Methanol oxidation on MoO 3 promoted Pt/C electrocatalyst (original) (raw)
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Nano PtCuO particles were deposited on Vulcan XC-72R carbon black using the impregnation and microwave irradiation methods. The prepared catalysts were characterized by XRD, TEM and EDX analyses. TEM images indicated that the microwave method provides homogeneously distributed catalyst particles in smaller size, compared to the one prepared by the impregnation method. The electrocatalytic activity of Pt‒CuO/C electrocatalysts was investigated to oxidize methanol in 0.5 M H2SO4 solution by applying cyclic voltammetry and chronoamperometry techniques. The oxidation current density of Pt‒CuO/C electrocatalyst, prepared by the microwave method, showed two folds increment with a potential shift in the negative direction by 69 and 36 mV at the first and second oxidation peaks, respectively, relative to those at the catalyst prepared by the impregnation method. The effect of varying methanol concentration on the resulting oxidation current density of Pt‒ CuO/C electrocatalysts was studied. Some kinetic information about the reaction order with respect to methanol and Tafel slope values was calculated. Slower current density decay was observed in the chronoamperogram of Pt‒CuO/C electrocatalyst, prepared by the microwave method, reflecting a lower degree of surface poisoning.
Journal of Power Sources
The present study is focused in the use of core–shell molybdenum substrates as supports for Pt electrocatalysts. These substrates are prepared by the carbothermal-reduction method and present a core–shell structure, with a reduced-Mo core (Mo2C, MoO2 and/or Mo0) and a MoO3shell. Kinetic and mechanistic studies were performed through potentiodynamic and potentiostatic experiments for carbon monoxide and methanol oxidation reactions on Pt/X@MoO3/C (X = Mo2C, MoO2, Mo0) catalysts in an intermediate temperature range (20 < T < 70 °C). Results reveal the promoter effect and the great stability of Mo-carbide based substrates for both reactions in the temperature range studied. Carbon monoxide and methanol oxidation on Pt/X@MoO3/C are enhanced by a facile oxygenated species formation, better dispersion of the active phase and electronic effects. It is concluded that the best catalyst performance during the methanol oxidation reaction was obtained with the substrate that contains only...
Effect of functionalized carbon as Pt electrocatalyst support on the methanol oxidation reaction
Applied Catalysis B: Environmental, 2011
a b s t r a c t FTIRS and XPS spectra showed that after oxidative treatments using H 2 SO 4 + HNO 3 and HNO 3 solutions the Vulcan XC-72R carbon support has been found to be more hydrophilic and richer in oxygen-containing functional groups. Consequently, the Pt electrocatalyst prepared on those functionalized carbon materials further to having good dispersion of metal presented a significant improvement of the electrocatalytic activity due to the synergistic effect between the metal nanoparticles and oxygenated groups on functionalized carbon.
iranian journal of catalysis, 2017
The impregnation method was used to synthesize Pt and Pt3Co supported on MWCNTs applying NaBH4 as the reducing agent. The structure, morphology, and chemical composition of the electrocatalysts were characterized through SEM, XRD, and EDX. X-ray diffraction showed a good crystallinity of the supported Pt nanoparticles on the composites and showed the formation of Pt3Co alloy. The SEM images revealed that the particles of Pt3Co were deposited uniformly on the surface of MWCNT with a diameter of 10 nm. EDX analysis confirmed the surface segregation of Co and Pt occurred (1:3 surface atomic ratio Pt-Co) for the Pt3Co/MWCNT nanocomposite. The Pt3Co/MWCNTs and Pt/MWCNTs electrocatalysts’ electrochemical performance was assessed against the methanol oxidation reaction (MOR) in 0.5 M H2SO4 solution using the chronoamperometry (CA) and the cyclic voltammetry (CV) methods. The minimum onset potential and the largest oxidation current density were obtained at Pt3Co/MWCNTs electrocatalyst. The...
Journal of Power Sources, 2006
Acetate-stabilized Pt nanoparticles supported on carbon were prepared by a microwave heating polyol method, in which a small amount of sodium acetate solution was added as a stabilizing agent in the synthesis solution. The Pt/C catalysts were characterized by energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the Pt nanoparticles were small and uniform in size, and highly dispersed on XC-72 carbon supports. The mean size of the Pt particles was 5.1, 4.3, 3.5 and 2.8 nm, respectively, correspondingly for adding 0, 0.1, 0.3 and 0.5 mL of 1.0 M sodium acetate solution in 50 mL of the synthesis solution. The effects of the amount of acetate solution added on the Pt particle size and size distribution were investigated. The electrochemical measurements demonstrated that the Pt/C catalysts prepared in this way exhibited a much higher electrocatalytic activity for methanol electro-oxidation than a comparative Pt/C catalyst prepared without adding acetate.
Pt and PtRu nanoparticles deposited on single-wall carbon nanotubes for methanol electro-oxidation
Journal of Power Sources, 2007
Platinum (Pt) and platinum-ruthenium (PtRu) nanoparticles supported on Vulcan XC-72 carbon and single-wall carbon nanotubes (SWCNT) are prepared by a microwave-assisted polyol process. The catalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The PtRu nanoparticles, which are uniformly dispersed on carbon, have diameters of 2-6 nm. All the PtRu/C catalysts display the characteristic diffraction peaks of a face centred cubic Pt structure, excepting that the 2θ values are shifted to slightly higher values. The results from XPS analysis reveal that the catalysts contain mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV) and Ru(IV). The electrooxidation of methanol is studied by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. Both PtRu/C catalysts have high and more durable electrocatalytic activities for methanol oxidation than a comparative Pt/C catalyst. Preliminary data from a single direct methanol fuel cell using the SWCNT supported PtRu alloy as the anode catalyst delivers high power density.
Methanol Electro-Oxidation on Bimetallic PtMo/C Catalysts and Pt/C - Mo/C Mechanical Mixtures
International Journal of Electrochemical Science, 2016
The role of molybdenum in carbon-supported Pt-Mo electrocatalysts was studied with the aim of obtaining active materials to be used as anodes in the methanol electro-oxidation reaction. The catalysts were synthesized by the thermolysis of Mo and Pt carbonyls. Two series were obtained: bimetallic PtMo/C, and Pt/C plus Mo/C mechanical mixtures. The Mo content was changed, with the atomic ratio ranging from 0.0 to 1.0. XRD and XPS analyses of the fresh materials indicated the presence of Pt 0 and molybdenum oxides (MoO x). XRD of Mo/C treated electrochemically at constant potential in H 2 SO 4 confirmed the formation of molybdenum bronzes with different protonation degrees (H x MoO 3 0.3 < x < 2). Cyclic voltammetry indicated that Mo/C does not present the capacity to oxidize methanol nor the intermediate species, but it did show promoter behavior. In the PtMo/C series, low molybdenum contents present the maximum promoting effect on methanol electrooxidation, as evidenced by lower onset potentials for the methanol oxidation reaction with respect to the Pt/C catalyst. Similar results were registered by the mechanical mixtures, where the Pt sites are separated from the molybdenum bronzes, suggesting that Pt poisoned sites, caused by methanol electro-adsorption, are cleaned by the interaction with molybdenum bronzes (H x MoO 3) through a process of surface diffusion of oxygen-containing species.
International Journal of Hydrogen Energy, 2010
Pt catalyst supported on Vulcan XC-72R containing 5 wt% NiO (Pt/NiO-C) showed larger electrochemical active surface area and higher electrochemical activity for methanol oxidation than Pt catalyst supported on Vulcan XC-72R using polyol method without NiO addition. Prepared Pt/NiO-C electrocatalyst was heat-treated at four temperatures (200, 400, 600, and 800 C) in flowing N 2. X-ray diffraction and temperature-programmed desorption results indicated that NiO was reduced to Ni in inert N 2 during heat-treatments at temperatures above or equal to 400 C, while oxygen from NiO reacted with carbon support due to the catalytic effect of Pt. The reduced Ni formed an alloy with Pt, which, according to the X-ray photoelectron spectroscopy data, resulted in a shift to a lower binding energy of Pt 4f electrons. The Pt/NiO-C electrocatalyst heat-treated at 400 C showed the best activity in methanol oxidation due to the change in Pt electronic structure by Ni and the minimal aggregation of Pt particles.
Catalysis Today, 2020
In this work, anodic electrocatalyst (20%wt of metal loading) as PtCo nanoparticles (atomic ratio of 48:52) on micro/nano-structured pyrolytic carbon (MNC) was synthesized by sequential impregnation method and chemical reduction route using citric acid and Ar-H 2 static atmosphere. MNC sample was synthesized via nanocasting process with anhydrous pyrolysis at 800°C using SBA-15 as hard template and refined sugar as carbon source. SBA-15 was prepared via sol gel using pluronic P-123 as surfactant and tetraethoxysilane as silica precursor. The prepared materials were characterized by means of N 2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and high resolution transmission electron microscopy. The performance of PtCo/MNC for methanol oxidation reaction (MOR) was measured by cyclic voltammetry, chronoamperometry. The electrochemical characterization techniques revealed that the mass activity of PtCo/ MNC and the commercial electrocatalyst Pt/C (20%wt of Pt loading) at 20 cycles were 481 and 372 mA/mg Pt respectively as well as the resistance to the accumulation intermediate carbonaceous species (methoxy, aldehyde, formaldehyde and carbon monoxide) denoted by the ratio I f /I b for these catalysts were 1.30 and 0.76 respectively. PtCo/MNC exhibit better electrocatalytic performance, electrochemical stability and best resistance to carbonaceous intermediates species in the electro-oxidation of methanol.
Applied Catalysis B: Environmental, 2013
A bimetallic Pt-Cu carbon-supported catalyst (Pt(Cu)/C) has been prepared by a room temperature twostep procedure involving the chemical reduction of Cu ions by sodium borohydride in the presence of Vulcan XC72R carbon powder, followed by the partial galvanic replacement of Cu particle layers by Pt, upon immersion in a chloroplatinate solution. The characterization of the Pt(Cu)/C catalyst by XRD has proven the formation of a Pt-Cu alloy while cyclic voltammetry in deaerated acid revealed similar characteristics to those of pure Pt. These two findings point to the existence of Pt-rich outer layers and a Pt-Cu core. The electrocatalytic activity of the bimetallic Pt(Cu)/C catalyst towards methanol oxidation is comparable to or better than that of a commercial 20% Pt Vulcan XC72R catalyst (when assessed by voltammetric or prolonged chronoamperometric experiments respectively). This is attributed to the effect of Cu on CO poison adsorption and removal from Pt. Moreover, related to the same effect but also to the reduced Pt loading of the mixed Pt-Cu particles, the specific mass activity of the prepared catalyst is superior to that of the commercial catalyst. (S. Sotiropoulos). et al. applied the technique to the partial replacement of Ti surface layers or Cu and Pb polylayers by Pt, resulting in the latter case in Pt shell-Cu (or Pb) core particles, denoted as Pt(Cu) or Pt(Pb). Sotiropoulos and co-workers expanded the method to the replacement of Pb, Cu, Fe, Co, Ni polylayers by Pt and Au .