Electro deposition of platinum nanoparticles on reduced graphene oxide as an efficient catalyst for oxygen reduction reaction (original) (raw)
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Journal of Materials Chemistry, 2012
In this paper, we demonstrate two novel green synthesis methods for preparing platinum-graphene catalysts for proton exchange membrane fuel cell (PEMFC) applications. Starting from graphite oxide, the platinum precursor is added and the composite is separately subjected to (a) focused solar radiation and (b) hydrogen gas, for carrying out simultaneous reduction of graphite oxide to graphene and platinum complexes to platinum nanoparticles. These co-reduction methods employ a single agent, namely either sunlight or hydrogen gas, to accomplish the reduction process. Both techniques are therefore cost and energy effective and capable of large scale production. Rotating disc electrode (RDE) and PEMFC measurements reveal the high performance of these electrocatalysts as compared to commercial Pt-C electrocatalysts due to high oxygen reduction reaction (ORR) activity. Stability studies show that both catalysts are highly stable under acidic medium. The proposed methods are quite general in their applicability and we believe that these can be extended for synthesizing a wide variety of electrocatalysts such as various metal, metal oxide or metal alloy nanoparticle decorated carbon nanostructures.
International Journal of Hydrogen Energy, 2018
In this work, a comprehensive study on the polyol synthesis of platinum supported on reduced graphene oxide (Pt/rGO) catalysts, including both ex-situ and in-situ characterizations of the prepared Pt/rGO catalysts, was performed. The polyol synthesis was studied considering the influence of the platinum precursor, oxidation level of graphite oxide and pH of reaction medium. The as-prepared catalysts were analyzed using thermogravimetric (TG) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and cyclic voltammetry (CV). The best results in terms of platinum particle size and distribution were obtained when the synthesis was performed in acidic medium, using chloroplatinic acid as precursor and using graphene oxide with high oxidation level. The most promising graphene-supported catalyst was used to prepare a polymer electrolyte membrane fuel cell electrode. The membrane electrode assembly (MEA) prepared with graphene-based electrode was compared with a MEA prepared with catalyst based on commercial platinum supported in carbon black (Pt/C). Single cell characterization included polarization curves and in-situ electrochemical impedance spectroscopy (EIS). The graphene-based electrode presented promising albeit unstable electrochemical performance due to water management issues. Additionally, EIS measurements revealed that the MEA made with Pt/rGO catalyst presented a lower mass transport resistance than the commercial Pt/C.
Catalysts
Platinum (Pt)-based electrocatalysts supported by reduced graphene oxide (RGO) were synthesized using two different methods, namely: (i) a conventional two-step polyol process using RGO as the substrate, and (ii) a modified polyol process implicating the simultaneous reduction of a Pt nanoparticle precursor and graphene oxide (GO). The structure, morphology, and electrochemical performances of the obtained Pt/RGO catalysts were studied and compared with a reference Pt/carbon black Vulcan XC-72 (C) sample. It was shown that the Pt/RGO obtained by the optimized simultaneous reduction process had higher Pt utilization and electrochemically active surface area (EASA) values, and a better performance stability. The use of this catalyst at the cathode of a proton exchange membrane fuel cell (PEMFC) led to an increase in its maximum power density of up to 17%, and significantly enhanced its performance especially at high current densities. It is possible to conclude that the optimized synt...
ChemElectroChem, 2018
Platinum nanoparticles were deposited on reduced graphene oxide (rGO) and nitrogen-doped rGO (rGOÀN) by He/H 2 plasma jet treatment of H 2 PtCl 6 aqueous solution for electroreduction of oxygen. Physical characterization of the prepared catalysts was performed by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Electrochemical characterization was carried out by cyclic voltammetry and CO-stripping techniques. The oxygen reduction reaction (ORR) activity of the prepared Pt/rGO and Pt/ rGOÀN catalyst materials was investigated using the rotating disk electrode method in 0.1 M KOH and 0.05 M H 2 SO 4. In both acidic and alkaline electrolytes, the catalyst materials prepared by the plasma jet method demonstrated superior electrocatalytic properties compared to that of commercial 20 wt% Pt/ C catalyst. Specific activity values for the ORR in acid electrolyte were 2-fold and in alkaline media more than 3-fold higher than that obtained for commercial Pt/C catalyst.
Journal of Electroanalytical Chemistry, 1993
Here we demonstrate a remarkable enhancement of oxygen reduction reaction (ORR) activity on a novel Pt/ TaO x /GC electrocatalyst where at first tantalum oxide (TaO x ) and next Pt were deposited electrochemically on a glassy carbon (GC) surface. An excellent electrocatalytic activity of the Pt/TaO x / GC electrocatalyst for ORR was found to be more than 12 times that of the unmodified Pt/GC one as evaluated from the kinetic currents at 0.80 V. SEM images showed no significant differences in the size and distribution of Pt nanoparticles between these two electrocatalysts, indicating that these are not factors causing the observed ORR activity. The spillover of oxygen-containing species resulting from the electronic interaction between Pt and TaO x , which is evidently demonstrated from the XPS analysis, is strongly suggested as the crucial factor for the ORR enhancement. Interestingly, the spillover effect also results in a remarkable increase in the electrochemically active "apparent" surface area of Pt on the Pt/TaO x /GC electrocatalyst. Moreover, the rotating ring-disk electrode voltammetric measurements obviously showed the increase in limiting current as well as the decrease in ring current on this novel electrocatalyst relative to the unmodified one, confirming a complete four-electron reduction pathway. On the basis of these findings a plausible mechanism has been proposed for the observed enhancement in ORR where the role of TaO x is to reduce the formation of OH on the Pt surface by spillover effect and to promote d orbital vacancy of Pt for oxygen adsorption by electron donation to Ta.
Journal of Power Sources, 2005
Platinum on carbon is the most popular electrocatalyst for oxygen reduction in acid fuel cells. In this study electrocatalysts based on six types of carbon substrate are prepared according to American Society for Testing and Materials (ASTM) standards. The electrocatalysts are made either by a direct method, in which sodium formate is used as a reducing agent, or by an indirect method, in which PtO 2 /C is treated under four different conditions. A platinum loading of 0.5 mg cm −2 is used in all cases. The effects of the type of carbon support and the method of preparation of the electrocatalyst are investigated by electrochemical techniques, X-ray diffraction, scanning electron microscopy and N 2 adsorption. The combination of substrate type and preparation procedure that gives electrodes with the best performance is direct reduction using sodium formate as a reductant and sample N339 as a carbon substrate. For this optimum electrocatalyst, the symmetry factor and exchange current density are 0.5279 and 95.6 mA cm −2 in the rate-determining step, respectively.
Energy, 2014
Effects of the reduction temperature and the pH value of Pt precursor solutions of the polyol reduction process on the resulted Pt electrocatalysts supported on the reduced graphene oxide (Pt/r-GO) nanosheets for the ORR (oxygen reduction reaction) are investigated. The Pt/r-GO catalyst possesses Pt nanoparticles having an average size from 2 to 4 nm and a Pt loading from 13 to 20 wt%. The electrochemical performance of the Pt/r-GO catalysts is examined with the glassy carbon RDE (rotating disk electrode) technique in the O 2-saturated HClO 4 (0.5 M) solution. The Pt/r-GO catalysts have less ORR limiting currents near 3.5 mA cm À2 , but, in general, the more positive onset potentials than the commercial Pt/carbon black catalysts. The number of electron transfer in ORR over the Pt/r-GO catalysts is 3.85 in average, close to that of a 4-electron transfer process.
Carbon, 2016
A fuel cell is an electrochemical cell that converts a source fuel into an electrical current. It generates electricity inside a cell through reactions between a fuel and an oxidant, triggered in the presence of an electrolyte. Fuel cells have been attracting more and more attention in recent decades due to high-energy demands, fossil fuel depletions and environmental pollution throughout world. In this study, a facile and costeffective catalysts have been developed on platinum nanoparticles (PtNPs) supported on nitrogen and sulfurdoped reduced graphene oxide (NSrGO). The successful synthesis of nanomaterials and the prepared glassy carbon electrode (GCE) surfaces were confirmed by transmission electron microscope (TEM), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS). According to TEM images, the average particle sizes of PtNPs were found to be approximately 15-20 nm. The effective surface areas (ESA) of NSrGO/ GCE and PtNPs/NSrGO/GCE were calculated to be 148 and 469 cm 2 /mg, respectively. The PtNPs/NSrGO/GCE also exhibited a higher peak current for methanol oxidation than those of comparable GCE and NSrGO/GCE, providing evidence for its higher electro-catalytic activity.
Catalysts
Oxygen reduction reaction (ORR) is a very important reaction that occurs at the cathodic side in proton exchange membrane fuel cells (PEMFCs). The high cost associated with frequently used Pt-based electrocatalysts for ORR limits the commercialization of PEMFCs. Through bifunctional and electronic effects, theoretical calculations have proved that alloying Pt with a suitable transition metal is likely to improve ORR mass activity when compared to Pt-alone systems. Herein, we demonstrate the preparation of bimetallic Pt–Fe nanoparticles supported on reduced graphene oxide sheets (RGOs) via a simple surfactant-free chemical reduction method. The present method produces PtFe/RGO catalyst particles with a 3.2 nm diameter without agglomeration. PtFe/RGO showed a noticeable positive half-wave potential (0.503 V vs. Ag/AgCl) compared with a commercial Pt/C catalyst (0.352 V vs. Ag/AgCl) with minimal Pt-loading on a glassy carbon electrode. Further, PtFe/RGO showed a higher ORR mass activit...