DETAILED ACTION
Application 18/184409, “CATALYST LAYER”, was filed with the USPTO on 3/15/23 and claims priority from a foreign application filed on 3/22/22.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
This Office Action on the merits is in response to communication filed on 12/30/25.
Terminal Disclaimer
The terminal disclaimer filed on 7/16/26 disclaiming the terminal portion of any patent granted on this application which would extend beyond the expiration date of USP 12,304,830 has been reviewed and is accepted. The terminal disclaimer has been recorded.
Claim Interpretation
Claims 1 and 12 each recite, “…tin oxide-based particles having a structure (connected structure) in which porous primary particles composed of an assembly of fine crystallites are connected to each other…”
Although “connected structure” is contained in parenthesis, this feature is interpreted to be required of the claimed invention rather than being optional. See Response to Arguments section below regarding the broadest reasonable interpretation of “connected structure”.
Allowable Subject Matter
Claim 12 was marked in the 4/16/26 Final Rejection as being allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims, and the obviousness-type double patenting rejection were overcome.
Claim 12 has now been written in independent form and a Terminal Disclaimer over USP 12,304,830 has been filed and accepted. Therefore, claim 12 is allowed.
The following is a copy of the examiner’s statement of reasons for allowance contained in the 4/16/26 Final Rejection:
Regarding dependent claim 12, the closest prior art includes Tsukuda (US 2017/0279143), which is applied in the art rejections herein, and Kakinuma (US 2017/0250409), which was applied in the art rejections of the 10/1/25 Non-Final Rejection.
As described herein, Tsukuda teaches a catalyst layer comprising tin-oxide particles having a connected structure in which porous primary particles composed of an assembly of fine crystallites are connected to each other in a bead shape. However, the Inaba NPL filed on 12/30/25, by an inventor of the present invention, suggests that the method recited in claim 12 produces a particular structure which is different from that of Tsukuda (see the Inaba NPL and the disclosure of Tsukuda). Moreover, Kakinuma has been previously applied for teaching a catalyst layer comprising a bead structure, but the structure is not made by the method recited in claim 12 and omits the fine crystallites of claim 1. Therefore, the invention of claim 12 is found to be nonobvious over the disclosures of Tsukuda and Kakinuma.
A diligent search has been performed, but has not yielded a closer prior art which can cure the deficiency of Tsukuda or Kakainuma, or which can independently teach the invention of claim 12, including all the positively recited structural limitations of base claim 1. Therefore, claim 12 is not rejected, but is objected to for being dependent on a rejected base claim 1.
Response to Arguments
Applicant’s arguments filed on 8/12/26 have been fully considered, but are not persuasive. Applicant presents the following arguments
Tsukuda fails to teach a connected structure because in the present application the term “connected structure” refers to a structure in which porous primary particles are linked via chemical bonds obtained by a particular method. Applicant relies on paragraphs [0057] to [0100] of the present application in support of the argument. In response, although claims must be read in light of the specification to determine the broadest reasonable interpretation during patent prosecution, as described in MPEP 2111, “reading a claim in light of the specification, to thereby interpret limitations explicitly recited in the claim, is a quite different thing from ‘reading limitations of the specification into a claim,’ to thereby narrow the scope of the claim by implicitly adding disclosed limitations which have no express basis in the claim.” Here, applicant’s detailed description, including but not limited to paragraphs [0057] through [0100] does not include a limiting definition of “connected structure” and certainly does not limit the definition thereof to a structure in which porous primary particles are linked via chemical bonds as argued by applicant. Thus, there is no express basis to interpret “connected structure” of claim 1 to require linking chemical bonds. MPEP 2111 mandates that claims be given their broadest reasonable interpretation by the Office during patent prosecution, with it being applicant’s prerogative to amend the claims.
Tsukuda is manufactured by a different method than that used by applicant to obtain the claimed invention. In response, the method of manufacture is not recited in claim 1; therefore, the prior art is not required to teach the same method of manufacture as applicant. Although the method of applicant’s specification may imply chemical bonding between primary particles, the claims as worded do not require this feature.
The double-patenting rejections over USP 12,304,830 have been withdrawn in view of the filing and acceptance of the Terminal Disclaimer on 7/16/26. However, art rejections for claims 1-11 remain.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1, 2, 4 and 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Tsukuda (US 2017/0279143).
Regarding claims 1-2, Tsukuda teaches a catalyst layer (paragraphs [0002, 0009]; Fig. 1 item 2; Fig. 4), comprising: an electrode catalyst (paragraph [0047]), and an ionomer (paragraph [0050]), wherein the electrode catalyst particles having a structure (connected structure) in which porous primary particles composed of an assembly of fine crystallites are connected to each other in a bead shape (see Fig. 4 which illustrates tin oxide particles comprising connected bead-like particles formed as an agglomeration of fine crystallites such that an internal porous structure is formed within the beads; the Examiner’s Modified Fig. 4 below delineates a plurality of individual beads pressed together to form the structure, each bead formed by smaller crystallites such that internal porous structure is present; see also paragraph [0046] which mentions 5-200 nm sized “primary particles” which are readable on the claimed crystallites while the larger particles [such as in Examiner’s Modified Fig. 4] are of a micron scale size; see also the description of “generally spherical” particles at paragraph [0082]) and Pt-based fine particles supported on the surface of the tin oxide-based particles (paragraph [0047]), wherein the catalyst particles art tin-oxide particles (paragraph [0045]). Tsukuda further teaches wherein the tin oxide-based particles include Sb, Nb, Ta, and/or W-doped SnO2 (paragraph [0045]).
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Tsukuda does not expressly teach that specific surface area of the tin-oxide particle support has a specific surface area of 30 m2/g or more.
However, Tsukuda does teach that it is preferred for the support to have a “high specific surface area” and gives a preferred range of 10 to 500 m2/g (paragraph [0046]).
The claimed range of 30 m2/g or more is found to be obvious because the Kakinuma range largely overlaps the claimed range, and Kakinuma further teaches that the high values are desirable.
Regarding claim 4, the cited art remains as applied to claim 1. Tsukuda further teaches wherein a conductivity of a green compact composed of the tin oxide-based particles is 1×10−3 S/cm or more (e.g. 1.31 ohm cm at Table 2 converts to 0.763 X 10-3 S/cm. The claimed range is found to be taught as 0.763 X 10-3 S/cm rounds to 1 X 10-3 S/cm with one significant digit).
Alternatively, the 1×10−3 S/cm or more range is found to be obvious over Tsukuda because Tsukuda teaches the oxide of the support should have electron conductivity, such as a volume resistivity of 1 M[Symbol font/0x57]cm or less (paragraph [0045]) suggesting an overlapping range. Absent further limitation which enables the conductivity of 1×10−3 S/cm or more, the recitation is merely aspirational as there is no upper limit on the conductivity and there is not specific claimed structure that enables achievement of the high conductivity value. Since Tsukuda teaches the same aspiration, the limitation is found to be obvious.
Regarding claim 5, the cited art remains as applied to claim 1. Tsukuda further does not expressly teach wherein an average particle diameter of the Pt-based fine particles is 5 nm or less.
However, Tsukuda does teach the particles having an average size of 1 to 10 nm (paragraph [0047]).
The claimed range is found to be obvious for overlapping the prior art range at least at 1-5 nm, which is a significant portion of the prior art range (See MPEP 2144.05 for more information on obviousness associated with overlapping ranges).
Claims 3 is/are rejected under 35 U.S.C. 103 as being unpatentable over the combination of Tsukuda (US 2017/0279143) and Watanabe (US 2012/0295184).
Regarding claim 3, the cited art remains as applied to claim 1. Tsukuda teaches that the tin-oxide based particle may be doped with Sb (see rejection of claim 2), but does not appear to teach wherein the tin oxide-based particles include Sb-doped SnO2, and a doping amount of Sb in the Sb-doped SnO2 is 2.5 at % or more and 15.0 at % or less.
In the fuel cell art, Watanabe teaches a catalyst support tin oxide, wherein the tin oxide is SnO2 is doped with four atomic percent Sb (“Sn0.96Sb0.04O2”, paragraph [0075]).
The replacement of the antimony doped tin-oxide of Tsukuda with the Sn0.96Sb0.04O2 taught by Watanabe merely requires the simple substitution of one known element for another to yield the predictable result of a functional catalyst system; therefore, a prima facie case of obviousness for substitution exists. The Watanabe Sn0.96Sb0.04O2 lies within the claimed Sb range, the claim 3 is obvious over the cited art.
Claim 6 is/are rejected under 35 U.S.C. 103 as being unpatentable over the combination of Tsukuda (US 2017/0279143) and Kitabatake (US 2023/0049734).
Regarding claim 6, Tsukuda remains as applied to claim 1. Tsukuda does not appear to teach wherein a ratio (=I/S) of a mass (I) of the ionomer to a mass (S) of the tin oxide-based particles is 0.13 or more and 0.39 or less.
In the fuel cell art, Kitabatake teaches that an electrode catalyst layer may be configured to include an ionomer for the benefit of improving performance of the catalyst layer, and that it is advantageous to adjust the amount of the ionomer and the amount of the catalyst/support composite, such that the I/M ratio is 0.07 or more and 0.25 or less, for the benefit of improving the performance of the electrode catalyst layer (paragraph [0033]).
It would have been obvious to a person having ordinary skill in the art at the time of invention to modify the catalyst layer of Tsukuda by including ionomer at an ionomer to catalyst/support ratio of is 0.07 to 0.25 for the benefit of improving the performance of the catalyst layer as taught by Kitabatake. The claimed range is found to be obvious since the presence of ionomer is suggested, with the ionomer to catalyst ratio being a result effective variable, and the prior art suggested range substantially overlaps the claimed range.
Claims 7 and 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over the combination of Tsukuda (US 2017/0279143) and Edwards (US 2007/0031322).
Regarding claim 7 and 8, the cited art remains as applied to claim 1-3. The requirement that the specific surface area is 90 m2/g or more is found to be obvious for similar reasons as the 30 m2/g or more requirement of claim 1, namely that Tsukuda teaches a substantially overlapping range.
Tsukuda further teaches that catalyst layer may comprise pores of preferably 5 to 50 nm size (paragraph [0046]), but does not expressly teach the narrowed range wherein a pore diameter of the tin oxide-based particles is 5 nm or more and 8 nm or less.
In the fuel cell art, Edwards teaches that catalyst materials with a substantial number of small pores, such as less than 7 nm, tend to exhibit high surface area, which is useful in catalyst applications as the catalyst uses the surface area (paragraph [0019]).
It would have been obvious to a person having ordinary skill in the art at the time of invention to configure the primary particles to include pores having a diameter of less than 7 nm for the benefit of increasing the surface area for catalysis as taught by Edwards. The claimed range of 5 nm to 8 nm is found to be obvious over the cited art because the less than 7 nm range overlaps the claimed range at least at 5 to 7 nm, and differences in scale do not provide patentability absent a showing of functional criticality associated with the difference (MPEP 2144.04 IVA).
Claims 9 and 10 is/are rejected under 35 U.S.C. 103 as being unpatentable over the combination of Tsukuda (US 2017/0279143) and Steinback (US 2022/0059849).
Regarding claims 9 and 10, the cited art remains as applied to claim 1. Tsukuda further teaches that the catalysts of the invention provide “improved power output and small humidity dependence of power output” (paragraph [0008]), implying favorable behavior under both low and high humidity conditions, but is silent as to the mass activity under the conditions described in claims 9 and 10.
Additionally, in the fuel cell art, Steinback teaches: “PEMFC electrocatalysts often comprise platinum, a relatively expensive precious metal. It is typically desirable to minimize the platinum content in PEMFC devices to minimize cost. Sufficient platinum content, however, is needed to provide sufficient catalytic activity and PEMFC device performance. As such, there is a desire to increase the catalyst activity per unit catalyst mass (mass activity). There are two general approaches to increase the mass activity, namely increasing the catalyst activity per unit catalyst surface area (specific activity) and increasing the catalyst surface area per catalyst mass (specific surface area or specific area). The HOR and ORR occur on the catalyst surface, so increasing the specific surface area and/or the specific activity can reduce the amount of catalyst needed to achieve a desired absolute performance, reducing cost” at paragraph [0002].
The claimed invention is found to be unpatentable over the cited art because either i) the catalyst layer of tsukuda (in view of the secondary references applied in the rejection of claim 1 would possess the claimed mass activity if measured under the same conditions due to the structural similarity previously set forth and the disclosure of output independence on humidity, or ii) it would have been obvious to increase the mass activity in order to minimize the amount of platinum required in the catalyst layer, with Steinback expressly teaching it desirable to reduce platinum content and suggesting techniques for increasing mass activity. It is noted that claims 9 and 10 merely set forth ranges expressing high mass activity without adding additional structure beyond that recited in claim 1 which facilitates achievement of the high mass activity which is claimed.
Claims 11 is/are rejected under 35 U.S.C. 103 as being unpatentable over the combination of Tsukuda (US 2017/0279143) and Easton (US 2021/0351415).
Regarding claims 11, the cited art remains as applied to claim 1. Tsukuda is silent as to the ECSA reduction ratio measured under the conditions described in claim 11.
However, in the fuel cell art, Easton teaches that a known problem in PEM fuel cells is lack of durability due to decrease in surface area (ECSA) of supported catalysts, particularly when the support is a carbon material, and the use of metal oxide is adopted in order to mitigate this deterioration (paragraph [0003]), indicating that enhanced durability of ECSA is associated with the selection of a particular catalyst support material. Easton further teaches inventive embodiments wherein the electrocatalyst exhibits only slight decay over thousands of cycles, significantly outperforming carbon supported catalysts (paragraphs [0107-0114]).
The claimed invention is found to be unpatentable over the cited art because either i) the catalyst layer of Tsukuda (in view of the secondary references applied in the rejection of claim 1 would possess the claimed ECSA reduction ratio if measured under the same conditions due to the structural similarity previously set forth, or ii) it would have been obvious to decrease the ECSA reduction ratio to the claimed amount through routine experimentation designed to achieve the known goal of minimizing the surface area loss as taught by Easton. It is noted that claim 11 merely set forth an achievement in terms of ECSA reduction without adding additional structure, elements, or features beyond that recited in claim 1 which facilitates achievement of the claimed property.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JEREMIAH R SMITH whose telephone number is (571)270-7005. The examiner can normally be reached Mon-Fri: 9 AM-5 PM (EST).
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/JEREMIAH R SMITH/Primary Examiner, Art Unit 1723
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