Commercial Platinum Catalyst Research Articles

Electrochemical study of methanol tolerant oxygen reduction reaction PdxCoy/C-catalysts from organometallic molecular precursors

In this work, we study the mechanism and kinetics of the oxygen reduction reaction (ORR) over Pd/C, Pd2Co/C and PdCo2/C electrocatalysts synthesized by thermal reduction of organometallic precursors, such as [Pd3(μ-3-Ph-pz)6], [Et4N]2[Pd2Co(μ-4-I-3,5-Me2-pz)4Cl4], and [Et4N]2[PdCo2(μ-4-I-3,5-Me2-pz)4Cl4]. The methanol tolerance and formation of peroxide under oxygen reduction reaction conditions were determined using a rotating disk electrode (RDE) and a rotating ring disk electrode (RRDE). The Pd2Co/C catalysts prepared from [Et4N]2[PdCo2(4-I-3,5-Me2-pz)4Cl4] showed the best ORR activity and higher methanol tolerance, compared with commercial platinum catalysts. The ORR electron transfer number for Pd2Co/C was 3.7, similar to the Pd/C commercial catalysts. Compared to the commercial catalysts, Pd2Co/C and PdCo2/C showed the highest hydrogen peroxide formation (%H2O2), 16 and 24%, respectively. Electrogeneration of hydrogen peroxide has potential application in advanced oxidation processes.

A Generic Conversion Strategy: From 2D Metal Carbides (MxCy) to M‐Self‐Doped Graphene toward High‐Efficiency Energy Applications

This study first presents a subtle thermal‐chlorination strategy for a universal transformation of abundant 2D metal carbides (MxCy, e.g., Cr3C2, Mo2C, NbC, and VC) to 2D graphene and M‐self‐doped graphene (MG). The as‐obtained MG endows a transparent sheet architecture of one to four atomic layers. Simultaneously, MG with different M amounts is synthesized by tuning the chlorination parameters. Among them, the novel and representative Cr‐self‐doped graphene with optimal Cr amount (4.81 at%) demonstrates the outstanding electrochemical performance. It presents an energy density of 686 W h per kg electrode and a power density of more than 391 W per kg electrode as anode material of Li ion batteries, and four‐fold activity against the commercial iridium oxide electrode toward oxygen evolution reaction as well as a comparable oxygen reduction reaction performance to the commercial platinum catalyst. Moreover, this method is readily scalable to produce graphene and MG electrode materials on industrial levels.

Novel continuous catalytic hydrogenation process for the synthesis of diacetone-d-allose

Diacetone-d-allose is an important building block for the synthesis of pharmaceutical ingredients. The current batch production process involves a chemical oxidation and a reduction step that include hazardous reagents, produce a large amount of waste and require an extensive downstream processing. Current investigations aim to develop a catalytic reduction process of the intermediate diacetone-d-ketoglucose (DAKG) with molecular hydrogen, a green solvent, and a heterogeneous metal catalyst. Improvement of productivity and simultaneous reduction of the environmental impact shall be achieved by transforming the conventional batch procedure into a continuous process with a stationary catalyst packing.The screening studies presented in this work revealed that high reaction rates and a high selectivity (>98%) can be achieved with a commercial platinum catalyst under mild conditions in an aqueous buffer solution. Transition from batch into a continuous process was realized in several mini-scale fixed bed reactors to provide a fast screening and high mass transfer rates. A high selectivity (99%) and a conversion of 30% was achieved. The results indicate that the reactor performance was influenced by internal diffusion limitations and also by external mass transfer. To attain full conversion of DAKG, the reaction was performed in a random packed bed reactor and a selectivity of >96% was achieved.

Evaluating Electrospun Polyacrylic Acid-Nafion Composite As Stable Catalyst Support for PEM Fuel Cell Electrodes

Production of energy through renewable and sustainable processes are important goals for the future in the context of depleting fossil fuels and environmental pollution. In this regard fuel cell technology offers an attractive combination of highly efficient fuel utilization and environmentally friendly operation. For successful commercialization of low temperature proton exchange membrane (PEM) fuel cells, they should have a long life and a high performance. Recently, high performance fuel cell electrodes were obtained by electrospinning a solution containing proton conducting Nafion and commercial platinum catalyst powder along with PAA as electrospinning polymer. Electrospinning of the catalyst together with Nafion ionomer resulted in enhanced triple phase boundaries which resulted in high fuel cell performance. Moreover, it was also found that the stability of the electrodes is significantly higher than the electrodes prepared from the same catalyst by conventional methods. However, carbon corrosion still ensued. In this work, we demonstrate the stability of polyacrylic acid (PAA) - Nafion composite as a stable support due to which the Pt after the carbon corrosion does not come out of the system. On the contrary, it stays entrapped in the membrane electrode assembly giving significance performance even after the corrosion protocols/measurements. Here, we first produce Pt nanoparticles that are produced by a photochemical reaction of the precursor induced by UV light. To this, PAA and Nafion (1:2 by weight) were added and stirred overnight. The resulting solution was electrospun. (Small amount of carbon was added in some cases to get the desired conductivity) to get a Pt/PAA-Nafion catalyst as shown in transmission electron micrograph. The electrodes are first tested for electrochemical stability by potential cycling and then in the fuel cell test bench using the FCCJ recommended cell evaluation protocol. Figure 1

Characteristics of non-platinum cathode catalysts for a hydrogen–oxygen fuel cell with proton- and anion-conducting electrolytes

Cathode catalysts for a hydrogen–oxygen fuel cell (FC) with proton-conducting (acidic) and anion-conducting (alkaline) electrolytes are synthesized via the pyrolysis of nitrogen-containing iron and cobalt complexes on the surfaces of highly disperse carbon materials. The catalysts are characterized by X-ray photoelectron spectroscopy (XPS) and tested under model conditions on a thin-layer disk electrode and as a part of a membrane electrode assembly of hydrogen–oxygen FCs. The properties of the CoFe/C system formed via the pyrolysis of macroheterocyclic cobalt and iron compounds on carbon materials (XC-72 soot and multiwall nanotubes (MNTs)) are described for the first time. According to XPS data, the surface of the CoFe/C catalytic systems is enriched with carbon (95.5 at %) and contains nitrogen (2 at %), oxygen (2 at %), and metals (0.5 at %). According to the results from electrochemical measurements under model conditions, the CoFe/MNT catalytic systems approaches 60% Pt/C (HiSPEC9100) commercial platinum catalyst according to their activity in the oxygen reduction reaction in an alkaline medium (0.5 M KOH). The half-wave potentials are 0.85 and 0.88 V for CoFe/MNT and 60% Pt/C (HiSPEC9100) catalysts, respectively. The maximum specific powers of hydrogen–oxygen FCs with anion-conducting electrolytes are 210 mW/cm2 (60% Pt/C (HiSPEC9100) based cathode) and 180 mW/cm2 (CoFe/MNT based cathode). The characteristics of a membrane electrode assembly with a non-platinum cathode correspond to the best analogs described in the literature. The results of this work show the prospects for further studies on scaling this technology for the synthesis of the proposed non-platinum cathode catalysts and optimizing the architecture of the membrane electrode assembly of FCs based on them.

Properties of Cathode Non-Platinum Catalysts for Oxyhydrogen Fuel Cell with Proton- and Anion-conducting Electrolytes

Pyrolysis of nitrogen-containing complexes of iron and cobalt on the surface of disperse carbon materials was used for synthesis of cathode catalysts for oxyhydrogen fuel cells (FC) with proton-conducting (acidic) and anion-conducting (alkaline) electrolytes. The catalysts were characterized by XPS and tested using a thin-film disc electrode and in oxyhydrogen FC under model conditions. Properties of the CoFe/C system prepared by pyrolysis of macroheterocyclic compounds of iron and cobalt on carbon materials (soot HS-72 and multilayer nanotubes (CNT)) were described for the first time. From XPS data, the surface of the catalytic CoFe/C systems is rich in carbon (95,5 at.%), contains nitrogen (2 at.%), oxygen (2 at.%) and metals (0,5 at.%). The data obtained by electrochemical measurements under model conditions revealed that the catalytic systems CoFe/CNT are close to the commercial platinum catalyst 60%Pt/C (HiSPEC9100) in their activity to oxygen reduction in an alkali medium (0,5 M KOH). Half-wave potentials are 0,85 and 0,88 V for catalysts CoFe/CNT and 60%Pt/C (HiSPEC9100), respectively. The maximal specific capacity of the oxyhydrogen FC with an anion-conducting electrolyte is 210 mW/cm2 (a 60%Pt/C (HiSPEC9100) based cathode) and 180 mW/cm2 (CoFe/CNT based cathode). In its characteristics, MEA with the non-platinum cathode compete well with the best analogues described in literature. The results obtained demonstrated the necessity of the further studies on scaling-up the technology for synthesis of the developed non-platinum cathode catalysts and on optimization of the MEA FC architecture based thereon.

Study of the oxygen reduction and hydrogen oxidation reactions on RhIrRu-based catalysts

In this work, we have used a mixture of three carbonyl cluster compounds [Rh6(CO)16, Ir4(CO)12 and Ru3(CO)12] in order to obtain two new RhIrRu-based catalytic materials by pyrolysis in different atmospheres: neutral (N2) and reductive (H2). The products were structurally characterized by different analytical techniques. The results show that the hydrogen atmosphere favors the decarbonylation process of the precursors. The tri-metallic materials were also electrochemically characterized by rotating disk electrode measurements. These studies indicate that the new catalysts can perform the oxygen reduction reaction (ORR) even in the presence of methanol, and the hydrogen oxidation reaction (HOR) even in the presence of carbon monoxide. The polarization curves are similar in the absence and presence of such proton exchange membrane (PEM) fuel cell contaminants, an important advantage over commercial platinum catalysts, which are easily deactivated by small concentrations of these species. The kinetic parameters of the catalysts, such as Tafel slope (b), exchange current density (jo) and charge transfer coefficient (α), were calculated for both reactions, as well. The results show that the new materials are good potential candidates to be evaluated as both cathodes and anodes in PEM fuel cells.

Characterization of different plasma-treated cobalt oxide catalysts for oxygen reduction reaction in alkaline media

Plasma-synthesized cobalt oxide supported on carbon has been analyzed for its use for electrocatalytic oxygen reduction reaction (ORR) in alkaline anion exchange membrane fuel cells (AEMFC). This work presents the ORR activity in 0.1mol L−1 KOH and 0.1mol L−1 K2CO3 at 25°C. Cyclic voltammetry (CV) was used to determine the potentials at which the ORR occurs and to evaluate the stability of catalyst. Moreover, a rotating ring-disk electrode (RRDE) was used to investigate the activity of the catalysts and the formation of the by-product hydroperoxide anion (HO2−) as well as to identify the preferred pathway of the ORR. Calculated kinetic parameters for the ORR for the cobalt catalysts are shown in this work together with a comparison to a commercial platinum catalyst. However, the cobalt oxide produced more by-products which could lead to damage of the membrane in a fuel cell through a radical attack of the polymer backbone.

Interfacial electronic effects control the reaction selectivity of platinum catalysts.

Tuning the electronic structure of heterogeneous metal catalysts has emerged as an effective strategy to optimize their catalytic activities. By preparing ethylenediamine-coated ultrathin platinum nanowires as a model catalyst, here we demonstrate an interfacial electronic effect induced by simple organic modifications to control the selectivity of metal nanocatalysts during catalytic hydrogenation. This we apply to produce thermodynamically unfavourable but industrially important compounds, with ultrathin platinum nanowires exhibiting an unexpectedly high selectivity for the production of N-hydroxylanilines, through the partial hydrogenation of nitroaromatics. Mechanistic studies reveal that the electron donation from ethylenediamine makes the surface of platinum nanowires highly electron rich. During catalysis, such an interfacial electronic effect makes the catalytic surface favour the adsorption of electron-deficient reactants over electron-rich substrates (that is, N-hydroxylanilines), thus preventing full hydrogenation. More importantly, this interfacial electronic effect, achieved through simple organic modifications, may now be used for the optimization of commercial platinum catalysts.

Coordination compounds as the precursors for preparation of nanosized platinum or platinum-containing mixed-metal catalysts of oxygen reduction reaction

Nanosized mixed-metal platinum-iron, platinum-anganese and platinum-nickel catalysts supported on highly dispersed carbon black are synthesized by using the corresponding metal complexes with the atomic metal ratio of 1:1. The obtained catalysts are characterized by X-ray phase diffraction and scattering analysis, electron dispersion analysis, scanning and transmission electron microscopy. Thin film rotating disk electrode technique was used to study kinetic parameters of the oxygen reduction reaction at these catalysts. It has been demonstrated that electrochemical activity of the prepared catalysts is comparable to that of a commercial E-Tek platinum catalyst. The membrane electrode assembly (MEA) with the synthesized platinum-iron catalyst was tested in a laboratory hydrogen-air fuel cell setup at room temperature. It was shown that the power performance of this MEA was twice better than that of a MEA on the base of a commercial Pt/C E-Tek catalyst.

The Synthesis of Metallic β-Sn Nanostructures for Use as a Novel Pt Catalyst Support and Evaluation of Their Activity Toward Methanol Electrooxidation

This study offers a unique insight into the use of high surface area metallic tin as support material for platinum catalysts for fuel cell application. We have synthesized high surface area metallic β-tin nanostructures (TNSs) in aqueous solutions by novel one-pot process and used it as a platinum catalyst support in methanol electrooxidation reaction. Rigorous study of parameters controlling the size and shape of TNSs was performed, including selected surfactant molecules at various concentrations, tin salts, and the addition of sodium citrate. Rod-shaped particles with a 50-nm diameter and 500-nm length were obtained from solutions of selected surfactant in concentrations of 1–20 mM by sodium borohydride reduction. These particles had a β-Sn crystalline core with a main lattice plane of (101) and were covered by a 4-nm oxide shell. A maximal surface area of 170 m2 g−1 was measured from a sample prepared by using low concentration of sodium dodecyl sulfate (SDS) (1 mM). This sample is composed of nanorods and nano semi-spherical shape tin particles. Addition of sodium citrate, which acts as a Sn2+ ion ligand, yields longer rods. Electrochemical oxidation of methanol on platinum catalyst, supported on metallic Sn nanostructure, exhibits a high activity, which is comparable to commercial carbon-supported platinum catalysts. In situ surface-enhanced Raman (SER), emphasizing the role of surface oxides on the methanol oxidation activity, further studied methanol oxidation on Pt/TNS, Pt/C, and Pt-Sn alloy catalyst.

Iron phthalocyanine and MnOx composite catalysts for microbial fuel cell applications

A low cost iron phthalocyanine (FePc)-MnOx composite catalyst was prepared for the oxygen reduction reaction (ORR) in the cathode of microbial fuel cells (MFCs).The catalysts were characterised using rotating ring disc electrode technique. The n number of electrons transferred, and H2O2 production from ORR was investigated. The FePc–MnOx composite catalyst showed higher ORR reduction current than FePc and Pt in low overpotential region. MFC with composite catalysts on the cathode was tested and compared to Pt and FePc cathodes. The cell performance was evaluated in buffered primary clarifier influent from wastewater treatment plant. The membrane-less single chamber MFC generated more power with composite FePcMnOx/MON air cathodes (143mWm−2) than commercial platinum catalyst (140mWm−2) and unmodified FePc/MON (90mWm−2), which is consistent with the RRDE study.The improvement was due to two mechanisms which abate H2O2 release from the composite. H2O2 is the reactant in two processes: (i) chemical regeneration of MnOx after electro-reduction to Mn2+, and (ii) peroxide undergoing chemical disproportionation to O2 and H2O on an electrochemically aged manganese surface retained in the film. Process (i) has the potential to sustain electrochemical reduction of MnOx at cathode potentials as high as 1.0VRHE.

A Simple Synthesis of an Excellent Oxygen Reduction Catalyst: Nitrogen-Doped, Sharply-Mesoporous Carbon from Magnesium Salts

Any new oxygen reduction catalysts for practical low-temperature fuel cell applications must compete with the commercial platinum catalysts on efficiency and cost. Mesoporous nitrogen-doped carbon (N:C) has emerged as a leading alternative, mostly due to its high surface area, and the promise for low-cost production. While the best mesoporous N:C catalysts in the literature can operate on par with commercial platinum/carbon composites,1 their synthesis is complex and difficult – increasing their cost and rendering them impractical. We present a particularly simple synthesis of N-doped carbon, starting from magnesium salts of nitrogen-containing ligands. Pyrolysis of the salts proceeds by the little-researched mechanism of self-templating – formation of similarly sized MgO nanoparticle cores, which are then washed out with dilute acid, leaving behind a narrow pore size distribution. These carbons have high surface areas (>1400 m2/gr), nitrogen doping levels topping what is required for catalysis (>4%), and most interestingly, a very narrow pore size distribution (ranging from 10 to 20 nm for different carbons). Tested in alkaline ORR catalysis, these carbons compete successfully with commercial platinum-based electrodes, so they are efficient, cheap, and simple to prepare. (1) W. Wei, H. Liang, K. Parvez, X. Zhuang, X. Feng, K. Müllen, Angew. Chem. 2014, 126, 1596.

Self-sustained oscillations of temperature and conversion in a packed bed microreactor during 2-methylpropene (isobutene) hydrogenation

Hydrogenation of 2-methylpropene over commercial platinum catalyst has been studied in a packed bed microreactor. Using common dimensionless criteria and experimental diagnostic the presence of heat and mass transfer limitations has been detected. Analysis of experimental results has pointed to the presence of heat and mass transfer control. Consequently, only a limited set of data under the kinetic control regime could be collected. Self-sustained spontaneous and reproducible oscillations of 2-methylpropene conversion have been observed experimentally under certain conditions. The temperature of the catalyst bed well reflected the oscillatory course of 2-methylpropene conversion. The observed oscillations exhibited exceptionally long periods ranging from 11 to 22h depending on the prevailing space velocity. The appearance of oscillations of the conversion has been ascribed to the complex interaction between the exothermic reaction, heat transfer and a reversible decrease in the catalyst activity. Possible mechanisms of temporary catalyst activity decrease have been proposed.

Combined Nitrogen Precursor Approach to Develop Cobalt-Based Non-Precious Catalysts for Polymer Electrolyte Fuel Cell Cathodes

The cost of the platinum-based catalysts used in polymer electrolyte membrane fuel cells (PEFCs) is estimated to be almost half of the overall fuel cell stack cost under projected conditions of fuel cell vehicle mass production [1]. To reduce this economic constraint, the development of non-platinum group metal (non-PGM) cathode catalysts with high oxygen reduction reaction (ORR) activity is highly desirable. Our group and others have demonstrated immense progress in non-PGM catalyst development, with the specific class of pyrolyzed transition metal-nitrogen-carbon (M-N-C) catalysts achieving high activity [2,3]. In order to realize the successful implementation of these non-PGM catalysts into PEFC systems, the significant issue of operational durability must be addressed. The two most promising M-N-C catalyst technologies are based on either iron or cobalt, with the former conventionally providing enhanced ORR performance, approaching that of commercial platinum catalysts. From a system perspective, however, the presence of iron species in the catalyst layer is highly undesirable. This is owing to the well-known Fenton chemistry, resulting in the formation of highly reactive free-radical species that in turn leads to membrane and/or ionomer decomposition. To address this challenge, we prepared cobalt-based catalysts using the combined-precursor approach recently developed at Los Alamos National Laboratory [4]. This approach utilizes both polyacrylonitrile (PANI) and cyanamide (CM) as nitrogen/carbon precursors that are combined and pyrolyzed with a carbon support and cobalt salt. Individually, both PANI and CM precursors have been previously demonstrated capable of forming highly ORR-active catalysts. Through this approach, we found that the relatively low decomposition temperature (ca. 260°C) of CM allows it to synergistically act as a pore-forming agent and yield high surface-area catalysts. This in turn leads to excellent H2-air fuel cell performance due to the reduced mass transport limitations in the cathode. In this work, Co-CM-PANI-C was formed and found to provide promising activity towards the ORR in acidic electrolyte. Particularly, it was determined that 8.0 wt.% cobalt in the precursor mixture provided optimal ORR activity through half-cell investigation (Figure 1). A half-wave potential of ca. 0.74 V vs.RHE was achieved, with current investigations underway to understand and optimize the structure-performance-durability relationships. These results, along with performance and durability data from both half-cell and MEA evaluation, will be presented at the meeting. Acknowledgements Financial support for this was has been provided by the DOE-EERE through the Fuel Cells Technologies Office and by the Natural Sciences and Engineering Research Council of Canada (NSERC).

Hetro-Atom Doped CNTs As Metal Free Electrocatalyst for Oxygen Reduction Reaction in Alkaline Fuel Cell

Search for eco-friendly sustainable solutions to the alarming energy calamity on both the small and large scale for portable electronic to automobile industry has become one of the most critical challenges on the way to decrease our dependence on traditional fossil fuels based energy sources. In this regard fuel cells provide an alternative solution for clean and green approach. The oxygen reduction reaction (ORR) a half cell reaction taking place at cathode being sluggish in nature requires catalyst to enhance the kinetics. ORR plays a vital role in controlling the performance of a fuel cell. Hence there is a huge demand to develop efficient ORR electrocatalysts for practical applications of the fuel cells. Traditionally, Pt-based electrocatalysts are most suitable for ORR because of their relatively low overpotential and high current density. But the limitation arises because they suffer from serious intermediate tolerance, anode crossover, poor operating stability in an aggressive electrochemical environment. Furthermore, high cost and limited supply hinder wide spread commercialization. This has driven the extensive search for alternative low-cost and high-performance ORR electrocatalysts. Here, we report a facile one-step synthesis of nitrogen-, boron-doped and nitrogen & boron co-doped carbon nanotubes (CNTs) by pyrolysis and used as platinum-free cathode catalyst in direct methanol fuel cell (DMFC). Doped CNTs show excellent catalytic activity and methanol tolerance towards ORR which prompted us to study its fuel cell application. Doped CNTs used as cathode catalyst in DMFC shows comparable performance with the reported results based on state of art commercial platinum catalyst. Overall, the excellent methanol tolerance and good durability of doped CNTs based DMFC suggest a potential to replace platinum for making fuel-cell technology commercially viable.

Influence of the relative volumes between catalyst and Nafion ionomer in the catalyst layer efficiency

Over the years, studies have analyzed the composition of the catalyst layer using commercial platinum catalyst, supported on Vulcan XC72 with 20% of metal loading (Pt/C 20%Mw), and found that values between 20 and 40% of Nafion ionomer related to the mass of the catalyst layer (% NIW) have resulted in more efficient electrodes for PEMFC. Recent studies with catalysts synthesized on Vulcan XC72 resulted in 59% NIW as the best formulation. In this work, the commercial and the synthesized Pt/C 20%Mw catalyst were evaluated by Gas Pycnometry, Gas Adsorption (through BET and BJH), and Mercury Intrusion Porosimetry. The results showed volumetric differences between the Vulcan XC72 used in commercial catalyst and the Vulcan XC72 commercially available for synthesis (as purchased). These differences impair the synthesized catalyst in comparison with the commercial one. Therefore, the relationship between the quantities of catalysts and Nafion ionomer on the catalyst layers must be calculated as a function of the catalysts volumes.

Palladium nanoparticles supported on nitrogen-doped carbon spheres as enhanced catalyst for ethanol electro-oxidation

In this paper, nitrogen-doped carbon spheres (NCSs) were prepared as a new catalyst support for ethanol electro-oxidation through carbonization of poly(o-phenylenediamine) spheres. The NCS-supported palladium nanocatalyst exhibited higher current density and better stable life for ethanol electro-oxidation in alkaline media than palladium catalysts supported on activated carbon and nitrogen-doped carbon nanotubes. The catalytic current of the palladium/NCS composite was even comparable to commercial platinum catalyst (40wt% Pt loading).

A novel Rh–Ir electrocatalyst for the oxygen reduction reaction and the hydrogen and methanol oxidation reactions

A novel Rh–Ir based material was synthesized by pyrolysis of an Ir4(CO)12/Rh6(CO)16 mixture in a reductive (H2) atmosphere. The material was characterized by FTIR spectroscopy, X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy, and was evaluated as electrocatalyst for oxygen reduction and hydrogen and methanol oxidation by rotating disk electrode measurements. The bimetallic material shows a high catalytic activity for the oxygen reduction reaction and is also capable to carry out the hydrogen oxidation reaction even in the presence of carbon monoxide in different concentrations (100 ppm and 0.5%), in contrast with commercial platinum catalysts, which become easily deactivated by CO. The activity of the catalyst for methanol oxidation is acceptable but still low in comparison with Pt–Ru. The results show that the new bimetallic catalyst is a potential candidate to be evaluated as both cathode and anode in a reforming hydrogen PEMFC, and as an anode in a direct methanol fuel cell.

Investigation of tungsten carbide supported Pd or Pt as anode catalysts for PEM fuel cells

In this contribution, we present results of electrochemical characterization of prepared tungsten carbide supported palladium and platinum and Vulcan XC-72 supported palladium. These catalysts were employed as anode catalysts in PEMFC and results are compared to commercial platinum catalyst. Platinum seems to be irreplaceable as a proton exchange membrane fuel cell (PEMFC) catalyst for both the anode and the cathode, yet the high price and limited natural resources are holding back the commercialization of the PEMFCs. Tungsten carbide is recognized as promising catalyst support having the best conductivity among interstitial carbides. Higher natural resources and significantly lower price make palladium good candidate for replacement of the platinum catalyst. The presented results show that all prepared catalysts are very active for the hydrogen oxidation reaction. Linear sweep voltammetry curves of Pd/C and Pd/WC show existence of peaks at 0.07 V vs. RHE, which is assigned to absorbed hydrogen. H2|Pd/WC|Nafion117|Pt/C|O2 fuel cell has almost the same efficiency and similar power output as commercial platinum catalyst.