Pt Nanoparticles Decorated on Fe2O3/N, P-Doped Mesoporous Carbon for Enhanced Oxygen Reduction Activity and Durability

2020 ◽  
Vol 18 (2) ◽  
Author(s):  
Sabarinathan Ravichandran ◽  
Narayanamoorthy Bhuvanendran ◽  
Kai Peng ◽  
Weiqi Zhang ◽  
Qian Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Alkaline Media ◽  
Active Surface Area ◽  
X Ray

Abstract The Pt–Fe2O3 nanoparticles embedded over N, P-doped carbon (Pt–Fe2O3/NPC) was successfully synthesized by chemical reduction method demonstrating an enhanced electrocatalytic efficacy in alkaline media toward oxygen reduction reaction (ORR). The surface morphology of Pt–Fe2O3/NPC has been characterized by electron microscopy scanning, X-ray diffraction, electron microscopy transmission, Raman spectra, and X-ray photoelectron spectroscopy. The ORR electrocatalytic activity of Pt–Fe2O3/NPC was found to be the superior mass activity of 0.120 mA µg−1, which are almost twice higher than those for Pt–Fe2O3/VC (0.068 mA µg−1) and Pt/C (0.061 mA µg−1) catalysts. The durability tests revealed that the Pt–Fe2O3/NPC exhibited enhanced stability observed from the order of electrochemical active surface area (ECA) loss determined as Pt–Fe2O3/NPC (45.67%) <Pt–Fe2O3/VC (62.5%) <(Pt/C (72.13%) after 5000 cycles. This present investigation unveiled a facile approach to develop the number of active sites with the combination between P–Fe2O3 and N, P-doped carbon for improved electrocatalytic performance toward ORR.

scholarly journals Synergistic Effects of Active Sites’ Nature and Hydrophilicity on the Oxygen Reduction Reaction Activity of Pt-Free Catalysts

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 643 ◽  
Author(s):  
Mariangela Longhi ◽  
Camilla Cova ◽  
Eleonora Pargoletti ◽  
Mauro Coduri ◽  
Saveria Santangelo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Carbon Nanostructures ◽  
Active Sites ◽  
Active Material ◽  
Reduction Reaction ◽  
X Ray

This work highlights the importance of the hydrophilicity of a catalyst’s active sites on an oxygen reduction reaction (ORR) through an electrochemical and physico-chemical study on catalysts based on nitrogen-modified carbon doped with different metals (Fe, Cu, and a mixture of them). BET, X-ray Powder Diffraction (XRPD), micro-Raman, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and hydrophilicity measurements were performed. All synthesized catalysts are characterized not only by a porous structure, with the porosity distribution centered in the mesoporosity range, but also by the presence of carbon nanostructures. In iron-doped materials, these nanostructures are bamboo-like structures typical of nitrogen carbon nanotubes, which are better organized, in a larger amount, and longer than those in the copper-doped material. Electrochemical ORR results highlight that the presence of iron and nitrogen carbon nanotubes is beneficial to the electroactivity of these materials, but also that the hydrophilicity of the active site is an important parameter affecting electrocatalytic properties. The most active material contains a mixture of Fe and Cu.

Effect of Reducing Agent on the Dispersion of Pt Nanoparticles on Electrospun Nb0.1Ti0.9O2 Nanofibers

2013 ◽  
Vol 1542 ◽  
Author(s):  
Esmaeil Navaei Alvar ◽  
Biao Zhou ◽  
S. Holger Eichhorn
Keyword(s):  
Electron Microscopy ◽  
Ethylene Glycol ◽  
Surface Area ◽  
Sodium Borohydride ◽  
Chemical Reduction ◽  
Pt Nanoparticles ◽  
Surfactant Solution ◽  
Pem Fuel Cells ◽  
Active Surface Area ◽  
X Ray

ABSTRACTDegradation of the catalyst and catalyst support is an essential limitation of polymer electrolyte membrane (PEM) fuel cells containing commercial platinum on carbon catalysts. Catalysts based on platinum nanoparticles coated onto nanostructured TiO2 materials are presently investigated as a more stable and equally cost effective alternative. Reported here is the synthesis of two different Pt/Nb0.1Ti0.9O2 catalysts that were prepared by chemical reduction of H2PtCl6 with either sodium borohydride in ethanolic surfactant solution or ethylene glycol. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy confirmed the deposition of Pt nanoparticles on the surface of the nanofibers and revealed average sizes of 5.4 nm and 7.6 nm for reduction with ethylene glycol and sodium borohydride, respectively. The formation of smaller sized Pt nanoparticles in ethylene glycol is reasoned with the passivation of the nanoparticle surface by glycolic anions. Cyclic voltammetry measurements confirmed a higher electrochemical specific surface area (ESCA) of about 5.45 m2/gPt for the catalyst with smaller nanoparticles while the other catalyst reached only 4.96m2/gPt. Both catalysts retain about 60% of their electrochemically active surface area after 1000 voltammetric cycles in the range of 0.03 to 1.4 V vs. RHE. This relatively high value of activity retention is explained with a strong interaction between Pt nanoparticles and Nb0.1Ti0.9O2 support.

Facile deposition of Pt nanoparticles on Sb-doped SnO2 support with outstanding active surface area for the oxygen reduction reaction

2018 ◽  
Vol 8 (10) ◽  
pp. 2672-2685 ◽  
Author(s):  
Rhiyaad Mohamed ◽  
Tobias Binninger ◽  
Patricia J. Kooyman ◽  
Armin Hoell ◽  
Emiliana Fabbri ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Pt Nanoparticles ◽  
Active Surface ◽  
Reduction Reaction ◽  
Active Surface Area

Synthesis of Sb–SnO2 supported Pt nanoparticles with an outstanding ECSA for the oxygen reduction reaction.

scholarly journals Amorphous Ni x Co y P-supported TiO2 nanotube arrays as an efficient hydrogen evolution reaction electrocatalyst in acidic solution

2019 ◽  
Vol 10 ◽  
pp. 62-70 ◽  
Author(s):  
Yong Li ◽  
Peng Yang ◽  
Bin Wang ◽  
Zhongqing Liu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Nanotube Arrays ◽  
Active Surface Area ◽  
X Ray ◽  
Transmission Electron

Bimetallic phosphides have been attracting increasing attention due to their synergistic effect for improving the hydrogen evolution reaction as compared to monometallic phosphides. In this work, NiCoP modified hybrid electrodes were fabricated by a one-step electrodeposition process with TiO2 nanotube arrays (TNAs) as a carrier. X-ray diffraction, transmission electron microscopy, UV–vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy and scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy were used to characterize the physiochemical properties of the samples. The electrochemical performance was investigated by cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. We show that after incorporating Co into Ni–P, the resulting Ni x Co y P/TNAs present enhanced electrocatalytic activity due to the improved electron transfer and increased electrochemically active surface area (ECSA). In 0.5 mol L−1 H2SO4 electrolyte, the Ni x Co y P/TNAs (x = 3.84, y = 0.78) demonstrated an ECSA value of 52.1 mF cm−2, which is 3.8 times that of Ni–P/TNAs (13.7 mF cm−2). In a two-electrode system with a Pt sheet as the anode, the Ni x Co y P/TNAs presented a bath voltage of 1.92 V at 100 mA cm−2, which is an improvment of 79% over that of 1.07 V at 10 mA cm−2.

scholarly journals MOF-Derived CuPt/NC Electrocatalyst for Oxygen Reduction Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 799 ◽  
Author(s):  
Rehan Anwar ◽  
Naseem Iqbal ◽  
Saadia Hanif ◽  
Tayyaba Noor ◽  
Xuan Shi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Photoelectron Spectroscopy ◽  
Rotating Disk ◽  
Reduction Reaction ◽  
Rotating Disk Electrode ◽  
X Ray ◽  
Onset Potential ◽  
Orr Activity

Metal-organic frameworks (MOFs) have been at the center stage of material science in the recent past because of their structural properties and wide applications in catalysis. MOFs have also been used as hard templates for the preparation of catalysts. In this study, highly active CuPt/NC electrocatalyst was synthesized by pyrolyzing Cu-tpa MOF along with Pt precursor under flowing Ar-H2 atmosphere. The catalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD). Rotating disk electrode study was performed to determine the oxygen reduction reaction (ORR) activity for CuPt/NC in 0.1 M HClO4 at different revolutions per minute (400, 800, 1200, and 1600) and it was also compared with commercial Pt/C catalyst. Further the ORR performance was evaluated by K-L plots and Tafel slope. CuPt/NC shows excellent ORR performance with onset potential of 0.9 V (vs. RHE), which is comparable with commercial Pt/C. The ORR activity of CuPt/NC is demonstrated as an efficient electrocatalyst for fuel cell.

scholarly journals Metallic Organic Framework-Derived Fe, N, S co-doped Carbon as a Robust Catalyst for the Oxygen Reduction Reaction in Microbial Fuel Cells

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3846 ◽  
Author(s):  
Xiao Luo ◽  
Wuli Han ◽  
Han Ren ◽  
Qingzuo Zhuang
Keyword(s):  
Fuel Cells ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Microbial Fuel Cells ◽  
Active Sites ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
X Ray ◽  
Co Doped ◽  
Organic Framework

Oxygen reduction reaction (ORR) provides a vital role for microbial fuel cells (MFCs) due to its slow reaction kinetics compared with the anodic oxidation reaction. How to develop new materials with low cost, high efficacy, and eco-friendliness which could replace platinum-based electrocatalysis is a challenge that we have to resolve. In this work, we accomplished this successfully by means of a facile strategy to synthesize a metallic organic framework-derived Fe, N, S co-doped carbon with FeS as the main phase. The Fe/S@N/C-0.5 catalyst demonstrated outstandingly enhanced ORR activity in neutral PBS and alkaline media, compared to that of commercial 20% Pt-C catalyst. Here, we started-up and operated two parallel single-chamber microbial fuel cells of an air cathode, and those cathode catalysts were Fe/S@N/C-0.5 and commercial Pt-C (20% Pt), respectively. Scanning electron microscopy (SEM) elaborated that the Fe/S@N/C-0.5 composite did not change the polyhedron morphology of ZIF-8. According to X-ray diffractometry(XRD) curves, the main crystal phase of the resulted Fe/S@N/C-0.5 was FeS. The chemical environment of N, S, and Fe which are anticipated to be the high-efficiency active sites of ORR for MFCs were investigated by X-ray photoelectron spectroscopic(XPS). Nitrogen adsorption/desorption techniques were used to calculate the pore diameter distribution. In brief, the obtained Fe/S@N/C-0.5 material exhibited a pronounced reduction potential at 0.861 V (versus Reversible Hydrogen Electrode(RHE)) in 0.1M KOH solution and –0.03 V (vs. SCE) in the PBS solution, which both outperform the benchmark platinum-based catalysts. Fe/S@N/C-0.5-MFC had a higher Open Circuit Voltage(OCV) (0.71 V), stronger maximum power density (1196 mW/m2), and larger output voltage (0.47 V) than the Pt/C-MFC under the same conditions.

scholarly journals The Preparation and Catalytic Properties of Nanoporous Pt/CeO2 Composites with Nanorod Framework Structures

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 683 ◽  
Author(s):  
Haiyang Wang ◽  
Dong Duan ◽  
Chen Ma ◽  
Wenyu Shi ◽  
Miaomiao Liang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Catalytic Properties ◽  
Structural Parameters ◽  
Active Oxygen Species ◽  
Pt Nanoparticles ◽  
Strong Interactions ◽  
X Ray ◽  
Small Pore ◽  
Melt Spun

Pt/CeO2 catalysts with nanoporous structures were prepared by the facile dealloying of melt-spun Al92−XCe8PtX (X = 0.1; 0.3 and 0.5) ribbons followed by calcination. The phase compositions and structural parameters of the catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The specific surface area and pore size distribution were characterized by N2 adsorption–desorption tests. The catalytic properties were evaluated by a three-way catalyst (TWC) measurement system. The results revealed that the dealloyed samples exhibited a nanorod framework structure. The Pt nanoparticles that formed in situ were supported and highly dispersed on the CeO2 nanorod surface and had sizes in the range of 2–5 nm. For the catalyst prepared from the melt-spun Al91.7Ce8Pt0.3 ribbons, the 50% CO conversion temperature (T50) was 91 °C, and total CO could be converted when the temperature was increased to 113 °C. An X-ray photoelectron spectroscopy (XPS) test showed that the Pt0.3/CeO2 sample had a slightly richer oxygen vacancy; and a H2 temperature-programmed reduction (H2-TPR) test demonstrated its superior adsorption ability for reduction gas and high content of active oxygen species. The experiments indicated that the catalytic performance could be retained without any attenuation after 130 h when water and CO2 were present in the reaction gas. The favorable catalytic activities were attributed to the high specific areas and small pore and Pt particle sizes as well as the strong interactions between the CeO2 and Pt nanoparticles. The Pt nanoparticles were embedded in the surface of the CeO2 nanorods, inhibiting growth. Therefore, the catalytic stability and water resistance were excellent.

Mesoporous Co–B amorphous alloy films with enhanced catalytic efficiency prepared from a mixed-surfactant solution

2009 ◽  
Vol 24 (11) ◽  
pp. 3300-3307 ◽  
Author(s):  
Hui Li ◽  
Jun Liu ◽  
Haixia Yang ◽  
Hexing Li
Keyword(s):  
Amorphous Alloy ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Reduction ◽  
Surfactant Solution ◽  
Mesoporous Structure ◽  
Mixed Surfactant ◽  
Alloy Films ◽  
X Ray ◽  
Electron Micrography

Co–B films were synthesized through the solvent evaporation-assisted chemical reduction method by using a mixed-surfactant solution containing Span 40 and (1S)-(+)-10-camphorsulfonic acid. With the characterization of x-ray diffraction, selected-area electron diffraction, x-ray photoelectron spectroscopy, scanning electron micrography, and transmission electron micrography, the resulting Co–B films were identified to be amorphous alloys with mesoporous structure. The synergistic effect of two kinds of surfactants is essential for the formation of mesoporous structure. During liquid-phase cinnamaldehyde hydrogenation to cinnamyl alcohol, the mesoporous Co–B amorphous alloy films exhibited a much higher activity and better selectivity than the solid Co–B nanoparticles prepared by direct reduction of cobalt ions with borohydride. The enhanced activity is attributed to both the mesoporous and the film structure, which provides more Co active sites for the adsorption and diffusion of reactant molecules. The improved selectivity may be related to the difference in surface curvature.

Co3O4 Nanoparticles-Modified α-MnO2 Nanorods Supported on Reduced Graphene Oxide as Cathode Catalyst for Oxygen Reduction Reaction in Alkaline Media

NANO ◽  
2016 ◽  
Vol 11 (11) ◽  
pp. 1650126 ◽  
Author(s):  
GuanHua Jin ◽  
Suqin Liu ◽  
Yaomin Li ◽  
Yang Guo ◽  
Zhiying Ding
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Catalytic Activity ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduced Graphene Oxide ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
X Ray ◽  
Reduced Graphene

Development of efficient electrocatalysts for the oxygen reduction reaction (ORR) remains a key issue for the commercialization of metal-air batteries. In this study, the novel structured Co3O4 nanoparticles-modified [Formula: see text]-MnO2 nanorods supported on reduced graphene oxide (Co3O4-MnO2/rGO) were synthesized with varying amounts of [Formula: see text]-MnO2 via a facile two-step hydrothermal method. The relationship between the physical properties and the electrochemical results was investigated using X-ray diffraction spectrum, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammograms, electrochemical impedance spectroscopy and rotating disk electrode. The as-prepared Co3O4–MnO2 nanohybrid exhibits enhanced catalytic activity for ORR under alkaline condition compared with MnO2/rGO and Co3O4/rGO. Furthermore, it mainly favors a direct 4e-reaction pathway for ORR, which is attributed to the well-designed structure, the synergistic effect between Co3O4 and [Formula: see text]-MnO2, and the covalent coupling between the Co3O4-MnO2 and reduced graphene oxide. The role of Co3O4 in Co3O4–MnO2 hybrid for catalyzing ORR also has been illustrated by varying the mass ratio of Co3O4 and MnO2, which reveals that the Co3O4–MnO2 with the ratio of 1:1 has better catalytic activity.

Electroless Synthesis of 1.4 nm Pd and Pt Nanoparticles on Self-Assembled Rosette Nanotubes

2011 ◽  
Vol 1301 ◽  
Author(s):  
Rahul Chhabra ◽  
Hicham Fenniri
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Pt Nanoparticles ◽  
Hierarchical Organization ◽  
X Ray ◽  
Force Microscopy ◽  
Rosette Nanotubes ◽  
Atomic Force ◽  
Transmission Electron ◽  
Self Assembled

ABSTRACTElectroless synthesis and hierarchical organization of 1.4 nm Pd and Pt nanoparticles (NPs) on self-assembled Rosette Nanotubes (RNTs) is described. The nucleated NPs are nearly monodisperse and reveal supramolecular organizations guided by RNT templates. Interestingly, the narrow size distribution is attributable to unique templating behavior of RNTs. The resulting metal NP-RNT composites were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). X-ray Photoelectron Spectroscopy (XPS) was also performed to confirm the nature and composition of RNT-templated NPs.

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