the carrier. This selection step allows the specific mass clusters to be supported on the support, improving the utility value of the support.

The selection process is not particularly limited. It is preferable that the selection process uses an ion deflector and a quadrupole mass analyzer. The ion deflector can be used to select ions of a specific charge state, and the quadrupole mass analyzer can be used to further select clusters of a specific size.

(4) An Example of an Apparatus for Carrying Out the Manufacturing Method of a Cluster Support Here, an example of an apparatus 7 for manufacturing a cluster support for carrying out the above manufacturing method will be described (FIG. 1).
The cluster support manufacturing apparatus 7 includes a cluster generating apparatus 10. The cluster generating apparatus 10 includes a chamber 11 that is evacuated, a cluster growth cell 12 installed in the chamber 11, and a sputtering source 13 (magnetron sputtering source) installed in the cluster growth cell 12. The cluster growth cell 12 is surrounded by a liquid nitrogen jacket 14, and liquid nitrogen (N ₂ ) is configured to circulate through the liquid nitrogen jacket 14. The cluster generating apparatus 10 further includes a control device 15 and a pulsed power supply 16 for the sputtering source as components of a control system.

The cluster generating device 10 includes a first inert gas supply pipe 17 and a second inert gas supply pipe 18. The first inert gas supply pipe 17 supplies a first inert gas (e.g., argon gas (Ar)) for generating plasma to the sputtering source 13. The second inert gas supply pipe 18 supplies a second inert gas (e.g., helium gas (He)) into the cluster growth cell 12 for cooling and agglomerating metal atoms and metal ions generated from the sputtering source 13 and growing them as clusters. The main part of the second inert gas supply pipe 18 is stored in the liquid nitrogen jacket 14, and it spirally circles inside the liquid nitrogen jacket 14, with its end protruding into the inside of the cluster growth cell 12.

In this way, the second inert gas, such as helium, cooled by liquid nitrogen can be introduced into the cluster growth cell 12. The pressure inside the cluster growth cell 12 is maintained at about 10 to 40 Pa. Note that devices such as a pressure gauge provided in the cluster growth cell 12 for pressure control and a mass flow controller provided in the gas supply system are not shown in the figure.
The cluster generating apparatus 10 further includes an exhaust device 19 consisting of a turbo molecular pump or the like, and the inside of the chamber 11 is evacuated to a predetermined vacuum level (for example, 10 ⁻¹ to 10 ⁻⁴ Pa) by this exhaust device 19 .

The sputtering source 13 is composed of a target 131, an anode 132, and a magnet unit 133, and the target 131 is connected to the sputtering source pulse power supply 16 as a cathode. Ar gas is supplied into the cluster growth cell 12 from the first inert gas supply pipe 17, and pulsed power is supplied from the sputtering source pulse power supply 16, causing a glow discharge between the target 131 and the anode 132. That is, a high voltage is applied between the target 131 and the anode 132 in a pulsed manner, causing a glow discharge between the target 131 and the anode 132. In addition, by applying a magnetic field near the surface of the target 131 by the magnet unit 133, the cluster generation device 10 of this embodiment can perform magnetron sputtering and generate an even stronger glow discharge.

The tip of the first inert gas supply pipe 17 is configured to inject the first inert gas from one or more locations between the target 131 and the anode 132 of the sputtering source 13. However, the present invention is not limited to such a configuration, and any configuration can be adopted as long as the first inert gas can be supplied toward the target 131.
The sputtering source 13 is accommodated in the cluster growth cell 12 so as to be movable in the tube axial direction. This defines the extension distance of the cluster growth region in the tube axial direction. The extension distance in the tube axial direction means the growth region length, i.e., the distance from the surface of the target 131 to the beam outlet 121.

To generate clusters, a second inert gas cooled to liquid nitrogen temperature is introduced into the cluster growth cell 12, and a first inert gas is supplied to the sputtering source 13 while pulsed power is supplied from the sputtering source pulsed power supply 16. When pulsed power is supplied, sputter particles such as neutral atoms and ions derived from the target 131 are emitted as a group from the target 131 into the second inert gas.

This cluster is released at intervals equal to the repetition frequency of the pulsed power applied to the sputtering source 13 and moves along the flow of the second inert gas. At this time, the sputtered particles, such as neutral atoms and ions, that make up the cluster combine with each other in the second inert gas to generate clusters of various sizes. The generated clusters pass through the beam outlet 121 of the cluster growth cell 12 and then enter a downstream ion detection device, etc.

The ion detection device 20 has an ion guide electrode 21 located near the outer side of the beam outlet 121 of the cluster growth cell 12, thereby guiding the cluster ions emitted from the beam outlet 121 of the cluster growth cell 12. As shown in FIG. 1, the ion detection device 20 has a quadrupole ion deflector 22 provided on the beam outlet side of the ion guide electrode 21. The quadrupole ion deflector 22 deflects and extracts only the positive ions or negative ions in the clusters.

The ion detection device 20 has a quadrupole mass spectrometer 23 that analyzes the mass of the extracted clusters, extracts only clusters of a specific mass, and measures the amount of clusters produced by an ion detector 24 (picoammeter) to which a bias can be applied. For example, a current of 100 pA measured by the ion detector 24 corresponds to a cluster amount of 0.6 x ¹⁰⁹ clusters/sec (=1 fmol/sec). A carrier can be placed on the ion detector 24, and only clusters of a specific mass can be deposited on the carrier.

3. Advantages of the Present Embodiment The support of the present embodiment can be manufactured relatively easily, and therefore can be mass-produced industrially.
The method for producing the support of this embodiment is easier than the conventional method using a dendrimer, and is suitable for industrial mass production.

The following provides a more detailed explanation using examples.

1. Method for producing and evaluating a cluster support A cluster support was produced using the cluster support production apparatus 7 shown in FIG.
In detail, clusters of an alloy containing Pt and Ni were generated by magnetron sputtering using the cluster generation device 10. The device specifications and experimental parameters are as follows.

Sputter source: Angstrom Sciences ONYX-2
Pulse power supply: Zpulser AXIA-150
Target: Pt-Ni alloy (diameter 2 inches, purity 99.9% or higher)
Ar gas flow rate: 40-200 sccm
He gas flow rate: 60-400 sccm
Pressure in growth cell: 10-40 Pa
Growth cell inner diameter: 110 mm
Growth area length: 190-290mm
Beam extraction aperture: 12 mm

The alloy clusters were sorted by a specific charge state using a quadrupole ion deflector 22, and by size using a quadrupole mass spectrometer 23. The alloy cluster ions were then landed on a glassy carbon electrode (corresponding to the carrier of the present invention). The electrode had a diameter of 5 mm. The glassy carbon electrode was polished on a buff using an alumina suspension (particle size 0.05 μm), and after polishing, it was cleaned by irradiating it with ultrasonic waves in ultrapure water and quickly introduced into a vacuum chamber to support the alloy clusters. The amount of support was calculated from the current value measured by the ion detector 20. The mass activity (catalytic activity) of the clusters in the cluster support was evaluated using a rotating disk electrode (RDE (rotating disk electrode)).

2. Evaluation Results The results when alloy clusters were supported are shown in Tables 1 and 2. The supported amount (ng-Pt/cm ² ) means the amount of Pt supported in the alloy supported on the support.
From the results in Tables 1 and 2, the mass activity of any of the compositions was significantly higher than that of the standard catalyst (TEC10E50E: Tanaka Kikinzoku Kogyo Co., Ltd.), which has a mass activity of 299 A/g. This is presumably due to the contribution of an increase in the specific surface area caused by the smaller size of the clusters. Furthermore, in any of the compositions, the cluster support can be manufactured by a cluster support manufacturing apparatus 7 using a magnetron sputtering method, which allows for mass production that is more advantageous on an industrial scale than when dendrimers are used.

The foregoing examples are merely illustrative and are not to be construed as limiting the invention. While the invention has been described with reference to exemplary embodiments, it is understood that the words used in describing and illustrating the invention are descriptive and exemplary rather than limiting. As detailed herein, changes may be made within the scope of the appended claims without departing from the scope or spirit of the invention in its form. While the description of the invention has been made with reference to specific structures, materials and examples, it is not intended that the invention be limited to those disclosed herein, but rather that the invention extends to all functionally equivalent structures, methods and uses within the scope of the appended claims.

This disclosure is not limited to the embodiments detailed above, and various modifications and variations are possible within the scope of the claims of this disclosure.

The support of the present disclosure can be used in a wide range of applications in a wide range of technical fields. For example, the support of the present disclosure can be suitably used as a fuel cell electrode catalyst, an organic synthesis reaction catalyst, an exhaust gas catalyst, etc. The support of the present disclosure has high catalytic activity, so the amount of Pt used can be reduced, and since it can be mass-produced, it has a high cost reduction effect and can be widely used.

Reference Signs List 7 ...Cluster support manufacturing apparatus 10 ...Cluster generation apparatus 11 ...Chamber 12 ...Cluster growth cell 13 ...Sputtering source 14 ...Liquid nitrogen jacket 15 ...Control device 16 ...Pulse power supply for sputtering source 17 ...First inert gas supply pipe 18 ...Second inert gas supply pipe 19 ...Exhaust device 20 ...Ion detection device 21 ...Ion guide electrode 22 ...Quadrupole ion deflector 23 ...Quadrupole mass spectrometer 24 ...Ion detector 121 ...Beam outlet 131 ...Target 132 ...Anode 133 ...Magnet unit

Claims (1)

A support having one or more clusters selected from the group consisting of Pt ₃ Ni, Pt ₄ Ni, Pt ₆ Ni, and Pt ₆ Ni ₂ supported on a support,
The amount of Pt supported is 1×10 ⁻¹⁴ ng/cm ² or more and 1×10 ⁵ ng/cm ² or less ,
The carrier is made of a conductive material .

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