DETAILED ACTION
Notice of Pre-AIA or AIA Status
1. The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Amendments
2. The applicant’s response dated 20 March 2026 has been entered into the record. The examiner acknowledges the claim amendments made did not add any new matter and the reply is considered fully responsive. Claim 27 is new. Claims 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, and 27 are pending an under examination.
3. The examiner accepts the applicant’s explanation pertaining to the citation in the specification for the wording “gastight” that was previously added to Claim 14 and Claim 19 in their response dated 20 March 2026.
Claim Rejections - 35 USC § 102
4. The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
5. Claim 27 is rejected under 35 U.S.C. 102(a)(1) as being anticipated by Schmid'627.
Schmid'627 (US Pub. No. 2021/0040627A1 - previously presented) is directed toward a separatorless GDE cell for electrochemical reactions (Title).
Regarding Claim 27, Schmid’627 discloses an electrolyzer for carbon dioxide reduction (¶47-8 discusses cathode catalysts/materials), comprising: an electrolytic cell (abstract, ¶16-7), having a cathode gas diffusion electrode (GDE-K in FIG. 5), and an anode gas diffusion electrode (GDE-A in FIG. 5). Schmid’627 further discloses the cathode gas diffusion electrode (GDE-K in FIG. 5) at a first side areally adjoins a cathode gas space (cathode space I in FIG. 5) and the anode gas diffusion electrode (GDE-A in FIG. 5) likewise with a first side adjoining an anode gas space (anode space III in FIG. 5). The cathode space I and anode space III in Schmid’627 are designed to either hold gaseous or liquid material according to ¶103, but would be gas spaces in the case of CO2 reduction to CO in which O2 forms at the anode (¶103). Schmid’627 also discusses an electrolyte space (analogous to the salt bridge space II) common to both gas diffusion electrodes as depicted in FIG. 5 and discussed in ¶15 and ¶30. The salt bridge space II (i.e.: the electrolyte space of the present invention) according to Schmid’627 in ¶15 and ¶30 reaches from the cathode gas diffusion electrode (GDE-K) to the anode gas diffusion electrode (GDE-A) and is bounded at least in sections by two gas diffusion electrodes (GDE-K and GDE-A) with their second sides facing away from the respectively assigned gas spaces (cathode space I and anode space III) as depicted in FIG. 5. Additionally, Schmid’627 discloses in ¶54 that the anode gas diffusion electrode (GDE-A) has a cation-selective coating as described in ¶78 where cation-exchangers are found in the pores of the porous layer or the pores of the active layer. Schmid’627 also indicates that the anode gas diffusion electrode is coated with an ion-conducting polymer (¶57). FIG. 5 in Schmid’627 depicts a path to feed a reactant gas supply (CO2 in ¶91) and a product gas (P-K, such as CO in ¶91) outlet apparatus as described in further detail in ¶15, and ¶42-3. Schmid’627 indicates that the structure of the electrode renders it gas tight, thus the need for extra separators or membranes is superfluous (¶14). Moreover in ¶134, Schmid’627 indicates that the operation of the cell is such that appropriate separation of the product gases can nevertheless be assured (i.e.: CO2 bubbles do not enter the anode space).
Claim Rejections - 35 USC § 103
6. 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, 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.
7. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
8. Claims 14, 15, 18, 19, and 26 are rejected under 35 U.S.C. 103 as being obvious over Schmid'627.
Schmid'627 (US Pub. No. 2021/0040627A1 - previously presented) is directed toward a separatorless GDE cell for electrochemical reactions (Title).
Regarding Claim 14, Schmid’627 discloses an electrolyzer for carbon dioxide reduction (¶47-8 discusses cathode catalysts/materials), comprising: an electrolytic cell (abstract, ¶16-7), having a cathode gas diffusion electrode (GDE-K in FIG. 5), and an anode gas diffusion electrode (GDE-A in FIG. 5). Schmid’627 further discloses the cathode gas diffusion electrode (GDE-K in FIG. 5) at a first side areally adjoins a cathode gas space (cathode space I in FIG. 5) and the anode gas diffusion electrode (GDE-A in FIG. 5) likewise with a first side adjoining an anode gas space (anode space III in FIG. 5). The cathode space I and anode space III in Schmid’627 are designed to either hold gaseous or liquid material according to ¶103, but would be gas spaces in the case of CO2 reduction to CO in which O2 forms at the anode (¶103). Schmid’627 also discusses an electrolyte space (analogous to the salt bridge space II) common to both gas diffusion electrodes as depicted in FIG. 5 and discussed in ¶15 and ¶30. The salt bridge space II (i.e.: the electrolyte space of the present invention) according to Schmid’627 in ¶15 and ¶30 reaches from the cathode gas diffusion electrode (GDE-K) to the anode gas diffusion electrode (GDE-A) and is bounded at least in sections by two gas diffusion electrodes (GDE-K and GDE-A) with their second sides facing away from the respectively assigned gas spaces (cathode space I and anode space III) as depicted in FIG. 5. Additionally, Schmid’627 discloses in ¶54 that the anode gas diffusion electrode (GDE-A) has a cation-selective coating as described in ¶78 where cation-exchangers are found in the pores of the porous layer or the pores of the active layer. Schmid’627 also indicates that the anode gas diffusion electrode is coated with an ion-conducting polymer (¶57). FIG. 5 in Schmid’627 depicts a path to feed a reactant gas supply (CO2 in ¶91) and a product gas (P-K, such as CO in ¶91) outlet apparatus as described in further detail in ¶15, and ¶42-3. Schmid’627 indicates that the structure of the electrode renders it gas tight, thus the need for extra separators or membranes is superfluous (¶14). Moreover in ¶134, Schmid’627 indicates that the operation of the cell is such that appropriate separation of the product gases can nevertheless be assured (i.e.: CO2 bubbles do not enter the anode space).
The applicant has amended Claim 14 to include that during operation, a portion of a reactant gas supplied to the cathode gas space is taken up by electrolyte in the electrolyte space, which is clearly taught by Schmid’627 since the anode and cathode share a common space, so the CO2 will have to enter the electrolyte space and be taken up by (i.e.: dissolved into) the electrolyte. Amended Claim 14 further clarifies the definition of gas tight mean the prevention at least 95% of the portion of the reactant gas in the electrolyte space from entering the anode gas space; however, Schmid’627 does not explicitly state this percentage. This value can be derived from the experimental data in Schmid’627 and the following explanation.
In ¶130, Schmid’627 indicates that the volume of gas flowed through the cathode varied from 60 mL/min to 180 mL/min depending on the current density. Schmid’627 indicates in ¶139 that the electrochemical cells were run for 15 or 60 minute time interval. When comparing the times and flow rates, the volume of gas that was passed through the cathode gas chamber ranged from 900 mL to 10,900 mL (as calculated from the product of flow rate and time). Schmid’627 indicated in ¶149 that analysis of the anodic product gas resulted in the about 200 ppm of CO and H2 being detected (as opposed to O2 which is the expected anodic product). Formation of reduction product from CO2 in the anodic gas product stream indicates crossover of CO2 into the anode gas space. Given the very low level of CO detected in the anodic product stream and assuming that the total anodic gas volume is comparable to the CO2 reactant gas flow, the incursion of CO2 into the anode space is exceptionally small. As a percentage, 200 ppm is significantly less than the claim limitation of greater than 95% as per Claim 14. Therefore, Schmid’627 meets the limitations of amended Claim 14.
Regarding Claim 15, Schmid’627 discloses the electrolyzer as claimed in Claim 14, wherein the electrolyte space is provided with an electrolyte feedline and an electrolyte drain line, which together with a pumping apparatus form an electrolyte circuit as depicted in FIG. 5 and further discussed in ¶93.
Regarding Claim 18, Schmid’627 discloses the electrolyzer as claimed in Claim 14, wherein an oxygen exhaust apparatus is provided at the anode space as depicted in FIG. 5 as the P-A and further described in ¶103 where an anode gaseous product, i.e. O2, can be removed from the anode space III.
Regarding Claim 19, Schmid’627 discloses the method operating an electrolyzer (abstract), comprising: introducing a CO2-containing reactant gas into the cathode gas space I as depicted in FIG. 5 and described in ¶103. The CO2 is then at least partially reduced to CO (i.e.: P-K in FIG. 5) at the cathode diffusion electrode (GDE-K) as described in ¶103. FIG. 5 of Schmid’627 shows that the GDE-K abuts the cathode gas space I with a first side and abuts an electrolyte space (i.e.: salt bridge space II) with the second side. ¶144 of Schmid’627 indicates that the electrolyte is saturated with carbon dioxide (i.e.: dissolve CO2 into the electrolyte). During the reduction of CO2 at the cathode, ¶103-4 of Schmid’627 indicates that molecular oxygen (i.e.: P-A in FIG. 5) is released at the anode gas diffusion electrode surface and diffuses through the anode gas diffusion electrode (¶29-30 describes the movement of formed gases from the liquid electrolyte through the porous layer and out the anode space). Schmid’627 further discloses that the cathode gas diffusion electrode and the anode gas diffusion electrode, each with a second side, adjoin the common electrolyte space (salt bridge space II) as shown in FIG. 5. ¶100 in Schmid’627 describes the removal of gases such as CO2 and O2 from the electrolyte in the salt bridge space to facilitate liquid electrolyte recycling. Additionally, Schmid’627 discloses in ¶54 that the anode gas diffusion electrode (GDE-A) has a cation-selective coating as described in ¶78 where cation-exchangers are found in the pores of the porous layer or the pores of the active layer. Schmid’627 finally indicates that the anode gas diffusion electrode is coated with an ion-conducting polymer (¶57). Schmid’627 indicates that the structure of the electrode renders it gas tight, thus the need for extra separators or membranes is superfluous (¶14). Moreover in ¶134, Schmid’627 indicates that the operation of the cell is such that appropriate separation of the product gases can nevertheless be assured (i.e.: significant CO2 bubbles do not enter the anode space).
In the operation, a portion of a reactant gas supplied to the cathode gas space is taken up by electrolyte in the electrolyte space, which is clearly taught by Schmid’627 since the anode and cathode share a common space, so the CO2 will have to enter the electrolyte space and be taken up by (i.e.: dissolved into) the electrolyte. Amended Claim 19 further clarifies the definition of gas tight mean the prevention at least 95% of the portion of the reactant gas in the electrolyte space from entering the anode gas space; however, Schmid’627 does not explicitly state this percentage. This value can be derived from the experimental data in Schmid’627 and the following explanation.
In ¶130, Schmid’627 indicates that the volume of gas flowed through the cathode varied from 60 mL/min to 180 mL/min depending on the current density. Schmid’627 indicates in ¶139 that the electrochemical cells were run for 15 or 60 minute time interval. When comparing the times and flow rates, the volume of gas that was passed through the cathode gas chamber ranged from 900 mL to 10,900 mL (as calculated from the product of flow rate and time). Schmid’627 indicated in ¶149 that analysis of the anodic product gas resulted in the about 200 ppm of CO and H2 being detected (as opposed to O2 which is the expected anodic product). Formation of reduction product from CO2 in the anodic gas product stream indicates crossover of CO2 into the anode gas space. Given the very low level of CO detected in the anodic product stream and assuming that the total anodic gas volume is comparable to the CO2 reactant gas flow, the incursion of CO2 into the anode space is exceptionally small. As a percentage, 200 ppm is significantly less than the claim limitation of greater than 95% as per Claim 19. Therefore, Schmid’627 meets the limitations of amended Claim 19.
Regarding Claim 26, Schmid’627 discloses the electrolyzer in Claim 14, wherein the cation-selective coating is coated on the second side of the anode diffusion electrode discloses in ¶78 where cation-exchangers are found in the pores of the porous layer or the pores of the active layer. By their very nature, gas diffusion electrodes are required to be porous since materials (liquid and gases) moves through said materials, which typically include: base materials like titanium mesh, titanium fibers, nickel foam, nickel mesh, carbon felts, carbon cloth, and the like. Since gas diffusion electrodes and the base materials are porous, application process of a cation-selective coating is capable of having the cation-selective species penetrate into the pores and provide said cation-selective species within the pores. This means that the cation-selective material is found throughout the entire anode gas diffusion electrode including extending to the second side of the anode as required by Claim 26.
9. Claims 16, 17, and 23 are rejected under 35 U.S.C. 103 as being unpatentable over Schmid’627 as applied to Claim 15 (for 16 and 17) and Claim 19 (for 23) above, and further in view of Baldauf’222.
Schmid'627 (US Pub. No. 2021/0040627A1 - previously presented) is directed toward a separatorless GDE cell for electrochemical reactions (Title). Baldauf’222 (US Pub. No. 2019/0078222 A1 – previously presented) is directed toward the electrochemical utilization of carbon dioxide (title).
Regarding Claim 16, Schmid’627 discloses the electrolyzer as claimed in Claim 15 and discloses general details about handling gases that form in the salt bridge space (¶83-85, ¶93-94, ¶99-100, and ¶103). However, Schmid’627 does not explicitly disclose a CO-2 deposition apparatus in the electrolyte circuit.
Baldauf’222 teaches methods for the electrochemical utilization of carbon dioxide where part of the material is reduced and the unreacted CO2 is separated (¶22). The FIGURE in Baldauf’222 depicts feeding CO2 into the cathode subspace 8 via various pathways (¶7-19 and ¶43-48). The combination of regeneration vessel 10 and gas scrubbing apparatus 32 are analogous to the CO2 deposition unit of the Claim 16 of the present invention. The following discussion details how CO2 is added and removed from the electrolyte (EL) or catholyte (K1) as per Baldauf’222. Cathode subspace 8 is fed CO2 from conduit 11 which feeds conduit 16 which originates from regeneration vessel 10 (FIGURE). The FIGURE in Baldauf’222 further shows that CO2 can be directly fed into the electrolyte (EL) forming catholyte (K1) which is fed into cathode sub space 7 via conduit 12. K1, which has dissolved CO2, is pumped (via element 30) into cathode subspace 7 for reaction at cathode 6 to form reduction products (FIGURE). After K1 passes through cathode subspace 7 (analogous to electrolyte space of the present application), the material transported via conduit 14 is treated in gas scrubbing apparatus 32 (FIGURE). In gas scrubbing apparatus 32, unreacted CO2 from the catholyte (K1) and the cathode gas stream (fed via conduit 15) are combined (FIGURE). The (non-product) material in the gas scrubbing unit 32 is sent back to the regeneration vessel 10 which initiates the shuttling CO2 cycle described above again (FIGURE). As per ¶27 of Baldauf’222, guiding the catholyte (electrolyte) and the product gas to be cleaned separately into scrubber (32), allows a single thermodynamic equilibrium to form (in the gas scrubbing apparatus), thereby improving the quality of the separation and lowering energy usage. Prior to the effective filing date of the claims invention, it would be obvious for one of ordinary skill in the art to modify the simple electrolyzer of Schmid’627 with the CO2 deposition apparatus (combination of regeneration vessel 10 and gas scrubbing apparatus 32) disclosed in Baldauf’222 with the reasonable expectations of efficiently reducing CO2 with a more favorable economic and energy profile (Baldauf’222 in ¶28).
Regarding Claim 17, Schmid’627 in view of Baldauf’222 discloses the electrolyzer as per Claims 14 and 16 above, wherein there is a connecting line from the CO2 deposition apparatus to the reactant gas supply apparatus as depicted in the FIGURE from Baldauf’222. Specifically, gas scrubbing unit 32 feeds CO2 via conduit 18 to the regeneration vessel 10 which feeds CO2 via conduit 16 to the reactant gas entering cathode subspace 8 by way of conduit 11 (FIGURE in Baldauf’222).
Regarding Claim 23, Schmid’627 discloses the method as claimed in Claim 19. Schmid’627 discloses general details about handling gases that form in the salt bridge space (¶83-85, ¶93-94, ¶99-100, and ¶103). However, Schmid’627 does not explicitly disclose a method wherein the CO-2 discharged from the electrolyte is supplied to the CO2-containing reactant gas.
Baldauf’222 teaches methods for the electrochemical utilization of carbon dioxide where part of the material is reduced and the unreacted CO2 is separated (¶22). The FIGURE in Baldauf’222 depicts feeding the CO2-containing reactive gas into the cathode subspace 8 via various pathways (¶7-19 and ¶43-48). Pertaining to Claim 23 of the present application, the material (K1 containing CO2 gas) transported via conduit 14 is treated in gas scrubbing apparatus 32 (FIGURE in Baldauf’222). According to the FIGURE of Baldauf’222, gas scrubbing unit 32 feeds CO2 via conduit 18 to the regeneration vessel 10 which feeds CO2 via conduit 16 to the reactant gas entering cathode subspace 8 by way of conduit 11 (FIGURE in Baldauf’222). As per ¶27 of Baldauf’222, guiding the catholyte (electrolyte) and the product gas to be cleaned separately into scrubber (32), allows a single thermodynamic equilibrium to form (in the gas scrubbing apparatus), thereby improving the quality of the separation and lowering energy usage. Before the effective filing date of the claimed invention, it would be obvious for one of ordinary skill in the art to modify the method of operating the simple electrolyzer of Schmid’627 with a way to recycle the discharged CO2 from the electrolyte back into the reactant gas stream as taught by Baldauf’222 with the reasonable expectations of efficiently reducing CO2 with a more favorable economic and energy profile (Baldauf’222 in ¶28).
10. Claims 20 and 21 are rejected under 35 U.S.C. 103 as being unpatentable over Schmid'627 as applied to Claim 19 above, and further in view of Rudnev-2017.
Schmid'627 (US Pub. No. 2021/0040627A1 - previously presented) is directed toward a separatorless GDE cell for electrochemical reactions (Title). Rudnev-2017 (“Transport Matters: Boosting CO2 Electroreduction in Mixtures of [BMIm][BF4]/Water by Enhanced Diffusion,” ChemPhysChem 2017, 18, 3153-3162 – previously presented) is directed toward understanding the effect of electrolyte composition (water to ionic liquid ratio) on CO2 electroreduction (pg. 3153: title and abstract).
Regarding Claim 20, Schmid’627 discloses the method as claimed in Claim 19 wherein the electrolyte comprises an aqueous solution of initially 1 M K2CO3 and then 2 M KHCO3 to neutralize the pH shift toward neutral during cell operation as noted in ¶138. Schmid’627 discloses other electrolytes can be used by, but does not offer specific examples in ¶107. Therefore, Schmid’627 does not explicitly teach an electrolyte not based on a salt of carbonic acid.
Rudnev-2017 discloses that room temperature ionic liquids (RTIL) have been used as a medium for CO2 electroreduction (pg. 3154-5: section 1. Introduction), but these materials have high viscosity which lowers CO2 transport and reduces reaction rate. Rudnev-2017 conducted a series of experiments in which water was added to 1-butyl-3-imidazolium tetrafluoroborate, [BMim][BF4], at specific ratios and the impact on viscosity (pg. 3156: Fig. 3c), electrolyte pH (pg. 3156: Fig. 3d), CO2 reduction (pg. 3160: Fig. 7), CO2 diffusion rate (pg. 3156: Fig. 3a) among other properties were evaluated using Ag as the cathode catalyst (pg. 3154: introduction section). Since Claim 20 of the present application has the limitation of an aqueous salt solution, the 70 mol% water+30 mol% [BMim][BF4] in Rudnev-2017 meets said limitation. Rudnev-2017 found that a 30 mol % [BMim][BF4] in water (under saturated CO2 conditions) results in a pH of ~5 (pg. 3156: Fig. 3d), >95% faradaic efficiency (pg. 3160: ), and >90% reduction product of CO (over H2). It would be obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the electrolyte in the method of operating an electrolyzer of Schmid’627 by using 30 mol% RTIL in water as taught by Rudnev-2017 with the reasonable expectation of reducing CO2 to CO with improved efficiency as described in the conclusion section of Rudnev-2017 on pg. 3160.
Regarding Claim 21, Schmid’627 discloses the method as claimed in Claim 19 wherein the electrolyte comprises an aqueous solution of initially 1 M K2CO3 and then 2 M KHCO3 to neutralize the pH shift toward neutral during cell operation as noted in ¶138 and has a pH value ~8 as depicted in FIG. 8 and listed in ¶144 in Schmid’627. Therefore, Schmid’627 does not discuss the effects of an acidic (to neutral) pH on the electroreduction of carbon dioxide.
Rudnev-2017 discloses that room temperature ionic liquids (RTIL) have been used as a medium for CO2 electroreduction (pg. 3154-5: section 1. Introduction), but these materials have high viscosity which lowers CO2 transport and reduces reaction rate. Rudnev-2017 conducted a series of experiments in which water was added to 1-butyl-3-imidazolium tetrafluoroborate, [BMim][BF4], at specific ratios and the impact on viscosity (pg. 3156: Fig. 3c), electrolyte pH (pg. 3156: Fig. 3d), CO2 reduction (pg. 3160: Fig. 7), CO2 diffusion rate (pg. 3156: Fig. 3a) among other properties were evaluated using Ag as the cathode catalyst (pg. 3154: introduction section). Specifically, Rudnev-2017 indicates electrolyte mixtures of water and [BMim][BF4] saturated with CO2 ranged from ~4 to 6.5 according to Fig. 3d on pg. 3156. It has been held that a prima facie case of obviousness exists when the range disclosed in the prior art overlaps with the claimed range (i.e.: pH <7). See MPEP 2144.05(I).
Rudnev-2017 concluded that inclusion of water into a RTIL electrolyte increased efficiency for two main reasons: water acts as a proton source for the electroreduction process reducing the applied cathodic potentials at a given current and water decreased the viscosity of the RTIL thereby enhancing the diffusion of the reacting species as per the conclusion section on pg. 3160. It would be obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the electrolyte in the method of operating an electrolyzer as taught by Schmid’627 by using 30 mol% RTIL in water as taught by Rudnev-2017 with the reasonable expectation of reducing CO2 to CO with improved efficiency (Rudnev-2017 on pg. 3160: Section 3. Conclusion).
11. Claim 22 is rejected under 35 U.S.C. 103 as being unpatentable over Schmid'627 as applied to Claim 19 above, and further in view of Gao-2015.
Schmid'627 (US Pub. No. 2021/0040627A1 - previously presented) is directed toward a separatorless GDE cell for electrochemical reactions (Title). Gao-2015 (“pH effect on electrocatalytic reduction of CO2 over Pd and Pt nanoparticle,” Electrochem. Comm. 2015, 55, 1-5) is directed toward the effect of pH on CO2 reduction over H2 formation (pg. 1: abstract and introduction).
Regarding Claim 22, Schmid’627 discloses the method as claimed in Claim 19 wherein the electrolyte comprises an aqueous solution of initially 1 M K2CO3 and then 2 M KHCO3 to neutralize the pH shift toward neutral during cell operation as noted in ¶138 and has a pH value ~8 as depicted in FIG. 8 and listed in ¶144 in Schmid’627. Therefore, Schmid’627 does not discuss the effects of an acidic (to neutral) pH on the electroreduction of carbon dioxide.
Gao et al. is directed toward understanding the reduction of CO2 at low pH values where adsorbed hydrogen participates in the electrocatalytic reduction of CO2 and competitive hydrogen evolution reaction simultaneously (pg. 1: abstract). Gao et al. used Pt and Pd nanoparticles as CO2 reduction catalysts (pg. 1: abstract). In the experimental section, Gao-2015 explains that electrocatalytic reduction of CO2 was conducted in CO2-saturated electrolyte solutions with different compositions to obtain a series of pH values (pH 4.2, pH 2.7, pH 2.2; pH 2.0, pH 1.8, and pH 1.5 using mixtures of potassium sulfate and sulfuric acid. The same reduction conditions were also conducted under an Ar atmosphere to understand how effective HER reduction was using the electrolytes above and the different catalyst nanoparticles. It was found that CO2 reduction was effectively conducted at pH 2.2 to pH 4.0 with higher levels of HER reduction at pH values less than 2 (Fig. 2a on pg. 3 and Fig. 3a on pg. 4). Therefore, Gao-2015 indicates in the conclusion section on pg. 4 that reduction over Pd NPs, Faradaic efficiency for CO production at −1.19 V (vs. RHE) increased with increasing pH and the current density for CO production over Pd NPs at −1.19 V (vs. RHE) reaches maximum at pH of 2.2. The work of Gao-2015 demonstrated that tuning the hydrogen binding energy by adjusting pH value of the electrolyte could be an effective way to facilitate CO2 reduction over Pd NPs.
It would be obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the electrolyte and the catalyst in the method of operating an electrolyzer of Schmid’627 by the electrolytes H2SO4/K2SO4 and Pd nanoparticle catalysts as taught by Gao-2105 with using 30 mol% RTIL in water as taught by Rudnev-2017 with the reasonable expectation of controlling pH value of the electrolyte and the catalyst (i.e.: Pd NP) as a means to facilitate the electrochemically efficient reduction of CO2.
It has been held that a prima facie case of obviousness exists when the range disclosed in the prior art overlaps with the claimed range (i.e. pH less than 4). See MPEP 2144.05(I).
11. Claims 24 and 25 are rejected under 35 U.S.C. 103 as being unpatentable over Schmid’627 as applied to Claim 19, and further in view of Yang-2017.
Schmid'627 (US Pub. No. 2021/0040627A1 - previously presented) is directed toward a separatorless GDE cell for electrochemical reactions (Title). Yang-2017 (“Electrochemical conversion of CO2 to formic acid utilizing Sustainion membranes,” J. CO₂ Utilization 2017, 20, 208-221 – previously presented) discloses the use of cation exchange membranes in an electrochemical CO2 cell (pg. 208: title).
Regarding Claim 24, Schmid’627 discloses the method as claimed in Claim 19. Schmid’627 varied the flow rate of CO2 to the GDE-K and current densities (¶130) to completely convert all CO2 to CO at the cathode (¶135) with GC analysis of the resultant products leaving the anode and the cathode gas spaces. Schmid’627 found a ratio of ~2:1 CO2:O2 (FIG. 7) for gaseous products leaving the anode space. That specific composition indicates that CO32-, the primary byproduct of CO2 reduction to CO at the cathode, was electrochemically destroyed at the anode to from CO2 which then diffused into the anode space (¶142-3). Schmid’627 indicates that the release of CO2 at the anode could be prevented or at least reduced by the introduction of specific transport layers into the GDE-A (¶144). However, Schmid’627 does not teach a ratio of CO2 volume flow at the cathode gas diffusion electrode to CO2 volume flow at the anode gas diffusion electrode of greater than 5 as per Claim 24.
Yang-2017 discloses the use of cation exchange membranes in an electrochemical CO2 cell in which carbon dioxide is converted to formic acid/formate (pg. 208. Yang-2017). Yang-2017 indicates that bicarbonate and formate anions can both be oxidized to CO2 at the anode according to equations (8) and (9) on pg. 211 (Section 2.6. Cation ion exchange membrane selection). On pg. 212, Yang-2017 indicates that the cation ion selective membrane must have the ability to block or limit the transport of formate ions (and by analogy bicarbonate ions). Yang-2017 further indicates that formate oxidized to CO2 at the anode can be detected in the anode product gas stream (pg. 214: Section 3.4. Formate ion transport into anode compartment). Yang-2017 initially used the thinner Nafion 212 material to allow the application of a lower cell voltage during the reduction process (pg. 214: Section 3.4. Formate ion transport into anode compartment). However, Yang-2017 found that the thicker Nafion 324 membrane (150 microns) when compared to thinner Nafion 212 (50.8 microns) or Nafion 115 (127 microns) had virtually no carbon dioxide in the anode product stream (0.03 CO2 to 1.0 O2) as per Table 6 (pg. 214).
It would be obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the ion transport layer described in ¶144 of Schmid’627 with a cationic ion material as disclosed in Yang-2017 with the reasonable expectation of reducing CO2 evolution at the anode from the oxidation of carbonate or bicarbonate. The lower concentration of CO2 directly results from the inability of (bi)carbonate to access the anode electrode interface since the cation ion exchange material with its negatively charged groups (e.g.: sulfonate groups in Nafion) repels the diffusion of anions as taught on pg. 211 in Yang-2017 (Section 2.6. Cation ion exchange membrane selection)
Since the combination of Schmid’627 and Yang-2017 discloses the thickness of cation exchange material impacts the ability of the anions (e.g.: bicarbonate) to diffuse to anode, modulating the thickness of the cation exchange material directly impacts the CO2 gas volume flow at the anode gas diffusion electrode. Additionally, Schmid’627 discloses modulation of the flow rate of CO2 at the cathode diffusion electrode (¶130-3). Therefore, the ratio of CO2 volume flow at the cathode gas diffusion electrode to the anode gas diffusion electrode is a results-effective variable, i.e., a variable which achieves a recognized result, and the determination of the optimum or workable ranges of said variable might be characterized as routine experimentation (See MPEP 2144.0.II.B.). Accordingly, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to have discovered the optimum or workable ranges of ratio of CO2 volume flow at the cathode gas diffusion electrode to the anode gas diffusion electrode, including values within the claimed range, through routine experimentation by modulation of the thickness of the cation exchange layer that is applied to the anode gas diffusion electrode. One of ordinary skill would target a sufficient thickness of cation ion exchange material to prevent the diffusion of carbonate to the anode interface while maintaining the application of the lowest cell voltage to still facilitate effective formation of carbon monoxide.
Regarding Claim 25, Schmid’627 in combination with Yang-2017 disclose the method as claimed in Claim 24, wherein the gas volume flow of the CO2 at the cathode gas diffusion electrode is at least 15 times as great as at the anode gas diffusion electrode. Specifically, this ratio could be easily derived by one of ordinary skill in the art through routine optimization as described above in Claim 24 by modulating the thickness of the cationic exchange material to lower the incidence of bicarbonate oxidation to CO2 at the anode while maintaining the application of the lowest cell voltage to still facilitate effective formation of carbon monoxide.
Response to Arguments
12. Applicant's arguments filed 20 March 2026 have been fully considered and are persuasive pertaining to the rejection of independent Claim 14 and Claim 19 as being anticipated by Schmid’627 but they are not persuasive. As a result, the previous rejection is withdrawn, and updated grounds for the rejection of Claim 14 and Claim 19 as a well as the subsequent dependent claims are explained in detail above.
13. Pertaining to Claim 22, the rejection has been updated to reflect the amendment which adjusted the pH of the electrolyte to less than 4.
14. Pertaining to new Claim 27 (which is identical to a previous version of Claim 14), the response to the applicant’s arguments are below. The applicant has argued that Schmid’627 does not teach the gastight nature of the cation-selective coating applied to the anode gas diffusion electrode. The examiner disagrees with this assessment as Schmid’627 indicates that the structure of the electrode renders it gastight, thus the need for extra separators or membranes is superfluous (¶14). Moreover in ¶134, Schmid’627 indicates that the operation of the cell is such that appropriate separation of the product gases can nevertheless be assured (i.e.: CO2 bubbles do not enter the anode space). Therefore, Schmid’627 meets the amended limitations of Claims 14 and 19.
Conclusion
15. Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
16. Any inquiry concerning this communication or earlier communications from the examiner should be directed to KEVIN SYLVESTER whose telephone number is (703)756-5536. The examiner can normally be reached Mon - Fri 8:15 AM to 4:30 PM EST.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, James Lin can be reached at 571-272-8902. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
17. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/KEVIN SYLVESTER/Examiner, Art Unit 1794
/CIEL P CONTRERAS/Primary Examiner, Art Unit 1794
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