Cathode catalyst patents

Recently, rhodium and ruthenium-based carbon-supported sulfide electrocatalysts were synthesized by different established methods and evaluated as ODP cathodic catalysts in a chlorine-saturated hydrochloric acid environment with respect to both economic and industrial considerations [46]. In particular, patented E-TEK methods as well as a non-aqueous method were used to produce binary RhjcSy and Ru Sy in addition, some of the more popular Mo, Co, Rh, and Redoped RuxSy catalysts for acid electrolyte fuel cell ORR applications were also prepared. The roles of both crystallinity and morphology of the electrocatalysts were investigated. Their activity for ORR was compared to state-of-the-art Pt/C and Rh/C systems. The Rh Sy/C, CojcRuyS /C, and Ru Sy/C materials synthesized by the E-TEK methods exhibited appreciable stability and activity for ORR under these conditions. The Ru-based materials showed good depolarizing behavior. Considering that ruthenium is about seven times less expensive than rhodium, these Ru-based electrocatalysts may prove to be a viable low-cost alternative to Rh Sy systems for the ODC HCl electrolysis industry. 

Cathode Catalyst Performances For Those U.S. Patents Referenced... 

Table 4 records the US patents that have been issued on various PAFC cathode-catalyst ordered alloys. 

Identified an alternative binary platinum- patent pending/Carbon (Pt-X/C) cathode catalyst allowing DMFC operation at a voltage 60-80 millivolts (mV) higher than state-of-the-art platinum/carbon (Pt/ C) catalysts. 

In our FY 2002 research, we have focused on the performance of carbon-supported cathode catalysts, especially at low Pt loading. A major achievement has been the introduction of a new binary catalyst, Pt-X (patent application pending). In addition to showing higher activity towards oxygen (concluded... 

Bett JAS, Breault RD, Cipollini N et al (2004) Fuel cell having a corrosion resistant and protected cathode catalyst layer. US Patent 2004/0126644 Al... 

Lead dichloride occurs in nature as the mineral cotunnite. The compound is used in making many basic chlorides, such as Pattison s lead white. Turner s Patent Yellow, and Verona Yellow, used as pigments. Also, it is used as a flux for galvanizing steel as a flame retardant in nylon wire coatings as a cathode for seawater batteries to remove H2S and ozone from effluent gases as a sterilization indicator as a polymerization catalyst for alpha-olefins and as a co-catalyst in manufacturing acrylonitrile. 

The next advance in development of PAFC binary-alloy cathode electrocatalysts was the use of Pt-Cr alloys.27 In this patent, it was disclosed that with the platinum-vanadium alloy in 99 % phosphoric acid at 194 °C and at an electrode potential 0.9 volts, over 67 % by weight of the vanadium had dissolved in the first 36 hours. In the case of Pt-Cr, only 37 % had dissolved under the same conditions. It is not clear from the descriptions in these patents whether or not there is any unreacted vanadium or chromium present in the catalyst because it is not identified that all of the vanadium or all of the chromium was initially alloyed with the platinum. It is conceivable that significant amounts of the non-noble metal components are not fully reacted. 

The oligomerizations of dienes catalyzed by nickel18 and cobalt19 complexes formed by electrochemical syntheses have already been described. Furthermore, it is worth mentioning here the electrosynthesis, patented by Lehmkuhl20,21, metal chelates of which have been proposed as catalysts for some polymerization reactions. The reaction is a good example of paired electrochemical syntheses, in which both the anodic and cathodic processes contribute to the overall reaction ... 

There are a lot of articles and patents that describe the preparation of several types of GDEs. These electrodes can be used as anodes or cathodes, depending on the electrocatalyst present in them. We will report below general procedmes for their preparation, mainly focused to the manufacture of hydrogen diffusion electrodes [5]. The main steps in the fabrication of GDEs are the preparation of the gas diffusion medium and the preparation and apphcation of the catalyst layer. 

Jaouen patented a novel cathode structure for a solid polymer fuel cell [96] that cathode structure consisted of a solid polymer anion-exchange membrane surrounding the catalysts particles (entirely within the cathode structure), which was in contact (surrounded) with a cation-conducting polymer membrane. 

Alcohol oxidation from Pt is one of the most studied in PCs because it is the basis of the anode reaction in direct methanol PCs. Methanol is oxidized in a six-electron reaction to COj, H and HjO on nanoscale Pt at around 0.4 V to 0.5 vs RHE. Methanol is oxidized more efficiently at lower potentials on PtRu alloys and related materials. The mechanism of the oxidation process on alloy catalysts and the form of the catalysts has been the subject of hundreds of papers and is beyond the scope of this paper. When alcohol is present on a catalyst in low concentrations as an impurity, it can be oxidized by exposing the PC to open-circuit conditions, or implementing various air starvation and transient operation methods discussed in the patent literature cited above. Methanol oxidation to COj and H completes its removal from the catalyst surface. Methanol poisoning at the cathode can also be a problem at DMFC cathodes, as methanol can easily cross over the Nafion. If the PC becomes severely contaminated, even open-circuit potentials might be too low to fully oxidize the methanol, requiring aggressive procedures to oxidize the methanol from the catalysts. 

A peculiar type of electropolymerization in atu has been patented by Sobie and Zemer These authors found that aqueous srdutions of acrylamide (the main monomer), Ayv -methylene- or A/, A -ethylenebisacrylamide (the crosslinking agent), and ZnCl2 (fh catalyst) when electrolyzed in an undivided cell by a constant potential difference, in a few seconds yield a pcdyacrylamide film coating on the cathode surface, the bulk of the system being unaffected by the polymerizatirm. 

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