scholarly journals Enhanced hydrogen evolution reaction on hybrids of cobalt phosphide and molybdenum phosphide

2017 ◽  
Vol 4 (3) ◽  
pp. 161016 ◽  
Author(s):  
Si-Ling Fang ◽  
Tsu-Chin Chou ◽  
Satyanarayana Samireddi ◽  
Kuei-Hsien Chen ◽  
Li-Chyong Chen ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Electrolysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cobalt Phosphide ◽  
Production Of Hydrogen ◽  
Molybdenum Phosphide ◽  
Diffraction Patterns

Production of hydrogen from water electrolysis has stimulated the search of sustainable electrocatalysts as possible alternatives. Recently, cobalt phosphide (CoP) and molybdenum phosphide (MoP) received great attention owing to their superior catalytic activity and stability towards the hydrogen evolution reaction (HER) which rivals platinum catalysts. In this study, we synthesize and study a series of catalysts based on hybrids of CoP and MoP with different Co/Mo ratio. The HER activity shows a volcano shape and reaches a maximum for Co/Mo = 1. Tafel analysis indicates a change in the dominating step of Volmer–Hyrovský mechanism. Interestingly, X-ray diffraction patterns confirmed a major ternary interstitial hexagonal CoMoP 2 crystal phase is formed which enhances the electrochemical activity.

scholarly journals A Mini Review on Doped Nickel-Based Electrocatalysts for Hydrogen Evolution Reaction

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4651
Author(s):  
Yilin Deng ◽  
Wei Lai ◽  
Bin Xu
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Electrolysis ◽  
Energy Resources ◽  
Alkaline Media ◽  
Hydrogen Energy ◽  
Heteroatom Doping ◽  
Highly Active ◽  
Production Of Hydrogen

The energy crisis and environmental pollution have attracted much attention and have promoted researches on clean and sustainable hydrogen energy resources. With the help of highly active and stable transition metal nickel-based catalysts, the production of hydrogen from water electrolysis from electrolyzed water has become an inexpensive and efficient strategy for generating hydrogen energy. In recent years, heteroatom doping has been found to be an effective strategy to improve the electrocatalytic hydrogen evolution reaction (HER) performances of nickel-based catalysts in acidic, neutral, and alkaline media. This review will highlight many recent works of inexpensive and readily available heteroatom-doped nickel-based HER catalysts. The evaluation methods for the performances of HER catalyst will be briefly described, and the role of heteroatom doping and its application in nickel-based catalyst will be summarized. This article will also point out some heteroatom doping strategies, which may provide references and inspire the design of other catalysts with dopants.

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.

X-ray powder diffraction analysis of the heteropoly-molybdate (MoO2)0.5PMo14O42

2003 ◽  
Vol 18 (3) ◽  
pp. 236-239 ◽  
Author(s):  
L. Marosi ◽  
J. Cifré ◽  
C. Otero Areán
Keyword(s):  
Catalytic Activity ◽  
Diffraction Analysis ◽  
Computer Modeling ◽  
Powder Diffraction ◽  
Rietveld Analysis ◽  
Nitrogen Atmosphere ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

The new heteropoly blue compound (MoO2)0.5PMo14O42, which is relevant in the context of catalytic activity of heteropoly-molybdates, was prepared by controlled thermolysis of (NH4)3PMo12O40 at 730 K in a nitrogen atmosphere. Powder X-ray diffraction analysis showed that this compound has a cubic unit cell, space group Pn3m (No. 224), with ao=11.795(2) Å, Z=2 and DXR=4.2466 g cm−3. Computer modeling and Rietveld analysis of powder diffraction patterns led to a proposed structure of the corresponding Keggin-cage unit PMo14O42.

scholarly journals Ag/AgCl/MIL-101(Fe) Catalyzed Degradation of Methylene Blue under Visible Light Irradation

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1453 ◽  
Author(s):  
Yun Liu ◽  
Yuanhong Xie ◽  
Mingjin Dai ◽  
Qingjiao Gong ◽  
Zhi Dang
Keyword(s):  
Methylene Blue ◽  
Catalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Box Behnken Design ◽  
X Ray ◽  
Plasmonic Material ◽  
Fenton Catalyst ◽  
Diffraction Patterns

A novel photo-Fenton catalyst named Ag/AgCl/MIL-101(Fe) was synthesized by the method of precipitation and photo reduction and characterized by X-ray diffraction patterns (XRD), Brunauer-Emmett-Teller (BET) measurements, Fourier transform infrared spectra (FTIR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra. Moreover, the catalytic activity of the synthesized catalyst was tested using methylene blue (MB) as the target pollutant. The obtained results illustrated that the plasmonic material Ag/AgCl was successfully loaded on MIL-101(Fe) and the obtained catalyst exhibited an excellent catalytic activity under visible light at the neutral pH. According to the analyses of Plackett-Burman and Box-Behnken design, the optimum conditions for MB degradation were obtained. Under these conditions, the MB decolorization and mineralization efficiencies could reach to 99.75% and 65.43%, respectively. The recycling experiments also showed that the as-prepared catalyst displayed good reusability. In addition, the possible reaction mechanisms for the heterogeneous photo-Fenton system catalyzed by Ag/AgCl/MIL-101(Fe) were derived. The synthesized catalyst provides a promising approach to degrade organic pollutants in waste water.

Powder diffraction analysis of an interstratified marcasite/pyrite structure

1995 ◽  
Vol 10 (3) ◽  
pp. 198-203 ◽  
Author(s):  
Neil E. Johnson ◽  
Sidney S. Pollack ◽  
Elizabeth A. Frommell ◽  
Patricia A. Eldredge
Keyword(s):  
Catalytic Activity ◽  
Stacking Faults ◽  
Catalyst Precursor ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Naturally Occurring ◽  
Benzylic Carbon ◽  
Diffraction Peaks ◽  
Diffraction Patterns

A synthetic catalyst precursor formed by sulfiding ferrihydrite (Fe3+O(OH)) in the presence of a hydrogen donor produces X-ray diffraction patterns resembling a mixture of both naturally occurring FeS2 polymorphs marcasite and pyrite. The diffraction peaks display a differential broadening, however, wherein only those peaks coincident to both marcasite and pyrite are strong and sharp, a feature that cannot be accounted for by a simple physical mixture. The broadening is analogous to that found in hexagonal cobalt, where occasional stacking faults produce interstratification of the hexagonal and cubic close-packed forms, resulting in strongly coherent diffraction only along the stacking direction. The crystal structures of marcasite and pyrite are virtually identical if viewed perpendicular to the (101) and (001) planes, respectively. Calculation of diffraction patterns based upon models of interstratifying marcasite and pyrite layers along these planes demonstrates that a sequence with marcasite-to-pyrite and pyrite-to-marcasite stacking fault probabilities of 0.22 provides a good fit to the experimental pattern. This interstratified material is a precursor to a species that shows catalytic activity for cleaving C-C bonds between aromatic rings and benzylic carbon atoms at low (<350 °C) temperatures.

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 Single-Atom Catalysts for Electrochemical Hydrogen Evolution Reaction: Recent Advances and Future Perspectives

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Zonghua Pu ◽  
Ibrahim Saana Amiinu ◽  
Ruilin Cheng ◽  
Pengyan Wang ◽  
Chengtian Zhang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Water Electrolysis ◽  
Utilization Efficiency ◽  
Single Atom ◽  
Synthesis Methods ◽  
Electrochemical Characteristics ◽  
Scale Production ◽  
Substantial Impact ◽  
Production Of Hydrogen

AbstractHydrogen, a renewable and outstanding energy carrier with zero carbon dioxide emission, is regarded as the best alternative to fossil fuels. The most preferred route to large-scale production of hydrogen is by water electrolysis from the intermittent sources (e.g., wind, solar, hydro, and tidal energy). However, the efficiency of water electrolysis is very much dependent on the activity of electrocatalysts. Thus, designing high-effective, stable, and cheap materials for hydrogen evolution reaction (HER) could have a substantial impact on renewable energy technologies. Recently, single-atom catalysts (SACs) have emerged as a new frontier in catalysis science, because SACs have maximum atom-utilization efficiency and excellent catalytic reaction activity. Various synthesis methods and analytical techniques have been adopted to prepare and characterize these SACs. In this review, we discuss recent progress on SACs synthesis, characterization methods, and their catalytic applications. Particularly, we highlight their unique electrochemical characteristics toward HER. Finally, the current key challenges in SACs for HER are pointed out and some potential directions are proposed as well.

scholarly journals Elucidating the formation and structural evolution of platinum single-site catalysts for hydrogen evolution reaction

2021 ◽  
Author(s):  
Peng Tang ◽  
Hyeon Jeong Lee ◽  
Kevin Hurlbutt ◽  
Po-Yuan Huang ◽  
Sudarshan Narayanan ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Clean Energy ◽  
Single Site ◽  
Ex Situ ◽  
Edge Structure ◽  
X Ray ◽  
Production Of Hydrogen ◽  
Single Site Catalysts ◽  
X Ray Absorption

Platinum single-site catalysts (SSCs) are a promising technology for the production of hydrogen from clean energy sources. They have high activity and maximal platinum-atom utilisation. However, the bonding environment of platinum during operation is poorly understood. In this work, we use operando, synchrotron-X-ray absorption spectroscopy to study the platinum bonding in SSCs. First, we synthesise an atomically dispersed platinum complex with aniline and chloride ligands onto graphene and characterise it with ex-situ electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), and extended X-ray absorption fine structure spectroscopy (EXAFS). Then, by operando EXAFS and XANES, we show that as a negatively biased potential is applied, the Pt-N bonds break first followed by the Pt-Cl bonds. The platinum is reduced from platinum(II) to metallic platinum(0) by the onset of the hydrogen-evolution reaction at 0 V. Furthermore, we observe an increase in Pt-Pt bonding, indicating the formation of platinum agglomerates. Together, these results indicate that while aniline is used to prepare platinum SSCs, the single-site complexes are decomposed and platinum agglomerates at operating potentials. This work is an important contribution to the understanding of the bonding environment and the evolution of the molecular structure of platinum complexes in SSCs.

scholarly journals MoS2-Carbon Inter-overlapped Structures as Effective Electrocatalysts for the Hydrogen Evolution Reaction

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1389
Author(s):  
Po-Chia Huang ◽  
Chia-Ling Wu ◽  
Sanjaya Brahma ◽  
Muhammad Omar Shaikh ◽  
Jow-Lay Huang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Hydrogen Generation ◽  
Interlayer Spacing ◽  
Monolayer Mos2 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

The ability to generate hydrogen in an economic and sustainable manner is critical to the realization of a future hydrogen economy. Electrocatalytic water splitting into molecular hydrogen using the hydrogen evolution reaction (HER) provides a viable option for hydrogen generation. Consequently, advanced non-precious metal based electrocatalysts that promote HER and reduce the overpotential are being widely researched. Here, we report on the development of MoS2-carbon inter-overlapped structures and their applicability for enhancing electrocatalytic HER. These structures were synthesized by a facile hot-injection method using ammonium tetrathiomolybdate ((NH4)2MoS4) as the precursor and oleylamine (OLA) as the solvent, followed by a carbonization step. During the synthesis protocol, OLA not only plays the role of a reacting solvent but also acts as an intercalating agent which enlarges the interlayer spacing of MoS2 to form OLA-protected monolayer MoS2. After the carbonization step, the crystallinity improves substantially, and OLA can be completely converted into carbon, thus forming an inter-overlapped superstructure, as characterized in detail using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). A Tafel slope of 118 mV/dec is obtained for the monolayer MoS2-carbon superstructure, which shows a significant improvement, as compared to the 202 mV/dec observed for OLA-protected monolayer MoS2. The enhanced HER performance is attributed to the improved conductivity along the c-axis due to the presence of carbon and the abundance of active sites due to the interlayer expansion of the monolayer MoS2 by OLA.

Sign in / Sign up

Export Citation Format

Share Document