Effect of preparation conditions on the performance of nano Pt‒CuO/C electrocatalysts for methanol electro-oxidation (original) (raw)
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Methanol oxidation on MoO 3 promoted Pt/C electrocatalyst
2011
MoO 3 is incorporated into Vulcan carbon XC-72R by solidestate reaction under intermittent microwave heating (IMH) method. The Pt nanoparticles are dispersed by microwaveassisted polyol process. The physicochemical characterization reveals that MoO 3 and Pt nanoparticles are evenly deposited on Vulcan carbon XC-72R. The non-conducting MoO 3 is electrochemically reduced to nonstoichiometric and electroconductive hydrogen molybdenum bronze (H x MoO 3) in acidic solution. The peak current for methanol electrooxidation is about 128% higher on Pt-MoO 3 /C electrode than Pt-Ru/C electrode. Also, there is a significant increase in the electrode response toward stability test which can be attributed to hydrogen molybdenum bronze phase and its direct role in the conversion of CO to CO 2. Intermittent microwave heating method is effective for incorporating oxide materials in Vulcan XC-72R in a short span of time which is evidenced by the formation of hydrogen molybdenum bronze phase during the CV measurements.
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 .
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...
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.
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.
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.
Journal of Power Sources, 2006
The organic sol method for preparing ultrafine transition metal colloid particles reported for the first time by Bonnemann et al. [H. Bonnemann, W. Brijoux, R. Brinkmann, E. Dinjus, T. Jouen, B. Korall, Angew. Chem. Int. Ed. Engl., 30 (1991) 1312] has been improved in this paper. The improved organic sol method uses SnCl 2 as the reductant and methanol as the organic solvent. Thus, this method is very simple and inexpensive. It was found that the average size of the Pt particles in the Pt/C catalysts can be controlled by adjusting the evaporating temperature of the solvent. Therefore, the Pt/C catalysts prepared by the same method are suitable for evaluating the size effect of the Pt particles on electrocatalytic performance for methanol oxidation. The results of the X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that when the evaporating temperatures of the solvent are 65, 60, 50, 40, and 30 • C, the average sizes of the Pt particles in the Pt/C catalysts prepared are: 2.2, 3.2, 3.8, 4.3, and 4.8 nm, respectively. The X-ray photoelectron spectroscopic (XPS) results demonstrated that the small Pt particles are easily oxidized and the decomposition/adsorption of methanol cannot proceed on the surfaces of Pt oxides. Thus, the Pt/C catalyst with small Pt particles has a low electrocatalytic activity for methanol oxidation. The Pt/C catalyst with a large average size of the Pt particles also possesses a small electrochemically active surface area. Therefore, only the Pt/C catalyst with a middle average size of Pt particles, such as 3.8 nm exhibited optimal electrocatalytic performance for methanol oxidation. Because the Pt/C catalysts with the different particle sizes were prepared with the same method, the size effect on the electrocatalytic performance of the catalysts could be reliably investigated.
Journal of the Serbian Chemical Society, 2019
A binary metal nanocatalyst of platinum and copper was synthesized using a facile solvothermal process (polyol method). The synthesized catalyst was characterized using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electro-chemical performance of the synthesized carbon supported binary metal catalyst , Pt-Cu/С, toward methanol oxidation reaction was checked and then compared with the commercial Pt/C (ETEK) catalyst, using cyclic voltammetry and chronoamperometric techniques. The Pt-Cu/C catalyst was found to be cubic in shape with indentations on the particle surface, having platinum to copper atomic composition of 4:1, i.e., (Pt 4 Cu). The peak current density for Pt-Cu/C catalyst recorded as 2.3 mA cm-2 at 0.7 V (vs Ag/AgCl) and 50 mV s-1 , was two times higher than the current density of the commercially available Pt/C catalyst (1.16 mA cm-2 at 0.76 V). Moreover, the Pt-Cu/C catalyst was found to be more durable than the commercial Pt/C catalyst, as the Pt-Cu/C retained 89 % of its initial current density, while the commercial Pt/C catalyst retained 65 % of its initial current density after 300 potential cycles.
Pt/C nanocatalysts for methanol electrooxidation prepared by water-in-oil microemulsion method
Journal of Solid State Electrochemistry, 2016
Pt nanoparticles supported on Vulcan XC-72R were synthesized by water-in-oil microemulsion method. By incorporating different amounts of HCl as a capping agent in the precursor-containing water phase, nanoparticle shape was varied. Influencing the growth of certain facets leads to the changes of the particle shape depending on the preferential facets. As a result, nanoparticles exhibit some of the electrochemical features typical for single crystals. Commonly employed synthesis procedure for water-in-oil microemulsion method was altered with the addition of catalyst support in the system and changing the catalyst cleaning steps. Prepared catalysts were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and electrochemical methods. Activity and stability for methanol oxidation reaction (MOR), a structure-sensitive reaction, were tested. Electrochemical results reveal the influence of particle size, shape and exposed facets on the electrochemical processes. TEM investigations confirm electrochemical findings, while TGA verifies Pt loading in catalyst powder. Based on the results, optimal HCl concentration for cubic particle formation is determined, and structural effect on MOR activity and stability was tested. Cuboidal NPs show very good reaction activity and fair stability under applied experimental conditions.
Portugaliae Electrochimica Acta, 2009
PtRu/C electrocatalysts were prepared by hydrothermal carbonization process using starch as carbon sources and reducing agents and platinum and ruthenium salts as catalysts of carbonization process and metals source. pH of the reaction medium was adjusted using KOH or TPAOH (tetrapropylammonium hydroxide). The obtained PtRu/C electrocatalysts were characterized by SEM/EDX, TGA, XRD and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry and chronoamperometry. The PtRu/C electrocatalyst prepared using TPAOH was more active for methanol electro-oxidation than the material prepared with KOH.