Boosting pH-Universal Hydrogen Evolution of FeP/CC by Anchoring Trace Platinum

To improve the electrocatalytic properties for hydrogen evolution reactions, strategies need to be adopted, such as increasing specific surface area and active site, as well as decreasing interface energy. Herein, we report the preparation of FeP on carbon cloth using a two-step process of hydrothermal and phosphating. Otherwise, to utilize the excellent catalytic performance of Pt and decrease consumption of Pt, the hyperdispersed Pt nanoparticles for the sake of modifying transition-metal phosphides film were designed and fabricated. Finally, 3D FeP-Pt/CC was successfully prepared by means of electro-deposition using three electrodes. The crystalline structure, surface morphology and elemental composition of the synthesized samples have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS). The XRD results show that the as-prepared products are of orthorhombic FeP structure, and EDS results indicate that there exist Pt elements in 3D FeP-Pt/CC. The electrocatalytic performances were evaluated by, such as linear scan voltammetry, tafel plots and electrochemical impedance spectroscopy on electrochemical workstations. These results show that the FeP-Pt/CC exhibit a current density of 10 mA·cm−2 at an over-potential of 58 mV for HER in 0.5 M H2SO4, which is very close to the values of 20%Pt/C which was previously reported. FeP-Pt/CC has excellent durability.

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

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.10.6 ◽

2019 ◽

Vol 10 ◽

pp. 62-70 ◽

Cited By ~ 5

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.

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

Crystals ◽

10.3390/cryst10050356 ◽

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.

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MoSe2-GO/rGO Composite Catalyst for Hydrogen Evolution Reaction

Polymers ◽

10.3390/polym10121309 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1309 ◽

Cited By ~ 15

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.

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Methanol Oxidation on Graphenic-Supported Platinum Catalysts

Surfaces ◽

10.3390/surfaces2010002 ◽

2019 ◽

Vol 2 (1) ◽

pp. 16-31 ◽

Cited By ~ 15

Author(s):

Gladys Arteaga ◽

Luis M. Rivera-Gavidia ◽

Sthephanie J. Martínez ◽

Rubén Rizo ◽

Elena Pastor ◽

...

Keyword(s):

Graphene Oxide ◽

Methanol Oxidation ◽

Photoelectron Spectroscopy ◽

Oxidation Reaction ◽

Catalyst Support ◽

Pt Nanoparticles ◽

Catalytic Performance ◽

Methanol Oxidation Reaction ◽

X Ray ◽

Supported Platinum Catalysts

Graphene oxide (GO), reduced graphene oxide by thermal treatment (rGO-TT), nitrogen-modified rGO (N-rGO), and carbon Vulcan were synthesized and employed in the current work as catalyst support for Pt nanoparticles, to study their properties and impact toward the methanol oxidation reaction (MOR) in sulfuric acid medium. Several physicochemical techniques, such as X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman, and elemental analysis were employed to characterize the novel materials, while potentiodynamic and potentiostatic methods were used to study catalytic performance toward the methanol oxidation reaction in acidic medium. The main results indicate a high influence of the support on the surface electronic state of the catalyst, and consequently the catalytic performance toward the MOR is modified. Accordingly, Pt/N-rGO and Pt/rGO-TT show the lowest and the highest catalytic performance toward the MOR, respectively.

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

Catalysts ◽

10.3390/catal10101182 ◽

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.

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Study of Pt Nanoparticles Protected by 1-Dodecanethiol Self-Assembled Films on Iron Surface Using Electrochemical Methods,UV-Vis and XPS Measurements

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.239-242.273 ◽

2011 ◽

Vol 239-242 ◽

pp. 273-278

Author(s):

Zhe Zhang ◽

Le Ruan ◽

Ming Zi Jia ◽

Ji Qiong Jiang ◽

Xing Shen Deng

Keyword(s):

Aqueous Solution ◽

Electrochemical Impedance Spectroscopy ◽

Photoelectron Spectroscopy ◽

Electrochemical Impedance ◽

Pt Nanoparticles ◽

The Self ◽

Iron Surface ◽

X Ray ◽

Vis Spectroscopy ◽

Self Assembled

In this article, Pt nanoparticles protected by 1-dodecanethiol (DDT) were self-assembled on iron surface forming mixed self-assembled films. Those nanoparticles were prepared in aqueous solution and transferred from water phase to toluene phase. The self-assembled films of nanoparticles protected by DDT were prepared on iron surface. The nanoparticles were characterized by UV-vis spectroscopy. Electrochemical impedance spectroscopy (EIS), polarization curves, X-ray photoelectron spectroscopy (XPS) were applied to characterize the self-assembled films on iron surface.

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Ruling Factors in Cinnamaldehyde Hydrogenation: Activity and Selectivity of Pt-Mo Catalysts

Nanomaterials ◽

10.3390/nano11020362 ◽

2021 ◽

Vol 11 (2) ◽

pp. 362

Author(s):

Marta Stucchi ◽

Maela Manzoli ◽

Filippo Bossola ◽

Alberto Villa ◽

Laura Prati

Keyword(s):

Photoelectron Spectroscopy ◽

Pt Nanoparticles ◽

Carbon Support ◽

Catalytic Performance ◽

Acid Sites ◽

Hydrogenation Catalysts ◽

Cinnamaldehyde Hydrogenation ◽

Transmission Electron ◽

Heat Treated ◽

Heating Treatment

To obtain selective hydrogenation catalysts with low noble metal content, two carbon-supported Mo-Pt bimetallic catalysts have been synthesized from two different molybdenum precursors, i.e., Na2MoO4 and (NH4)6Mo7O24. The results obtained by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) combined with the presence and strength of acid sites clarified the different catalytic behavior toward cinnamaldehyde hydrogenation. After impregnating the carbon support with Mo precursors, each sample was used either as is or treated at 400 °C in N2 flow, as support for Pt nanoparticles (NPs). The heating treatment before Pt deposition had a positive effect on the catalytic performance. Indeed, TEM analyses showed very homogeneously dispersed Pt NPs only when they were deposited on the heat-treated Mo/C supports, and XPS analyses revealed an increase in both the exposure and reduction of Pt, which was probably tuned by different MoO3/MoO2 ratios. Moreover, the different acid properties of the catalysts resulted in different selectivity.

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Ternary Composite of Molybdenum Disulfide-Graphene Oxide-Polyaniline for Supercapacitor

Journal of The Electrochemical Society ◽

10.1149/1945-7111/ac3f1e ◽

2021 ◽

Author(s):

Ke Qu ◽

Yuqi Bai ◽

Miao Deng

Keyword(s):

Graphene Oxide ◽

Molybdenum Disulfide ◽

Photoelectron Spectroscopy ◽

Electrochemical Impedance ◽

Light Emitting Diode ◽

Rate Capability ◽

Energy Storage And Conversion ◽

Carbon Paper ◽

Power Sources ◽

X Ray

Abstract The ever-increasing need for small and lightweight power sources for use in portable or wearable electronic devices has spurred the development of supercapacitors as a promising energy storage and conversion system. In this work, a simple, facile and easy-to-practice method has been developed to employ carbon paper (CP) as the support to coat molybdenum disulfide (MoS2) and graphene oxide (GO), followed by electrodeposition of polyaniline (PANI) to render CP/MoS2-GO-PANI. The preparation parameters, such as amounts of MoS2, GO and number of aniline electropolymerization cycles, have been optimized to render CP/MoS2-GO-PANI the best capacitive performance. The as-prepared optimal CP/MoS2-GO-PANI is characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The supercapacitive properties of CP/MoS2-GO-PANI as an electrode have been evaluated electrochemically via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy testing. CP/MoS2-GO-PANI delivers a specific capacitance of 255.1 F/g at 1.0 A/g and exhibits excellent rate capability under larger current densities. Moreover, a symmetrical supercapacitor is assembled and three are connected in series to power a light-emitting diode for ~15 minutes, demonstrating the promising application potential of CP/MoS2-GO-PANI-based supercapacitor.

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Preparation of Novel Ag–Si–TiO2 Composite and Research on Its Photocatalytic Degradation of Formaldehyde

Science of Advanced Materials ◽

10.1166/sam.2021.3864 ◽

2021 ◽

Vol 13 (3) ◽

pp. 371-380

Author(s):

Yongjun Wu ◽

Nina Xie ◽

Lu Yu

Keyword(s):

Photoelectron Spectroscopy ◽

Removal Rate ◽

Sol Gel ◽

Catalytic Performance ◽

Formaldehyde Concentration ◽

Order Kinetic ◽

Solution Ph ◽

Visible Absorption ◽

X Ray ◽

Co Doped

A novel Ag–Si–TiO2 composite was prepared via sol–gel method for removing residual formaldehyde in shiitake mushroom. The structure of Ag–Si–TiO2 composite was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. Ultraviolet-visible absorption spectroscopy (UV-Vis) and N2 adsorption-desorption tests showed that Ag and Si co-doped decreased the band gap, the Brunauer-Emmett-Teller (BET) specific surface area of the samples increased and the recombination probability of electron-hole pairs (e--h+) reduced. Effect on removal rate of formaldehyde with different Ag-Si co-doped content, formaldehyde concentration and solution pH were investigated, and the results showed that 6.0 wt%Ag-3.0 wt%Si-TiO2 samples had an optimum catalytic performance, and the degradation efficiency reached 96.6% after 40 W 365 nm UV lamp irradiation for 360 min. The kinetics of formaldehyde degradation by Ag–Si–TiO2 composite photocatalyst could be described by Langmuir-Hinshelwood first-order kinetic model.

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Influence of Sulfur-Containing Sodium Salt Poisoned V2O5–WO3/TiO2 Catalysts on SO2–SO3 Conversion and NO Removal

Catalysts ◽

10.3390/catal8110541 ◽

2018 ◽

Vol 8 (11) ◽

pp. 541 ◽

Cited By ~ 3

Author(s):

Haiping Xiao ◽

Chaozong Dou ◽

Hao Shi ◽

Jinlin Ge ◽

Li Cai

Keyword(s):

Photoelectron Spectroscopy ◽

No Reduction ◽

Catalytic Performance ◽

Acid Sites ◽

Impregnation Method ◽

So2 Oxidation ◽

Sodium Salts ◽

X Ray ◽

Temperature Programmed ◽

Physical Features

A series of poisoned catalysts with various forms and contents of sodium salts (Na2SO4 and Na2S2O7) were prepared using the wet impregnation method. The influence of sodium salts poisoned catalysts on SO2 oxidation and NO reduction was investigated. The chemical and physical features of the catalysts were characterized via NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). The results showed that sodium salts poisoned catalysts led to a decrease in the denitration efficiency. The 3.6% Na2SO4 poisoned catalyst was the most severely deactivated with denitration efficiency of only 50.97% at 350 °C. The introduction of SO42− and S2O72− created new Brønsted acid sites, which facilitated the adsorption of NH3 and NO reduction. The sodium salts poisoned catalysts significantly increased the conversion of SO2–SO3. 3.6%Na2S2O7 poisoned catalyst had the strongest effect on SO2 oxidation and the catalyst achieved a maximum SO2–SO3-conversion of 1.44% at 410 °C. Characterization results showed sodium salts poisoned catalysts consumed the active ingredient and lowered the V4+/V5+ ratio, which suppressed catalytic performance. However, they increased the content of chemically adsorbed oxygen and the strength of V5+=O bonds, which promoted SO2 oxidation.

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