scholarly journals Fabrication of Hybrid Catalyst ZnO Nanorod/α-Fe2O3 Composites for Hydrogen Evolution Reaction

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 356
Author(s):  
Kasimayan Uma ◽  
Elavarasan Muniranthinam ◽  
Siewhui Chong ◽  
Thomas C.-K Yang ◽  
Ja-Hon Lin
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Nickel Foam ◽  
Zno Nanorods ◽  
Synergetic Effect ◽  
Zno Nanorod ◽  
Fe2o3 Nanoparticles ◽  
X Ray

This report presents the synthesis of ZnO nanorod/α-Fe2O3 composites by the hydrothermal method with different weight percentages of α-Fe2O3 nanoparticles. The as-synthesized nanorod composites were characterized by different techniques, such as X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). From our results, it was found that the ZnO/α-Fe2O3 (3 wt%) nanorod composites exhibit a higher hydrogen evolution reaction (HER) activity when compared to other composites. The synergetic effect between ZnO and (3 wt%) of α-Fe2O3 nanocomposites resulted in a low onset potential of −125 mV, which can effectively produce more H2 than pure ZnO. The H2 production rate over the composite of ZnO/α-Fe2O3 (3 wt%) clearly shows a significant improvement in the photocatalytic activity in the heterojunction of the ZnO nanorods and α-Fe2O3 nanoparticles on nickel foam.

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.

Hydrothermal Synthesis of Few-Layer and Edge-Rich Cobalt-Doped Molybdenum Selenide/Nitrogenated Graphene Composite and Investigation of Its Electrocatalytic Activity for Hydrogen Evolution Reaction

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650107 ◽  
Author(s):  
Ming Ou ◽  
Lin Ma ◽  
Limei Xu ◽  
Zhuomei Yang ◽  
Haizhen Li
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Hydrothermal Route ◽  
X Ray ◽  
Graphene Composite ◽  
Molybdenum Selenide ◽  
Nitrogen Doped Graphene ◽  
Doped Graphene

Cobalt-doped MoSe2/nitrogenated graphene composite has been successfully synthesized via a facile hydrothermal route and is investigated as an electrocatalyst for hydrogen evolution reaction (HER). The as-prepared samples are well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Raman spectrum. The results reveal that Co-doped MoSe2 nanosheets which are characteristic of few layers (2–4 layers) and abundant exposed active edge sites are well anchored on the nitrogen-doped graphene sheets to constitute robust composites. When evaluated as catalysts for HER, the obtained composites demonstrate superior electrocatalytic activities toward HER.

scholarly journals Electrodeposition and characterization of Ni-MoO2 composite coatings as cathodes for the hydrogen evolution reaction in alkaline solution

2013 ◽  
Vol 78 (4) ◽  
pp. 549-554 ◽  
Author(s):  
Uros Lacnjevac
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Alkaline Solution ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Theoretical Interpretation ◽  
X Ray ◽  
Polarization Measurements ◽  
Naoh Solution

Composite Ni-MoO2 coatings were prepared and characterized with respect to their possible application as electrocatalysts for the hydrogen evolution reaction (HER) in alkaline solution. The composites were electrodeposited onto Ni meshes from an ammonium chloride Ni solution with suspended MoO2 particles in simulated industrial conditions for production of commercial cathodes. The influence of the concentration of MoO2 particles in the solution and deposition current density on the morphology, chemical and phase composition of obtained coatings was investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Catalytic activity for the HER of the coatings was examined by polarization measurements in a 32 wt. % NaOH solution at 90?C and compared to the activity of the commercial De Nora?s cathode (DN). It was shown that the most active Ni-MoO2 coating exhibits better polarization characteristics for the HER than the DN cathode. The mechanism of the HER on the specified Ni-MoO2 coating was investigated in 8 mol dm-3 NaOH at 30?C by means of steady-state polarization measurements and an electrochemical impedance spectroscopy (EIS) method. Based on the theoretical interpretation of the experimental data, rate constants of the three individual steps of the HER were determined and the source of catalytic activity of the coating was elucidated.

scholarly journals MoSe2-GO/rGO Composite Catalyst for Hydrogen Evolution Reaction

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1309 ◽  
Author(s):  
Wenwu Guo ◽  
Quyet Le ◽  
Amirhossein Hasani ◽  
Tae Lee ◽  
Ho Jang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Transition Metal Dichalcogenides ◽  
Catalytic Performance ◽  
Composite Catalyst ◽  
X Ray ◽  
Molybdenum Selenide

There has been considerable research to engineer composites of transition metal dichalcogenides with other materials to improve their catalytic performance. In this work, we present a modified solution-processed method for the formation of molybdenum selenide (MoSe2) nanosheets and a facile method of structuring composites with graphene oxide (GO) or reduced graphene oxide (rGO) at different ratios to prevent aggregation of the MoSe2 nanosheets and hence improve their electrocatalytic hydrogen evolution reaction performance. The prepared GO, rGO, and MoSe2 nanosheets were characterized by X-ray powder diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The electrocatalytic performance results showed that the pure MoSe2 nanosheets exhibited a somewhat high Tafel slope of 80 mV/dec, whereas the MoSe2-GO and MoSe2-rGO composites showed lower Tafel slopes of 57 and 67 mV/dec at ratios of 6:4 and 4:6, respectively. We attribute the improved catalytic effects to the better contact and faster carrier transfer between the edge of MoSe2 and the electrode due to the addition of GO or rGO.

scholarly journals Influence of Transition Metal on the Hydrogen Evolution Reaction over Nano-Molybdenum-Carbide Catalyst

Catalysts ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 294 ◽  
Author(s):  
Meng Chen ◽  
Yufei Ma ◽  
Yanqiang Zhou ◽  
Changqing Liu ◽  
Yanlin Qin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Molybdenum Carbide ◽  
Low Cost ◽  
X Ray ◽  
Energy And Environment ◽  
Molybdenum Carbides ◽  
Metal Doped

The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising way to solve energy and environment problems. In this work, various transition metals (Fe, Co, Ni, Cu, Ag, and Pt) were selected to support on molybdenum carbides by a simple organic-inorganic precursor carburization process. X-ray diffraction (XRD) analysis results indicated that the β-Mo2C phase was formed in all metal-doped samples. X-ray photoelectron spectroscopy analysis indicated that the binding energy of Mo2+ species (Mo2C) shifted to a lower value after metal was doped on the molybdenum carbide surface. Comparing with pure β-Mo2C, the electrocatalytic activity for HER was improved by transition metal doping on the surface. Remarkably, the catalytic activity improvement was more obvious when Pt was doped on molybdenum carbide (2% Pt-Mo2C). The 2% Pt-Mo2C required a η10 of 79 mV, and outperformed that of pure β-Mo2C (η10 = 410 mV) and other transition metal doped molybdenum carbides, with a small Tafel slope (55 mV/dec) and a low onset overpotential (32 mV) in 0.5 M H2SO4. Also, the 2% Pt-Mo2C catalyst demonstrated a high stability for the HER in 0.5 M H2SO4. This work highlights a feasible strategy to explore efficient electrocatalysts with low cost via engineering on the composition and nanostructure.

Two-Dimensional WS2/g-C3N4 Layered Heterostructures With Enhanced Pseudocapacitive and Electrocatalytic Properties

2020 ◽  
Author(s):  
Oluwafunmilola Ola ◽  
Yanqiu Zhu
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Carbon Nitride ◽  
Graphitic Carbon ◽  
Hybrid Nanocomposites ◽  
Graphitic Carbon Nitride ◽  
Electrochemical Performances ◽  
X Ray

Abstract In this work, tungsten-based hybrid nanocomposites were grown on interconnected, macroscopic graphitic carbon nitride scaffold after solvothermal treatment followed by sulfidation to attain multifunctional composite electrocatalysts. The physicochemical properties of the obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The tungsten-based composites were tested as electrodes for pseudocapacitors and as electrocatalysts for hydrogen evolution reaction, to take advantage of their porous graphitic carbon nitride features which would be beneficial for optimal ion transport to tungsten-based nanoparticles. These unique physicochemical features endow these composites with excellent electrochemical performances to reach a current density of 10 mA/cm2 for the hydrogen evolution reaction. In addition to demonstrating excellent specific capacitance, these hybrid nanocomposites also possess good stability after 8 hours of testing.

Synthesis and Sensing Properties of N-doped ZnO Nanorod Arrays on Quartz

2010 ◽  
Vol 1253 ◽  
Author(s):  
Boqian Yang ◽  
Xiaoyan Peng ◽  
Hongxin Zhang ◽  
Peterxian Feng ◽  
Marc Achermann
Keyword(s):  
Photoelectron Spectroscopy ◽  
Zno Nanorods ◽  
Zno Nanorod ◽  
Nanorod Arrays ◽  
Zno Nanorod Arrays ◽  
X Ray ◽  
Doped Zno ◽  
High Concentrations ◽  
Diffraction Patterns ◽  
Raman Scattering Spectra

AbstractUsing different pressures of nitrogen, N-doped ZnO nanorod arrays of various densities have been synthesized on quartz substrates by pulsed laser deposition techniques. The nanorods grow preferentially perpendicular to the quartz surface. X-ray diffraction patterns revealed some degradation of the crystal structure at elevated nitrogen pressures. High concentrations of nitrogen doping in ZnO nanorods were estimated by X-ray photoelectron spectroscopy. Raman scattering spectra confirmed the wurtzite structure of N-doped ZnO nanorods. A prototype sensor based on the N-doped ZnO nanorod arrays demonstrates a linear dependence of the conductivity with operating temperature and pressure of a test gas pollutant.

scholarly journals Synthesis and characterization of Ni2C: An efficient electrocatalyst towards hydrogen evolution reaction

2021 ◽  
Author(s):  
Sathish Vilvanathan ◽  
Roshini Gunasekaran
Keyword(s):  
Cyclic Voltammetry ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tafel Polarization ◽  
Nickel Carbide ◽  
One Step ◽  
Ft Ir

Abstract Ni2C electrocatalyst were synthesized and characterized for the Hydrogen Evolution Reaction (HER) electrolyzer. One step hydrothermal technique is used to synthesize Ni2C sample. Platinum based electro catalyst materials are initial and best electro catalyst for Hydrogen Evolution Reaction (HER). Ni2C (Nickel Carbide electro catalyst) was examined by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD). Electrochemical characterization like cyclic voltammetry (CV), Tafel polarization and electrochemical impedance spectroscopy (EIS) studies is employed to explore the elctrocatalytic behavior of Ni2C material for HER. FTIR study confirms the presence of Ni2C electrocatalyst by the presence of metal peaks and various functional groups. The isomeric nature and purity of synthesized material were explored by powder X-ray diffraction studies. Cyclic voltammetry technique was performed in 0.5 M H2SO4 solution to attain the polarization curve of Ni2C electrocatalyst for HER.

scholarly journals The Characterisation of Electrodeposited MoS2 Thin Films on a Foam-Based Electrode for Hydrogen Evolution

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1182
Author(s):  
Ramunas Levinas ◽  
Natalia Tsyntsaru ◽  
Henrikas Cesiulis
Keyword(s):  
Hydrogen Evolution ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Hydrogen Adsorption ◽  
Electrochemical Impedance ◽  
Electrical Circuit ◽  
Intrinsic Activity ◽  
Sodium Hypophosphite ◽  
X Ray ◽  
Circuit Components

Molybdenum sulphide is an emerging precious-metal-free catalyst for cathodic water splitting. As its active sites catalyse the Volmer hydrogen adsorption step, it is particularly active in acidic media. This study focused on the electrochemical deposition of MoS2 on copper foam electrodes and the characterisation of their electrocatalytic properties. In addition, the electrodeposition was modified by adding a reducing agent—sodium hypophosphite—to the electrolyte. To reveal the role of hypophosphite, X-ray photoelectron spectroscopy (XPS) analysis was carried out in addition to scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). MoS2 films, electrodeposited at various charges passed through the cell (catalyst loadings), were tested for their catalytic activity towards hydrogen evolution in 0.5 M H2SO4. Polarisation curves and Tafel slope analysis revealed that the electrodeposited MoS2 films are highly active. Namely, Tafel slopes fell within the 40–50 mV dec−1 range. The behaviour of as-deposited films was also evaluated by electrochemical impedance spectroscopy over a wide overpotential range (0 to −0.3 V), and two clear time constants were distinguished. Through equivalent electrical circuit analysis, the experimental data were fitted to the appropriate model, and the obtained values of the circuit components were examined as a function of overpotential. It was found that the addition of NaH2PO2 into the electrodeposition solution affects the intrinsic activity of the material. Finally, a method is proposed to approximate the number of active sites from impedance data.

Sign in / Sign up

Export Citation Format

Share Document