AN INTERESTING ALTERNATIVE TO H2-FUELED PEMFC FOR PORTABLE AND MOBILE APPLICATION IS THE USE OF ETHANOL AS A FUEL (DEFC) [1]. MANY STUDIES HAVE POINTED PT-SN/C AS THE BEST ELECTROCATALYST FOR ETHANOL ELECTRO-OXIDATION (EOR) IN ACID ENVIRONMENT. HOWEVER, THESE KINDS OF ALLOYS USUALLY SHOW RELATIVELY LOW SELECTIVITY FOR CO2 FORMATION COMPARED WITH PT ALONE [2]. ZHU ET AL. [3] SYNTHESIZED PT-SNO2 AND PTSN ALLOY CATALYST. THE ANALYSIS OF THE PRODUCTS SHOWS THAT ADDITION OF SNO2 ENHANCED THE TOTAL OXIDATION TO CO2.IN THIS WORK, WE SYNTHESIZED SNO2 BY AN EX SITU METHOD AND MADE A BINARY CATALYST BY ADDING A TIN OXIDE TO PT AND ITS PERFORMANCE COMPARED WITH PT-SN. PT-SNO2 AND PT-SN CATALYSTS SUPPORTED ON CARBON WERE SYNTHESIZED BY A MODIFIED POLYOL METHOD. THE XRD ANALYSIS SHOWED THE ALLOY CATALYST WAS SYNTHESIZED. ELECTROCHEMICAL TESTS SUCH AS CV,LSV, CHORNOAMPEROMETRY AND EIS WERE PERFORMED FOR TWO CATALYSTS. THE CV RESULTS INDICATE THAT THE ONSET POTENTIAL OF TWO CATALYSTS WAS SAME BUT THE RATIO OF IF/IB (CO2 TOLERANCE) FOR PT-SNO2 WAS GREATER THAN PT-SN. THE EIS TECHNIQUE WAS USED TO INVESTIGATE THE CATALYTIC ACTIVITY FOR THE CO OXIDATION AND PT-SNO2 HAVE A BETER TOLERANCE TO CO2.

THERE ARE SEVERAL WAYS TO PRODUCE HYDROGEN INCLUDING HYDROLYSIS, THERMAL CATALYSIS AND THERMOCHEMICAL, PHOTOCATALYSIS, PHOTOELECTROCATALYSIS, STEAM REFORMING, GASIFICATION AND ELECTROLYSIS. IN THE ELECTROCHEMICAL PRODUCTION OF HYDROGEN, PLATINUM (PT) IS AN EXCELLENT ELECTRODE FOR HYDROGEN GENERATION, BUT IT IS EXPENSIVE AND ITS PRESENT RESOURCE IS VERY LIMIT. THEREFORE WE SHOULD LOOK FOR A SUITABLE ALTERNATIVE TO PT. THERE ARE VERY RARE REPORT ON USING METAL- ORGANIC FRAMEWORK (MOF) AS ELECTROCATALYST FOR HYDROGEN EVOLUTION REACTION (HER). IN THIS STUDY CUBDCMOF WAS USED AS A HER ELECTROCATALYST IN CARBON PASTE ELECTRODE (CPE). THE PERFORMANCE OF THE PROPOSED MODIFIED CPE FOR ELECTROCHEMICAL HYDROGEN PRODUCTION WAS STUDIED BY CYCLIC VOLTAMMETRY, LINEAR SWEEP VOLTAMMETRY (LSV), ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY (EIS) AND CHRONOAMPEROMETRY TECHNIQUES. FOR OPTIMIZATION OF CONDITIONS SOME PARAMETERS INCLUDING CATALYST PERCENT, PASTE BINDER AMOUNT AND PH WAS CHANGED AND THEIR EFFECT ON HER WAS EVALUATED. THE BEST PERFORMANCE WAS OBTAINED FOR 25% CATALYST, 30% BINDER AND 2 M H2SO4 SOLUTION. IN ADDITION, A PROMISINGRESULT SHOWED THAT BY APPLYING SUCCESSIVE CVS THE CURRENT DENSITY INCREASES.

AN ELECTROCHEMICAL APPROACH TO NANOSTRUCTURED NI/PDNI CATALYST DESIGN USING THE ELECTRODEPOSITION PROCESS AND GALVANIC REPLACEMENT TECHNIQUE IS PRESENTED. THE PROCEDURE CONSISTED OF THE ELECTRODEPOSITION OF NI-ZN (TOP LAYER) ON THE NI (UNDER LAYER) COATING, WITH SUBSEQUENT REPLACEMENT OF THE ZINC BY PALLADIUM AT OPEN CIRCUIT IN A PALLADIUM CONTAINING ALKALINE SOLUTION. THE SURFACE MORPHOLOGIES AND COMPOSITIONS OF COATING BEFORE AND AFTER GALVANIC REPLACEMENT WERE DETERMINED BY ENERGY DISPERSIVE X-RAY AND SCANNING ELECTRON MICROSCOPY (SEM) TECHNIQUES. THE SEM RESULTS SHOWED THAT THE NI/PDNI COATINGS WERE POROUS, AND COMPOSED OF DISCRETE PD NANOPARTICLES WITH THE CRYSTALLITE SIZE OF ABOUT 58 NM. THE ELECTRO-CATALYTIC ACTIVITY OF NI/PDNI ELECTRODES TOWARD ELECTROOXIDATION OF ETHANOL WAS STUDIED BY USING CYCLIC VOLTAMMETRY AND ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY TECHNIQUES. THE RESULTS SHOWED THAT NI/PD-NI CATALYST HAD A HIGHER ELECTRO-CATALYTIC ACTIVITY FOR ETHANOL ELECTROOXIDATION THAN FLAT PD AND SMOOTH NI, RESPECTIVELY, DUE TO THE HIGH SURFACE ARE AND THE SYNERGISTIC EFFECTS OF PD AND NI. THEREFORE, THE NI/PD-NI CATALYSTS CAN BE POTENTIAL ANODE CATALYSTS FOR THE DIRECT ETHANOL FUEL CELL.

THE CORE- SHELL STRUCTURE OF CATALYST IS ONE OF THE EFFECTIVE WAYS THAT NOT ONLY REDUCED PT LOADING BUT ALSO RAISED PT UTILIZATION FOR ORR ON ELECTRODE [1-3]. IN THIS RESEARCH, BIMETALLIC ELECTROCATALYST (RU@PT) WITH CORE- SHELL STRUCTURE WERE SYNTHESIZED BY USING THE IMPREGNATION WITH HYDROTHERMAL METHOD STEP BY STEP AND WERE CHARACTERIZED BY PHYSICAL AND ELECTROCHEMICAL TECHNIQUES. PHYSICAL TECHNIQUES (XRD, TEM AND ICP) INDICATE THAT THE RU AND PT WERE SUCCESSFULLY REDUCED ON VULCAN WITH DIFFERENT MOLAR RATIO (1:1, 2:1 AND 3:1 PT:RU). THE ELECTROCHEMICAL TECHNIQUES WERE DONE IN THREE ELECTRODE SYSTEM (LSV, CV, IES AND CHRONOAMPEROMETERY) AND SINGLE CELL. THE RESULTS OF HALF-CELL STUDIES ILLUSTRATED THAT AMONG 1:1, 2:1 AND 3:1 FOR ORR, 1:1 OF PT: RUMOLAR RATIO HAD THE BEST PERFORMANCE, THERE FOR, THE MEA WAS PREPARED BY USING THIS ELECTROCATALYST IN CATHODE AND COMMERCIAL PT/C AS ANODE. ELECTRODE FABRICATION IS SIMILAR TO PREVIOUSE WORK [4]. THE XRD PATTERNS SHOW THAT THE SIZE OF ELECTROCATALYST PARTICLE WAS NANOMETER. MOREOVER, THE TEM IMAGE INDICATES THE GOOD DISPERSION OF CATALYST IN 11. BETTER PERFORMANCE OF 1:1 MOLAR RATIO CAN ATTRIBUTED TO WELL DISPERSION OF CATALYST ON VULCAN AND CONSEQUENTLY INCREASED THREE PHASE ZONE. THE ELECTROCHEMICAL RESULTS EMPHASIS THIS IDEA (FIG. 3 AND 4). AS IT CAN SEE IN TABLE 1, EXCHANGE CURRENT DENSITY, ELECTROACTIVE SURFACE AREA AND CHARGE TRANSFER RESISTANCE OF 11(1:1 OF PT: RU) ARE THE BEST. THE ELECTRODE AREA OF MEA IS 5 CM2, AND THE CATALYST LOADING IS 0.3 MG.CM-2. THE N-112 WAS USED AS MEMBRANE AND ACTIVATION PROCESS WAS 0.6V AT 10H. THE POLARIZATION CURVE AND POWER DENSITY OF SINGLE CELL WERE OBTAINED (FIG. 5). MAXIMUM POWER DENSITY OF THIS CELL IS 547 MW.CM-2. THIS RESULT IS COMPARABLE TO OTHER REPORTED [1-3]. BY APPLIED DIFFERENT GAS PRESSURE AND ANODE HUMIDIFICATION CAN ACHIEVED THE BETTER RESULTS.

EXTENSIVE RESEARCH AND DEVELOPMENT EFFORTS ARE BEING UNDER TAKEN IN RECENT YEAR IN THE FIELD OF PEM FUEL CELL (PEMFC) SYSTEMS TO MAKE THEM COMMERCIALLY VIABLE. IN PROTON EXCHANGE MEMBRANE FUEL CELLS, STABILITY AND DURABILITY ARE IMPORTANT OBJECTS FOR COMMERCIALIZATION. IT IS WELL-KNOWN THAT CATALYST DEGRADATION AND CARBON-SUPPORT CORROSION ARE THE MAIN FACTORS REDUCING STABILITY, AND USING PT NANOCATALYST ON CARBON NANOTUBE SUPPORTS INSTEAD OF PT/C INCREASE STABILITY AND DURABILITY AFTER LONG-TERM AGING. IN THIS WORK, A HYDROTHERMAL METHOD WAS EMPLOYED TO PREPARE PT NANOPARTICLES DISPERSED HIGHLY ON MULTIWALLED CARBON NANOTUBES WITH 19.4 WT. % PT. MEMBRANE ELECTRODE ASSEMBLES (MEAS) FROM TOW CATALYST FABRICATED WITH THIN FILM METHOD. IN FUEL CELL TEST STATION, THE POLARIZATION, AC IMPEDANCE AND CYCLIC VOLTAMMETRY EXPERIMENT OF MEAS AND ALSO ADT TEST WAS DONE. THE PT/C CATALYST SHOWED NO ACTIVITY IN FUEL CELL TESTING AFTER 2000 POTENTIAL CYCLES DUE TO SEVERE CARBON CORROSION, PT DISSOLUTION, AND CATALYST PARTICLE SINTERING. CONVERSELY, THE PT/MWCNT CATALYST SHOWED BETTER ELECTROCHEMICALLY ACTIVE SURFACE AREA AND ALSO DURABILITY AFTER A POTENTIAL CYCLING. THE ANALYSIS OF AC IMPEDANCE SPECTRA ASSOCIATED REVEALED THAT THE PRESENCE OF CNTS SIGNIFICANTLY REDUCED INCREASING OF ACTIVATION RESISTANCES. THE PERFORMANCE OF FRESH MEA FABRICATED FROM PT/C WAS BETTER THAN FRESH PT/MWCNT MEA, BUT AFTER ADT TEST HAD MORE REDUCE. LOSS ELECTROCHEMICAL ACTIVE SURFACE AREA OF PT/C CATALYST WAS HIGHER THAN PT/MWCNT CATALYST DUE TO MORE CATALYST PARTICLE SINTERING.

PALLADIUM (PD) IS ONE OF THE MOST FREQUENTLY EMPLOYED ELECTROCATALYST MATERIALS FOR FORMALDEHYDE OXIDATION [1]. PD NANOPARTICLES CATALYZE FORMALDEHYDE ELECTROOXIDATION VIA DIRECT PATHWAY AND EXHIBIT GREAT RESISTANCE TO CO-LIKE POISONING INTERMEDIATES [2]. TO IMPROVE THE CATALYTIC ACTIVITY OF THE PD NANOPARTICLES, THEY ARE DEPOSITED ON VARIOUS CONDUCTIVE MATERIALS SUCH AS CARBON SUPPORTS. MULTI WALL CARBON NANOTUBE (MWCNT) IS ONE OF THE MOST WIDELY USED SUPPORTS IN FUEL CELLS. MWCNT CAN ENHANCE ELECTRON TRANSFER BETWEEN ELECTROACTIVE SPECIES AND ELECTRODES AND IMPROVE REVERSIBILITY OF ELECTROCHEMICAL REACTION [3]. IN THIS RESEARCH, PD NANOPARTICLES ARE DEPOSITED ON MWCNT BY CHEMICAL REACTION VIA SODIUM BOROHYDRIDE REDUCING AGENT. MWCNT-SUPPORTED PD (PD/MWCNT) WAS DECORATED ON CARBON CERAMIC ELECTRODE (PD/MWCNT/CCE) AND USED AS ELECTROCATALYST FOR OXIDATION OF FORMALDEHYDE IN ALKALINE MEDIA. X-RAY DIFFRACTION (XRD) AND SCANNING ELECTRON MICROSCOPY (SEM) ANALYSES WERE PERFORMED TO CHARACTERIZE THE NANOSTRUCTURE OF PD/MWCNT. ELECTROCHEMICAL STUDIES INCLUDING CYCLIC VOLTAMMETRY AND CHRONOAMPEROMETRY WERE USED TO STUDY ELECTROCHEMICAL PROPERTIES OF OBTAINED ELECTROCATALYST. THE EFFECTS OF SOME EXPERIMENTAL FACTORS SUCH AS ELECTROCATALYST DEPOSITION VOLUME ON CCE, FORMALDEHYDE AND NAOH CONCENTRATION, SCAN RATE, THE UPPER LIMIT OF POTENTIAL SCANNING REGION AND LONG-TERM STABILITY OF ELECTRODE WERE INVESTIGATED. IT WAS FOUND THAT PD/MWCNT/CCE WAS CATALYTICALLY MORE ACTIVE THAN PD NANOPARTICLES DECORATED ON CCE WITHOUT ANY SUPPORT. ON THE OTHER HAND, THE PD/MWCNT/CCE CATALYST HAS SATISFACTORY STABILITY AND REPRODUCIBILITY FOR ELECTROOXIDATION OF FORMALDEHYDE WHEN STORED IN AMBIENT CONDITIONS AND IMPROVE CATALYTIC ACTIVITY IN CONTINUES CYCLING MAKES IT MORE ATTRACTIVE FOR FUEL CELL APPLICATIONS.

IN THE PRESENT STUDY, PD (DBA)2 ELECTROCATALYST HAS BEEN USED FOR THE ELECTROOXIDATION OF DIFFERENT ALCOHOLS (ETHANOL, METHANOL, ETHYLENE GLYCOL AND GLYCEROL) IN ALKALINE MEDIA. THE MORPHOLOGY AND PHASE OF THE CATALYST ARE ANALYZED BY SCANNING ELECTRON MICROSCOPE (SEM) AND X-RAY ENERGY DISPERSION SPECTROSCOPY (EDS). THE ACTIVITY AND STABILITY OF THE PD (DBA)2 CATALYST ARE ASSESSED FOR THE ELECTROOXIDATION OF ALCOHOLS IN ALKALINE MEDIUM USING CYCLIC VOLTAMMETRY AND ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY (EIS). THE RESULTS SHOW THAT PD (DBA)2 REPRESENT PROMISING CANDIDATE FOR THE ELECTROCATALYTIC OXIDATION OF ALCOHOLS. THE ACTIVITY ORDER OF ALCOHOL OXIDATION ON PD (DBA)2 IS ETHANOL (ET)>ETHYLENE GLYCOL (EG)>GLYCEROL (GLY)>METHANOL (ME). ETHANOL SHOWS HIGHEST ELECTROCATALYST ACTIVITY AND EXCELLENT STABILITY.

CARBON-SUPPORTED PD–CO ALLOY ELECTROCATALYST WERE SYNTHESIZED AND CHARACTERIZED FOR THE PURPOSE OF THE FUEL CELL CATHODE OXYGEN REDUCTION REACTION (ORR). AN IMPREGNATION METHOD WAS EMPLOYED FOR THE SYNTHESIS, IN WHICH EG WAS USED AS A REDUCING AGENT. THE SYNTHESIZED CATALYST WAS CHARACTERIZED IN TERMS OF CATALYTIC ACTIVITY BY ELECTROCHEMICAL MEASUREMENTS.SURFACE CYCLIC VOLTAMMETRY WAS USED TO CONFIRM THE FORMATION OF THE PD–CO ALLOY. IN ORDER TO IMPROVE ACTIVITY AND STABILITY, THE CATALYST WAS HEAT-TREATED IN THE TEMPERATURE OF 300OC. THE CATALYZED ORR KINETICS WERE ALSO STUDIED USING THE ROTATING DISK ELECTRODE (RDE) METHOD. ELECTROCATALYTIC ORR ACTIVITY WAS ALSO EXAMINED IN AN ACIDIC SOLUTION CONTAINING METHANOL. THE RESULTS SHOWED THAT THE SYNTHESIZED PD–CO/C CATALYST HAS METHANOL TOLERANT CAPABILITIES.